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31 Days Before
Your CCNA Exam
Scott Bennett

Cisco Press

800 East 96th Street

Indianapolis, Indiana 46240 USA

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31 Days Before Your CCNA Exam

31 Days Before Your CCNA Exam
Scott Bennett
Copyright © 2007 Cisco Systems, Inc.
Published by:
Cisco Press
800 East 96th Street
Indianapolis, IN 46240 USA
All rights reserved. No part of this book may be reproduced or transmitted in any form or by any
means, electronic or mechanical, including photocopying, recording, or by any information storage
and retrieval system, without written permission from the publisher, except for the inclusion of
brief quotations in a review.
Printed in the United States of America 1 2 3 4 5 6 7 8 9 0
First Printing August 2006
Library of Congress Cataloging-in-Publication Number: 2005938126
ISBN: 1-58713-174-9

Warning and Disclaimer
This book is designed to provide information about the Cisco Networking Academy Program CCNA
curriculum. Every effort has been made to make this book as complete and as accurate as possible,
but no warranty or fitness is implied.
The information is provided on an “as is” basis. The authors, Cisco Press, and Cisco Systems, Inc.,
shall have neither liability nor responsibility to any person or entity with respect to any loss or damages
arising from the information contained in this book or from the use of the discs or programs that may
accompany it.
The opinions expressed in this book belong to the author and are not necessarily those of
Cisco Systems, Inc.

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Feedback Information
At Cisco Press, our goal is to create in-depth technical books of the highest quality and value. Each
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Trademark Acknowledgments
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About the Author
Scott Bennett earned his CCNA, CCAI, and CompTia A+ while working and teaching in the technology industry. After graduating from Gonzaga University, Scott went on to work with Qwest
eBits, providing network support and training to businesses throughout Idaho. His current position
as a Cisco Networking Academy instructor for the Capital Center High School Technology
Institute and Portland Community College provided the ideas and inspiration for this book.

About the Technical Reviewers
Mark R. Anderson, CCNA/CCNP, has been the lead Cisco Network Academy faculty at Mesa
Community College in Mesa, Arizona since 1999. His 25+ years in the IT industry has given him
invaluable experience in preparing and passing many technical certification exams, such as CCNA,
CCNP, MCSE, and MCNE. As a teacher, his passion has been to help students develop and expand
their professional growth in the IT industry. He earned a Bachelor of Education from Pacific Lutheran
University and a Master of Liberal Studies in Information Networking and Telecommunication
from Fort Hays State University. Mark lives in Gilbert, Arizona with Sandra, his wife of 35 years,
and nearby adult children, Clint, Jennifer, and Trisha.
Glenn Wright, CCNA, CCAI, is the co-director of the Cisco Academy Training Center (CATC) in
Ft. Worth, Texas. He has been involved in many aspects of the Cisco Networking Academy Program
since 1999. He serves the Academy Program as an instructor and supports academies in Texas,
Louisiana, Oklahoma, and Arkansas. Glenn has also worked with the Academy Quality Assurance
Team, reviewing and editing Academy curriculum and assessment.

qxd vi 7/28/06 8:52 AM Page vi 31 Days Before Your CCNA Exam Dedication To Grandpa Matt. Jim and Shari.00_1587131749_fm. Monnie. Angie. and to Pam and George. Johnny. Jimmy. my energetic and caring siblings. my loving and supportive parents. and Christi. . for creating my beloved beautiful wife.

Her enthusiasm. . and attention to detail while editing the text.qxd 7/28/06 8:52 AM Page vii vii Acknowledgments First. wealth of knowledge. Mark Anderson and Glenn Wright. Thank you to Dayna Isley for the innumerable improvements you contributed to the book and your positive encouragement. I greatly appreciate Allan Johnson’s willingness to use a draft of the text in his CCNA review class and provide advice and assistance. I want to thank Mary Beth Ray for her help in this process from start to finish. supervision. Thank you for this remarkable experience and opportunity. Pete Craemer and David Gilde for their encouragement as fellow educators at the Capital Center High School. for teaching me the real meaning of the words endurance and dedication. Lastly. and ability to turn an idea into a proposal amaze me.00_1587131749_fm. and Professor Steven Gillick for his enthusiasm in the classroom and generous distribution of red ink on my papers. thank you for pointing me in the right direction with the initial chapter and contributing the OSI model pneumonic device. professionalism. I also want to thank Matt Schoenfeldt for his continued and contagious eccentric passion about all things technical. Jeff Wirtzfeld for his support. Thank you to the entire Cisco Press team that worked behind the scenes to help create this book. thank you for your patience. Chris Cleveland. I want to thank Coach Dan Gehn. I also want to thank my friend Peter Buss for providing the perspective and empathy of a seasoned network administrator. and Gary Schlienkofer for his aid with our Local Cisco Networking Academy. and friendship at Qwest. I would like to thank Trevor Hardcastle and Weiping He for keeping me on my toes as a teacher and in hopes that they might include my name in all of their future books.

00_1587131749_fm. Subnet Masks.qxd viii 7/28/06 8:52 AM Page viii 31 Days Before Your CCNA Exam Contents at a Glance Part I : 31-24 Days Before the Exam—Technology 1 Day 31: Describe Network Communications Using Layered Models Day 30: Describe the Spanning Tree Process 3 11 Day 29: Compare and Contrast Key Characteristics of LAN Environments Day 28: Evaluate the Characteristics of Routing Protocols 15 19 Day 27: Evaluate the TCP/IP Communication Process and Its Associated Protocols 27 Day 26: Describe the Components of Network Devices Day 25: Evaluate Rules for Packet Control 35 39 Day 24: Evaluate Key Characteristics of WANs 43 Part II: 23–18 Days Before the Exam—Planning and Design Day 23: Design a Simple LAN Using Cisco Technology 47 49 Day 22: Design an IP Addressing Scheme to Meet Design Requirements 57 Day 21: Select an Appropriate Routing Protocol Based on User Requirements 63 Day 20: Design a Simple Internetwork Using Cisco Technology Day 19: Develop an Access List to Meet User Specifications 69 73 Day 18: Choose WAN Services to Meet Customer Requirements 77 Part III: 17–9 Days Before the Exam—Implementation and Operation 87 Day 17: Configure Routing Protocols Given User Requirements 89 Day 16: Configure IP Addresses. and Gateway Addresses on Routers and Hosts 99 Day 15: Configure a Router for Additional Administrative Functionality Day 14: Configure a Switch with VLANs and Interswitch Communication Day 13: Implement a LAN 121 105 113 .

00_1587131749_fm.qxd 7/28/06 8:52 AM Page ix ix Day 12: Customize a Switch Configuration to Meet Specified Requirements and Manage System Image and Device Configuration Files (Two Objectives) 125 Day 11: Perform an Initial Configuration on a Router and Perform an Initial Configuration on a Switch (Two Objectives) 133 Day 10: Implement an Access List 141 Day 9: Implement Simple WAN Protocols 145 Part IV: 8–1 Day(s) Before the Exam—Troubleshooting 153 Day 8: Utilize the OSI Model as a Guide for Systematic Troubleshooting Day 7: Perform LAN and VLAN Troubleshooting Day 6: Troubleshoot Routing Protocols 159 163 Day 5: Troubleshoot IP Addressing and Host Configuration 167 Day 4: Troubleshoot a Device as Part of a Working Network Day 3: Troubleshoot an Access List 175 Day 2: Perform Simple WAN Troubleshooting 177 Day 1: Key Points from Each Day for Relaxed Skimming Part V: Exam Day and Post-Exam Information Exam Day: Becoming a CCNA 205 Post-Exam Information: After the CCNA Index: 211 171 207 181 203 155 .

Module 1 16 CCNA 3. Module 6 15 CCNA 2. Module 2 15 CCNA 1. Module 4 16 CCNA 3.00_1587131749_fm. Module 6 19 CCNA 2. Module 2 3 CCNA 1. Module 5 17 Summary Your Notes 18 18 Day 28: Evaluate the Characteristics of Routing Protocols CCNA 2. Module 2 22 CCNA 3. Module 1 22 CCNA 3. Module 5 Summary Your Notes 6 9 9 10 Day 30: Describe the Spanning Tree Process CCNA 1. Module 11 CCNA 3. Module 3 23 Summary Your Notes 25 26 19 15 . Module 7 21 CCNA 3.qxd x 7/28/06 8:52 AM Page x 31 Days Before Your CCNA Exam Contents Part I : 31-24 Days Before the Exam—Technology 1 Day 31: Describe Network Communications Using Layered Models CCNA 1. Module 7 11 Summary Your Notes 3 11 12 13 Day 29: Compare and Contrast Key Characteristics of LAN Environments CCNA 1. Module 8 11 CCNA 3. Module 6 5 CCNA 1. Module 9 5 CCNA 1.

Module 1 35 CCNA 2. Module 3 45 CCNA 4. Module 2 36 Summary Your Notes 37 38 Day 25: Evaluate Rules for Packet Control CCNA 1. Module 10 CCNA 1. Module 1 43 CCNA 4. Module 2 28 CCNA 1. Module 11 Summary Your Notes 39 39 39 41 42 Day 24: Evaluate Key Characteristics of WANs CCNA 1. Module 2 43 CCNA 2. Module 5 45 Summary Your Notes 46 46 43 35 . Module 6 CCNA 2. Module 8 CCNA 2. Module 9 28 CCNA 1.qxd 7/28/06 8:52 AM Page xi xi Day 27: Evaluate the TCP/IP Communication Process and Its Associated Protocols 27 CCNA 1. Module 2 43 CCNA 4. Module 10 Summary Your Notes 31 32 32 32 33 34 Day 26: Describe the Components of Network Devices CCNA 2. Module 4 45 CCNA 4. Module 11 CCNA 2.00_1587131749_fm. Module 1 27 CCNA 1.

Module 1 61 Summary Your Notes 62 62 Day 21: Select an Appropriate Routing Protocol Based on User Requirements 63 CCNA 1. Module 1 65 CCNA 3. Module 2 65 CCNA 3. Module 8 70 69 57 . Module 2 69 CCNA 1. Module 5 50 CCNA 1.qxd xii 7/28/06 8:52 AM Page xii 31 Days Before Your CCNA Exam Part II: 23–18 Days Before the Exam—Planning and Design Day 23: Design a Simple LAN Using Cisco Technology CCNA 1. Module 9 57 CCNA 1. Module 10 63 CCNA 2. Module 1 57 CCNA 1.00_1587131749_fm. Module 6 64 CCNA 3. Module 8 51 CCNA 1. Module 1 60 CCNA 4. Module 1 Summary 55 56 Day 22: Design an IP Addressing Scheme to Meet Design Requirements CCNA 1. Module 2 49 CCNA 1. Module 10 54 CCNA 3. Module 10 58 CCNA 3. Module 5 54 Your Notes 49 53 CCNA 2. Module 3 66 Summary Your Notes 47 67 68 Day 20: Design a Simple Internetwork Using Cisco Technology CCNA 1. Module 9 52 CCNA 1.

Module 2 78 CCNA 4.00_1587131749_fm. Module 2 77 CCNA 1. Module 7 90 CCNA 3. Module 6 89 CCNA 2. Module 8 70 CCNA 4. Module 2 93 CCNA 3. Module 3 81 CCNA 4. Module 11 Summary Your Notes 73 73 74 75 Day 18: Choose WAN Services to Meet Customer Requirements CCNA 1. Module 4 83 CCNA 4. Module 1 89 CCNA 2. Module 2 71 Summary Your Notes 72 72 Day 19: Develop an Access List to Meet User Specifications CCNA 2. Module 1 70 CCNA 4. Module 1 92 CCNA 3. Module 3 96 Summary Your Notes 97 98 89 . Module 5 85 Summary Your Notes 77 86 86 Part III: 17–9 Days Before the Exam—Implementation and Operation 87 Day 17: Configure Routing Protocols Given User Requirements CCNA 2.qxd 7/28/06 8:52 AM Page xiii xiii CCNA 3. Module 1 78 CCNA 4. Module 5 77 CCNA 2.

Module 3 99 CCNA 3. Module 3 126 .00_1587131749_fm. Module 1 107 CCNA 4. and Gateway Addresses on Routers and Hosts 99 CCNA 1. Module 2 102 Summary Your Notes 103 104 Day 15: Configure a Router for Additional Administrative Functionality CCNA 2. Module 5 126 CCNA 2. Module 3 105 CCNA 4. Module 5 123 CCNA 1. Module 4 122 CCNA 1.qxd xiv 7/28/06 8:52 AM Page xiv 31 Days Before Your CCNA Exam Day 16: Configure IP Addresses. Module 4 125 CCNA 3. Module 9 99 CCNA 2. Module 7 124 Your Notes 113 118 Day 13: Implement a LAN Summary 105 121 124 124 Day 12: Customize a Switch Configuration to Meet Specified Requirements and Manage System Image and Device Configuration Files (Two Objectives) 125 CCNA 3. Module 1 99 CCNA 1. Module 8 113 CCNA 3. Module 9 115 Summary Your Notes 119 CCNA 1. Module 1 102 CCNA 3. Module 6 111 Summary Your Notes 112 112 Day 14: Configure a Switch with VLANs and Interswitch Communication CCNA 3. Subnet Masks. Module 2 121 CCNA 1.

Module 3 134 CCNA 3. Module 5 149 Summary Your Notes 145 151 152 Part IV: 8–1 Day(s) Before the Exam—Troubleshooting 153 Day 8: Utilize the OSI Model as a Guide for Systematic Troubleshooting CCNA 1. Module 2 155 CCNA 2. Module 2 133 CCNA 2. Module 5 Summary Your Notes 127 131 131 Day 11: Perform an Initial Configuration on a Router and Perform an Initial Configuration on a Switch (Two Objectives) 133 CCNA 2. Module 6 Summary Your Notes 157 158 157 157 155 . Module 1 145 CCNA 4. Module 11 Summary Your Notes 141 141 143 144 Day 9: Implement Simple WAN Protocols CCNA 2. Module 9 155 CCNA 2. Module 10 CCNA 4. Module 8 155 CCNA 2. Module 4 146 CCNA 4. Module 3 145 CCNA 4.00_1587131749_fm.qxd 7/28/06 8:52 AM Page xv xv CCNA 2. Module 6 135 Summary Your Notes 138 139 Day 10: Implement an Access List CCNA 2.

Module 2 164 CCNA 3. Module 9 163 CCNA 3. Module 4 171 CCNA 2. Module 3 165 Summary Your Notes 159 163 166 166 Day 5: Troubleshoot IP Addressing and Host Configuration CCNA 2. Module 11 Summary Your Notes 167 175 176 175 175 171 . Module 9 172 Summary Your Notes 172 173 Day 3: Troubleshoot an Access List CCNA 2.00_1587131749_fm. Module 8 161 Summary Your Notes 161 162 Day 6: Troubleshoot Routing Protocols CCNA 2. Module 9 168 Summary Your Notes 168 169 Day 4: Troubleshoot a Device as Part of a Working Network CCNA 1. Module 1 164 CCNA 3. Module 5 171 CCNA 2. Module 4 159 CCNA 2. Module 2 171 CCNA 2. Module 7 163 CCNA 2. Module 9 160 CCNA 3. Module 5 160 CCNA 2. Module 1 171 CCNA 2.qxd xvi 7/28/06 8:52 AM Page xvi 31 Days Before Your CCNA Exam Day 7: Perform LAN and VLAN Troubleshooting CCNA 2. Module 4 167 CCNA 2.

Module 4 177 CCNA 4.qxd 7/28/06 8:52 AM Page xvii xvii Day 2: Perform Simple WAN Troubleshooting CCNA 4. Module 3 177 CCNA 4.00_1587131749_fm. Module 5 178 Summary 177 178 Your Notes 179 Day 1: Key Points from Each Day for Relaxed Skimming Day 31 181 Day 30 182 Day 29 183 Day 28 183 Day 27 184 Day 26 185 Day 25 185 Day 24 186 Day 23 186 Day 22 187 Day 21 188 Day 20 188 Day 19 189 Day 18 189 Day 17 190 Day 16 191 Day 15 192 Day 14 193 Day 13 194 Day 12 194 Day 11 196 Day 10 197 Day 9 197 Day 8 199 181 .

00_1587131749_fm.qxd xviii 7/28/06 8:52 AM Page xviii 31 Days Before Your CCNA Exam Day 7 199 Day 6 200 Days 5 and 4 Day 3 201 Day 2 201 Summary Your Notes 200 201 202 Part V: Exam Day and Post-Exam Information Exam Day: Becoming a CCNA 205 What You Need for the Exam 205 What You Should Receive After Completion Summary 206 Post-Exam Information: After the CCNA Receiving Your Certificate Determining Career Options 207 207 Examining Certification Options If You Failed the Exam Summary Your Notes Index 211 208 209 208 208 207 205 203 .

. ■ Square brackets [ ] indicate optional elements. In actual configuration examples and output (not general command syntax). ■ Italics indicate arguments for which you supply actual values.00_1587131749_fm. ■ Braces within brackets [{ }] indicate a required choice within an optional element. boldface indicates commands that are manually input by the user (such as a show command). mutually exclusive elements.qxd 7/28/06 8:52 AM Page xix xix Icons Used in This Book Communication Server PC PC with Software Terminal File Server Sun Workstation Macintosh Access Server ISDN/Frame Relay Switch Cisco Works Workstation ATM Switch Modem Token Ring Token Ring Printer Laptop Web Server IBM Mainframe Front End Processor Cluster Controller Multilayer Switch FDDI Gateway Router Network Cloud Bridge Line: Ethernet Hub Line: Serial DSU/CSU DSU/CSU FDDI Catalyst Switch Line: Switched Serial Command Syntax Conventions The conventions used to present command syntax in this book are the same conventions used in the IOS Command Reference. The Command Reference describes these conventions as follows: ■ Boldface indicates commands and keywords that are entered literally as shown. ■ Braces { } indicate a required choice. ■ Vertical bars (|) separate alternative. ■ A command that does not fit on one line due to the constraints of the book’s width will continue on the next line with a two-space indent.

Use this book and its organized course of study to take the guesswork out of your comprehensive academy review for the CCNA.qxd xx 7/28/06 8:52 AM Page xx 31 Days Before Your CCNA Exam Introduction 31 Days Before Your CCNA Exam represents the end of your adventure through the Cisco Networking Academy CCNA courses 1–4. Who Should Read This Book? The primary audience for this book is anyone teaching or enrolled in the Cisco Networking Academy CCNA 4 WAN Technologies course or recent graduates of the Cisco Networking Academy CCNA curriculum who have not yet passed the CCNA exam. This book essentially offers a stepping-stone in what might otherwise feel like a big leap between the Cisco Networking Academy curriculum and the CCNA exam. exam #640-801).00_1587131749_fm. You owe it to yourself to complete your academy studies with a CCNA certification. Second Edition (ISBN 1587200791) by Jim Doherty and Eric Rivard. . This book can also provide instructors and students with a concise way to review all four courses at the end of a CCNA 4 class and add a little personality and a new angle to the Academy curriculum. This book also outlines the format of the CCNA exam and the registration requirements you must fulfill to take the CCNA exam. Goals and Methods The main goal of this book is to provide you with a clear map from the Cisco Networking Academy Program online curriculum to the CCNA exam. You can use this book to fit CCNA studies into an otherwise busy schedule with a daily timeline and clear references to other CCNA study materials. Time to take the CCNA 640-801 exam and make your knowledge official. Each day breaks down each exam topic into a manageable bite using short summaries from the online curriculum and a conversational tone to make your study time more enjoyable. You will read short summaries of sections from the Networking Academy online curriculum as they relate to each of the exam topics for the CCNA. Each day in the book uses the following formats to review the Networking Academy online curriculum: ■ Short summaries of key concepts and definitions from the curriculum with a reference to the Networking Academy online module section number ■ Tables and figures to help you recognize topics that you covered during your Networking Academy studies ■ No-frills Cisco IOS software command-line examples to jog your memory about the configurations and lab exercises that relate to each CCNA objective ■ References for further study and practice testing with the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study.

CCNA 2. the books starts by breaking up the exam topics by day. ■ Donate a set amount for every hour that you study to a children’s hospital. Your desire to get a CCNA and understand these concepts will shine through on test day. Look for daily reading quizzes and activities online. or CCNA 4). If you cannot explain and diagram an objective.00_1587131749_fm. The book counts down starting with Day 31 and continues through exam day to provide post-test information. and location of your CCNA exam. you will find a calendar and checklist that you can tear out and use during your exam preparation.ciscopress. Ask friends to sponsor you. The calendar provides a visual for the time you can dedicate to each CCNA exam objective.qxd 7/28/06 12:27 PM Page xxi xxi How This Book Is Organized After you read through the instructions provided later in this introduction for registering for the CCNA exam. planning and design. . Visit the book’s product page at www. The 31 days are broken into the four categories for the CCNA 640-801 exam: technology. you may find it helpful to buy a whiteboard. and tackle the suggested readings and practice exams for each day. The real test happens when your boss asks you to explain a networking concept or to defend your suggestion in a meeting. Use the checklist to map out your studies for the CCNA exam. Study Tips As you begin studying for the CCNA exam. Each day is titled with the CCNA exam objective. Each subheading provides the module and section from the Networking Academy course and then provides a brief description of topics related to that day’s exam objective. Use the calendar to enter each actual date beside the countdown day and the exact day. Teach whoever will listen. you need to inject yourself into this information. Get a dry erase marker and fill the room with that awful scent while you diagram and teach each of the concepts to yourself. The following activities could also help you to prepare: ■ Podcast audio discussions about CCNA topics. like those movie montages where the lead character is preparing for something very important. time. ■ Blog what you are learning. and each heading identifies the Networking Academy course (CCNA 1. ■ Get a copy of CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study. CCNA 3. More important than anything. ■ Capture video lessons of yourself and watch them. then you do not know it. implementation and operation.com/title/1587131749 to access the content. Second Edition (ISBN 1587200791). and troubleshooting. Teach out loud. The checklist highlights important tasks and deadlines leading up to your exam. At the end of the book. You can also put a red X on each day you complete. exam #640-801).

■ Implementation and operation—This category is where you prove that you can actually connect and configure a network. ■ Planning and design—This category asks you to organize the concepts of networking into real-world examples. Although Cisco outlines general exam topics. compare.qxd xxii 7/28/06 8:52 AM Page xxii 31 Days Before Your CCNA Exam Getting to Know the CCNA Exam The CCNA 640-801 tests your ability to describe. including layered models as well as network process descriptions. format. . but also knowing the testing process. In this book. connect. configure. and the occasional malfunctioning keyboard during IP address configuration.00_1587131749_fm. and troubleshoot networks. Each category includes general exam topics. but you need this category to fix networks affected by natural disasters. You can navigate to CCNA information through the Learning and Events link. hardware issues. and environment will build your confidence and reduce the chance of any unpleasant surprises on exam day. your networks are always perfect. The exam topics provided by Cisco and included in this book are a general framework for exam preparation. Just knowing the information will help you on the exam. it is possible that not all topics will appear on the CCNA exam and that topics that are not specifically listed may appear on the exam. Exam Topics The topics of the CCNA 640-801 exam focus around the following four key categories: ■ Technology—The topics in this category relate to the theory and concepts behind networks. Be sure to check Cisco. ■ Troubleshooting—As a Cisco Networking Academy student.com and look at the latest exam topics. each day represents a CCNA exam topic and each day maps the information you have learned in the Cisco Networking Academy Curriculum to a CCNA exam topic.

Testlet You see an upper pane and lower pane in the main window for this type of task. Cisco. Step 5. The following steps allow you to access this tutorial: Step 1. Multiple-choice multiple answer You choose more than one answer.cisco. Table I-1 outlines each type of question that you might encounter on the exam. you are allowed 90 minutes to answer 55–65 questions. On the right side. The question itself will tell you how many answers you must select. and the lower pane contains multiple-choice questions with single and multiple answers. Step 2. Click the Certification Exam Information link. Click the Certification Exam Tutorial link. Remember that not all commands are supported in these simulations and that you can view the topology of the network in some simulations. Simlet A top window pane contains questions. you can scroll through the scenario and select questions. Sometimes there will be more than one text box. Click the Learning and Events link. and a bottom window pane contains a router simulation that you can use to answer the questions. Visit http://www. Simulations This task is similar to the e-Labs that cover configurations. . The upper pane contains a scenario.00_1587131749_fm. Step 4. Click the Career Certifications and Paths link. You see the actual problem at the top and the directions on the left.com. Step 3.com has an exam tutorial that simulates each of these types of questions. Table I-1 CCNA Question Types Question Type Description Multiple-choice single answer You choose one and only one option for an answer.qxd 7/28/06 8:52 AM Page xxiii xxiii Exam Format For the CCNA exam. Fill-in-the-blank You click a text box and then type the answer. Drag-and-drop You drag and release objects to visually arrange the answer on the page. These questions are similar to the drag-and-drop Interactive Media Activities in the Academy online curriculum. As you work through the exam tutorial. identify the question types that will take you longer to complete so that you can manage your time on exam day.

you should plan to pass the CCNA voucher exam and take advantage of the practice and skills exams available through the Cisco Academy web site. The default duration of the exam is 75 minutes. CCNA 640-801 Certification Practice Exams 1 and 2 The CCNA Certification Practice Exams 1 and 2 have between 55 and 60 questions.qxd xxiv 7/28/06 8:52 AM Page xxiv 31 Days Before Your CCNA Exam Your Path to the CCNA As a Cisco Networking Academy student. multiple-answer questions. You can take these exams up to ten times each. CCNA 640-801 Voucher Exam Your instructor can activate and proctor this exam for you through the Cisco Academy web site during the CCNA 4 course.00_1587131749_fm. You must be enrolled in a CCNA 4 class and request that your instructor enable these practice exams in the Cisco Academy online assessment system. Your voucher will be redeemable for a discount on the CCNA exam at a Prometric or Pearson VUE testing center. If you pass the voucher exam and have successfully completed all final exams for The Cisco Networking Academy CCNA 1 through CCNA 4 with a 70 percent or better in the first attempt. It is important to schedule the following three exams with your Academy instructor in order to be best prepared for the CCNA: ■ CCNA 640-801 Voucher Exam ■ CCNA 640-801 Certification Practice Exam 1 ■ CCNA 640-801 Certification Practice Exam 2 After completing these exams. Before you complete CCNA 4. . you will be able to request a voucher from your Cisco Academy home page. You have three attempts (each a different form of the exam) to complete with a score of “voucher eligible. The discount percentage varies by region and testing center. single-answer and multiple-choice.” The specific percentage that indicates “voucher eligible” is different for each form. and you are allowed 120 minutes on each exam by default. you can register to take the CCNA exam. and the exam includes multiple-choice. you have a unique opportunity to integrate your final days of the study with preparation for the CCNA exam.

you need to gather the information outlined in Table I-2 to register for the CCNA 640-801 exam.com There is no better motivation for study than an actual test date. Table I-3 Test Delivery Partners Testing Partner Phone Number Website Pearson VUE 1-800-829-6387 option 1 then option 4 http://www. You can contact the testing partners in Table I-3 to register for an exam. Sign up as soon as you have your voucher. it is important to ensure that your profile is updated with your Academy information for the Academy voucher before you register.com/cisco Thomson Prometric 1-800-829-6387 option 1 then option 4 http://securereg3. .prometric.00_1587131749_fm.qxd 7/28/06 8:52 AM Page xxv xxv Registering for the CCNA Exam Once you have taken these exams and redeemed your voucher. If you had an account with a testing partner before you began with the Academy.vue. The process and available test times will vary based on how and with whom you decide to register. Table I-2 Personal Information for CCNA 640-801 Exam Registration Item Notes Legal name Social Security or passport number Cisco certification ID or test ID Cisco Academy username Required for your voucher Cisco Academy ID number Required for your voucher Company name Valid e-mail address Voucher number Required for your voucher Method of payment Typically a credit card You can register for an exam up to six weeks in advance or as late as the day before the exam.

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01_1587131749_Pt1.qxd 7/28/06 8:52 AM Page 1 Part I 31-24 Days Before the Exam— Technology Day 31: Describe Network Communications Using Layered Models Day 30: Describe the Spanning Tree Process Day 29: Compare and Contrast Key Characteristics of LAN Environments Day 28: Evaluate the Characteristics of Routing Protocols Day 27: Evaluate the TCP/IP Communication Process and Its Associated Protocols Day 26: Describe the Components of Network Devices Day 25: Evaluate Rules for Packet Control Day 24: Evaluate Key Characteristics of WANs .

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Module 2 2.3. Look in the curriculum for related charts and graphics. so the OSI model was released in 1984. Keep in mind that peer layers communicate with each other.5—Here is Yet Another OSI Model Chart (YAOMC).4 and 2.1—As you track the flow of information across a network.2—When two nodes communicate.3. you will notice specific points where data changes on its route to a destination.02_1587131749_DAY31. The networking models from CCNA 1 provide a framework for the concepts and configurations covered throughout the Cisco Networking Academy Program curriculum.3. 9. 2. The layers of the OSI and TCP/IP models help to explain why these changes occur and the process that helps the data find its way from one node to the next.qxd 7/28/06 8:52 AM Page 3 Day 31 Describe Network Communications Using Layered Models If the CCNA had a skeleton. 6. networking models would be it. Today you cover the Open System Interconnection (OSI) and TCP/IP layered models described in Modules 2. A solid understanding of these models prevents your network knowledge from resembling spineless. Table 31-1 describes each layer of the OSI model. Many other online resources. Note that the protocol data unit (PDU) for each layer is in italics. companies developed proprietary network technologies that naturally caused compatibility issues. A mnemonic such as Please Do Not Throw Sausage Pizzas Away might help you to remember each of the seven layers quickly for the exam.wikipedia. You might even have something to add to the Wikipedia explanations after your studies. 2. and 11 from CCNA 1 and the Cisco three-layer hierarchical model described in Module 5 from CCNA 3. they follow a protocol or an agreed upon set of rules to ensure the successful transmission of data.com). It wouldn’t be a CCNA book without one. Do not stop with the quick summaries provided today. shapeless jelly. .3—Initially. such as Wikipedia (www.3.3. The benefits of using the OSI model to describe networks and networking devices are as follows: ■ Reduces complexity ■ Standardizes interfaces ■ Facilitates modular engineering ■ Ensures interpolable technology ■ Accelerates evolution of networks ■ Simplifies teaching and learning 2. CCNA 1. also have excellent explanations.

and other programs that allow the user to enter data. In the top three layers. Data is represented in a standard syntax and format such as ASCII. Router 2 Data link Frames traverse the LAN with a MAC address as the identifier.3. N/A 3 Network Packets are routed over the network and receive a path based on their IP address.3. FTP. N/A 4 Transport Segments are transported with reliability. . switch 1 Physical Bits physically pulse or wave their way over the network media representing 1s and 0s. and tear down for sessions between programs exchanging data.qxd 4 7/28/06 8:52 AM Page 4 31 Days Before Your CCNA Exam Table 31-1 The Open System Interconnection Seven-Layer Model Layer Layer Name Number Function Devices 7 Application E-mail. Finally. The U. When data enters the transport layer. Bridge. it is packaged into segments. The data link layer packages the packet into a frame and adds a source and destination MAC address. error detection. Table 31-2 matches the layers of the TCP/IP model with the OSI model. Table 31-2 The TCP/IP Model Versus the OSI Model TCP/IP Model OSI Model 4 Application 7 Application 6 Presentation 5 Session 3 Transport 4 Transport 2 Internet 3 Network 1 Network Access 2 Data link 1 Physical 2. wireless 2. optical. repeater. and flow control.7—The PDUs identified in the OSI model are encapsulated as they travel through the layers and from host to destination. management. the frame becomes a series of bits for transmission over the physical media. N/A 5 Session Set up. the data remains data. The network layer then packages the segments into packets and adds a source and destination IP address. copper.02_1587131749_DAY31.6—The TCP/IP model achieves the same main goals as the OSI model. Hub.S. Department of Defense developed the model to define a network that could withstand nuclear war. N/A 6 Presentation Encryption and compression can occur.

FDDI and Token Ring are deterministic in that they provide a way to take turns accessing the media. 802. Cyclic redundancy check (CRC) is a common way to calculate the number and check for errors in the frame. Unless otherwise noted.1.1—Three Layer 2 technologies that control how the physical media is accessed are Ethernet.1. The same layers in the different models have different functions.02_1587131749_DAY31. ■ The lower sublayer is the MAC sublayer.3—The data link layer of the OSI reference model consists of two sublayers: ■ The upper sublayer is the Logical Link Control (LLC) sublayer. The MAC sublayer controls access to the physical media.1. destination.qxd 7/28/06 8:52 AM Page 5 Day 31 5 CCNA 1. these technologies can be divided into two groups: deterministic and nondeterministic. Token Ring. a collision will occur and both nodes will wait a random amount of time before trying again. end.1—Do not confuse the OSI and TCP/IP models despite the fact that some of the layers have the same name. Module 6 6. most CCNA questions will reference the OSI model. 6. Pay close attention to the layer name and model name in any layered model question. 9. Ethernet is nondeterministic and uses carrier sense multiple access collision detect (CSMA/CD) as the protocol for accessing the media. upper layers refers to Layers 3–7 in the OSI model and Layers 3 and 4 in the TCP/IP model.2—The application layer of the TCP/IP model includes programs and protocols that prepare the data to be encapsulated in the lower layers.1.2. Examples of these programs are as follows: ■ FTP ■ TFTP . The fields in a generic frame are as follows: ■ Start of Frame—This field identifies the beginning of a frame. As part of the MAC sublayer. ■ Address—This field contains the source and destination MAC address. and successful transfer of a frame. if it is a type field. If two nodes transmit at the same time. it defines the length of the frame. (In this case. Without frames. CCNA 1. This means that a node will first check to see if there is already a transmission and begin sending if the line is available.) ■ Frame Check Sequence—This field provides a number that represents the data in the frame and a way to check the frame and get the same number. it identifies the Layer 3 protocol for the frame. The LLC sublayer communicates with the upper layers of the OSI model.3 Ethernet operates in the physical layer of the OSI model and in the MAC sublayer of the data link layer. These fields allow the receiving host to identify the beginning. 6.5—Layer 2 frames are made up of fields. ■ Length/Type—If this is a length field. Module 9 9. the transmission would be just a big stream of ones and zeros. and FDDI. ■ Data—Where the data resides that is processed by the upper layers.

1. The OSI model appears more in academic and theoretical situations. Examples of these protocols are as follows: ■ Ethernet ■ Fast Ethernet ■ Point-to-Point Protocol (PPP) ■ FDDI ■ ATM ■ Frame Relay 9. segment sequence numbers.4—The TCP/IP Internet layer finds the path for packets over the network. and is classified as a connection-oriented protocol. The TCP/IP internet layer also uses Address Resolution Protocol (ARP) to find a MAC address and Reverse Address Resolution Protocol (RARP) to find an IP address.1. The application initiating the connection and the operating system communicate .qxd 6 7/28/06 8:52 AM Page 6 31 Days Before Your CCNA Exam ■ Simple Mail Transfer Protocol (SMTP) ■ Simple Network Management Protocol (SNMP) ■ Telnet ■ Domain Name System (DNS) 9.02_1587131749_DAY31.1. The trans- port layer achieves these goals through sliding windows.1—When you think about the transport layer.3—In order to start passing segments at the transport layer. This layer includes the connectionless protocol IP and Internet Control Message Protocol (ICMP). two hosts must set up and maintain a session. UDP is a connectionless protocol that sends the data without verifying a successful transfer. CCNA 1.3—TCP and UDP operate as protocols of the TCP/IP transport layer. This flow control allows the receiving host to process the information in time to receive new segments from the sending host. provides flow control. also called the host-to-network layer. 9. however.1.1. whereas the TCP/IP model is the basis for development of the Internet. Know both models. they agree on a reasonable flow of information. fiber. 11.1. TCP.6—Pay close attention to the fact that the application layer of the TCP/IP model includes the application.2—When two hosts establish a logical TCP connection at the transport layer.5—The TCP/IP network access layer. 11. Module 11 11. presentation. 9. provides the proto- cols to access the physical media and the standards for the media (wires. consider flow control and reliability. Both TCP and UDP segment data from the TCP/IP application layer and send the segments to the destination host. and radio frequency). ensures reliable transfer with acknowledgments and sequencing. and session layers of the OSI model and that the TCP/IP network access layer includes the data link and physical layers of the OSI model.1. and acknowledgments.

6—How does the sending host know to retransmit a segment? As mentioned previously.1. and 6. the sending host would have to retransmit segment 3. the sending host’s need to retransmit relies on the numbers sent with acknowledgments. A host initially sends a segment with a window size of 1. retransmission occurs in the negotiation of a window size. 5. 2. 11. reliable transfer that TCP provides.1.6 in the CCNA 1 curriculum. The receiving host could respond with an acknowledgment and identify that it would like a window size of 2. and Telnet use the transport layer TCP protocol. and 3 over to the receiving host and receives an ACK 4. If at some point during this transfer the receiving host does not acknowledge the transfer. This three-way handshake defines the sequencing for TCP communication. Remember that both hosts must send an initial sequence number and receive an acknowledgment for communication to proceed. 11. Send a SYN.7—FTP.02_1587131749_DAY31. the sending host tries again with a smaller window size. Figure 31-1 TCP Sliding Window Sender Receiver Send 1 Send 2 Send 3 Receive 1 Receive 2 Receive 3 Send ACK 4 Receive ACK 4 Send 4 Send 5 Send 6 Receive 4 Receive 5 Receive 6 Send ACK 7 Receive ACK 7 Window Size = 3 11.1. If a sending host fires segments 1. All of these protocols benefit from the connection-oriented.4—Applications that use the connection-oriented protocol TCP at the transport layer must first set up a session. SMTP. and you are connected using the TCP protocol. receive an ACK. These sliding windows control flow between the two hosts. The fields of a TCP segment are as follows: ■ Source port ■ Destination port .1.1. send back an ACK +1. To further explain the process. Try illustrating this process. If the receiving host were to return only an ACK 3. 11.) If you need help. visit module 11.qxd 7/28/06 8:52 AM Page 7 Day 31 7 with the receiving host’s application and operating system to set up and synchronize a session. TCP avoids congestion at the transport layer by allowing the receiving host to send ready and not ready indicators to the sending host. HTTP. it knows to send segments 4. (You can use the “Your Notes” section that appears after today’s summary. as shown in Figure 31-1. The sending host shoots back two segments and the receiving host acknowledges and asks for a window size of 3.5—TCP can play with these ACKs to define how much can be sent using sliding windows.

This port is not one of the well-known port numbers assigned by the Internet Assigned Numbers Authority (IANA) because it provides standard port numbers below 1024 for protocols such as FTP (port 21 TCP) and HTTP (port 80 TCP).02_1587131749_DAY31. sequence. Notice in the following UDP fields that there are no acknowledgement. DHCP.1. The destination host must connect on a standard port number while the source host dynamically assigns a number above 1023 for the source port number. you are likely hosting a video game.1. and DNS use the connectionless transport layer protocol UDP. and window fields: ■ Source port ■ Destination port ■ Length ■ Checksum ■ Data 11.9—If someone connects to your desktop on port 27015. Table 31-3 Transport Layer Ports Application Layer Protocol Transport Layer Port/Protocol http Port 80 TCP FTP Port 21 TCP Telnet Port 23 TCP SMTP Port 25 TCP DNS Port 53 UDP and TCP TFTP Port 69 UDP SNMP Port 161 UDP RIP Port 520 UDP . Memorize the common registered TCP and UDP port numbers for the protocols included in Table 31-3.qxd 8 7/28/06 8:52 AM Page 8 31 Days Before Your CCNA Exam ■ Sequence number ■ Acknowledgment number ■ Header length (HLEN) ■ Reserved ■ Code bits ■ Window ■ Checksum ■ Urgent pointer ■ Option ■ Data 11. UDP streams its segments at the receiving host and leaves the error checking to the upper-layer protocols.8—TFTP. SNMP.

In the “Your Notes” section that follows.1–11.02_1587131749_DAY31. The access layer connects users and remote sites to the network. This model consists of the core. FTP and TFTP FTP allows connection-oriented TCP-based file transfer between a client and a server. CCNA 3.2. The distribution layer divides the core layer from the access layer and provides policy-based connectivity. which provide an outline for the types of devices and connectivity necessary in a large network. Table 31-4 Application Layer Protocols Protocol Description DNS The DNS represents an IP address with a domain name.2.1—Networking engineers use a three-layer hierarchical model to describe and design networks. now is a good time to review pages 13–34. Each domain name has an extension such as . it would be wise to diagram each of these layers and their characteristics from memory. SNMP SNMP allows an administrator to observe activity and troubleshoot problems on a network. The threelayer hierarchical model has three layers. and access layers.com that helps to identify the purpose of the site. HTTP HTTP uses TCP and allows a user to navigate web sites on the Internet using a browser. The core layer serves as the backbone reserved for high-speed transmission. Module 5 5. and then to bits. SMTP SMTP uses TCP at OSI Layer 4 to send e-mail. distribution. If you have the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study. to frames. Telnet Telnet provides a command-line interface to a remote host. Summary The OSI model and its seven layers cover each aspect of networking as data changes to segments.qxd 7/28/06 8:52 AM Page 9 Day 31 9 11. .7—Each of the application layer protocols in Table 31-4 provides a key function for Internet use. Second Edition (ISBN: 1587200791). TFTP uses the connectionless UDP protocol to transfer files without the feature set of FTP. published by Cisco Press. exam #640-801). Only four layers comprise the TCP/IP model. It is possible to transfer Cisco IOS images using TFTP. to packets.2. A network management system can collect information provided by network devices.

qxd 10 7/28/06 8:52 AM 31 Days Before Your CCNA Exam Your Notes Page 10 .02_1587131749_DAY31.

A switch can forward a frame forever. but if a switch does not know the destination MAC address of a frame. Each nonroot bridge will have one root port. A BID contains the bridge priority number (32768 by default) and the switch MAC address. CCNA 1. switches block nondesignated ports.4—To determine the root bridge. and the network is converged. Module 8 from CCNA 1 and Module 7 from CCNA 3 describe STP and its operation.2.3—BPDUs spread across the network. a network administrator needs to set the bridge priority number. The designated port is the only port to forward STP traffic onto the segment under normal converged conditions. Each switch assumes that it is the root bridge and initially sends out its BID as the root ID. As mentioned previously in the section “CCNA 1. Module 8” under 8. 7. the logical tree is in place. At Layer 2. The logical tree starts at the root bridge.1. 7. but if you start to add backup connections to a switched network it is imperative to also run the Spanning Tree Protocol (STP). The switch with the lowest BID becomes the root bridge. CCNA 3.03_1587131749_DAY30.6—Redundantly connected switches provide a valuable backup connection. switches that are closest to the LAN become designated switches to forward traffic from that LAN. All switch ports can transition from blocking to learning to listening and then to forwarding during this process. Switches running STP send bridge protocol data units (BPDUs) out each port to identify and block redundant paths. The network should now have only one root bridge per network and one designated port per segment.2. switches also send a bridge ID (BID) with BPDUs. Designated ports and root ports can forward data traffic.2—STP is defined by the IEEE 802. a switch has no way of recognizing and discarding a frame that it has already received. switches start out by sending BPDUs across the network that allow each switch to identify the root bridge and build a logical tree by turning off nondesignated ports and maintaining a single link with designated ports. but it is important that these backup connections do not cause loops.2. To ensure that a certain switch becomes the root bridge. To avoid loops.1d standard and identifies the shortest paths in a switched network to build a loop-free topology. If there are multiple LAN segments. 7. Module 7 7.2. it broadcasts (floods) that frame out all ports except the receiving port. A switch that does not have the lowest BID will replace its ID as the root bridge with the lowest BID that it receives from other switches.1. .1—Switches filter by MAC address. Module 8 8.qxd 7/28/06 8:52 AM Page 11 Day 30 Describe the Spanning Tree Process Switches can filter frames by MAC address and can speed up a network. redundantly connected switches must create a logical tree over which to send frames using the spanning tree algorithm. STP uses the spanning tree algorithm to turn off redundant connections until they are needed.6.

published by Cisco Press.2. spanning tree has successfully set up a logical tree and the network has converged. 7. Point-to-point and edge-type links in RSTP can cycle directly from blocking (renamed discarding) to forwarding. forwards data. In your notes. but IEEE 802. CCNA 3.5—Table 30-1 defines the states that a switch port can cycle through when connected to a network. Module 7. 7. Remember that a switch port can also be administratively disabled. RSTP can converge in 15 seconds. Second Edition (ISBN: 1587200791).03_1587131749_DAY30. If you have the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study. The small amount of material covered today also gives you an opportunity to take your first timed Networking Academy online CCNA practice exam. in the online curriculum has some great examples if you need help. A change in the physical topology of a network causes spanning tree recalculation to occur in order to once again achieve convergence.2.2. Table 30-1 Spanning-Tree Port States Port State Description Blocking The port looks only at BPDUs.qxd 12 7/28/06 8:52 AM Page 12 31 Days Before Your CCNA Exam 7. exam #640-801). Dive in and make your best attempt with the understanding that it is your first attempt. while STP takes up to 50 seconds. Forwarding The port learns MAC addresses. Listening The port checks for multiple paths to the root bridge and blocks all ports except the port with the lowest cost path to the root bridge. Learning The port learns MAC addresses but does not forward data.6—If all switch ports on a network are only in blocking or forwarding mode.1d STP prevents switching loops. . one that explains identification of the root bridge (showing BIDs).1w Rapid Spanning Tree Protocol (RSTP) does it faster. you might thumb through pages 301–329. and one that depicts a converged network with each port labeled. Summary To achieve convergence and a logical tree with no loops. try drawing three diagrams—one that explains how a switching loop could occur. and processes BPDUs.7—IEEE 802. switches use STP or RSTP.

03_1587131749_DAY30.qxd 7/28/06 8:52 AM Page 13 Day 30 Your Notes 13 .

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These terms include the following: ■ Bus—All devices connected to one single arterial cable ■ Ring—Each host connected to two other hosts forming a ring ■ Star—All hosts connected to a hub or switch ■ Extended Star—Hosts connected to a hub or switch that is in turn connected to a hub or switch ■ Hierarchical—A pyramid of extended star networks all connecting to a main proxy that handles traffic at the top of the pyramid ■ Mesh—All hosts directly connected to all other hosts Logical topologies determine how the hosts communicate across the medium. or FDDI in LAN technologies. Module 2 2. networking media.qxd 7/28/06 8:52 AM Page 15 Day 29 Compare and Contrast Key Characteristics of LAN Environments From casinos in Las Vegas to basements filled with mouse-clicking gamers. Token Ring. how data is transferred. 2. These rules are defined as protocols. The two most common logical topologies are token-passing or broadcast. called the Organizational Unique Identifier (OUI). network interface cards.1. and network devices make up the main parts of a LAN. Module 6 6. How you characterize and define the physical and logical topologies of these LANs is the key to configuring and troubleshooting them.5—Networks need a set of rules to determine how they communicate. A MAC address can also be called a burned-in address (BIA). Each frame that a . Modules 2 and 6 from CCNA 1.1.4—The terms to describe the physical topology of a network help you to explain how all the devices are connected. Network protocols control the type of connection. CCNA 1. The IEEE assigned those first six hex numbers to Intel (the company that made the network card).6—Computers. You most often use Ethernet.1. CCNA 1. 2. peripheral devices. Intel gets to assign the last six hex numbers. and how to handle errors.04_1587131749_DAY29.4—00-B0-D0-06-00-A3 is the 48-bit MAC address of the host that I am using to write this section. and Modules 4 and 5 from CCNA 3 provide the information needed to properly characterize a LAN environment. you encounter LANs.1. Module 1 from CCNA 2.

04_1587131749_DAY29. can filter each port based on the Layer 2 MAC address and provide a separate collision domain for each connected device.7—The fields of an Ethernet frame are as follows: ■ An Ethernet frame begins with a preamble made up of alternating 1s and 0s. or multiport bridge. ■ The Data field is followed by the Frame Check Sequence (FCS) field. .1—Ethernet 802. This switch. it represents the type of protocol. The original Digital Intel and Xerox (DIX) version of Ethernet (Ethernet II) not only combined the preamble and start of frame delimiter.6—Ethernet frames did not always have a length field. If you build a LAN today.3 LANs started as simple networks connected with a hub or concentrator and evolved into sophisticated topologies operating on many layers of the OSI model. The router acts as the gateway for LAN devices and operates at Layer 3 of the OSI model. ■ The Destination and Source Address fields are next. All hosts on that LAN drop the frame unless the destination MAC address in the frame matches the MAC address of the host. This segments the LAN from other LANs and reduces overall traffic. Bridges were able to look at the MAC address and decide whether or not to forward a frame. TCP/IP today uses a length/type field to identify upper-layer protocols in IEEE 802. you will likely connect devices with a switch. Module 4 4. All signals traveled over the hub network to all devices. so a Layer 3 router functions as the gateway that filters all LAN traffic and only forwards information destined for other connected LANs. CCNA 3. 0x0800 hex is IP.3 Ethernet. If the Length/Type field is less than 0x600 hex. Hubs. but also listed the length/type field as just type. Networks could now be divided into two separate collision domains. ■ The Length/Type field follows. A router will only forward data outside of a LAN if it is destined for another network. Switches and bridges do not filter broadcasts.1. or multiport repeaters. If the Length/Type field is greater than or equal to 0x600 hex. ■ The Start of Frame delimiter identifies the end of the preamble with the byte 10101011. CCNA 2.1. became common in networks as a way to retime and amplify signals to devices now connected in a star topology. 6. Module 1 1. it represents the length of the data in the next field. Routers communicate with each other to build routing tables allowing them to select the best path for a data packet between LANs. Initially. for example. so the potential for a collision existed on the entire network.3—A LAN connects to other LANs and the Internet through a router. LANs connected using thick Ethernet and thin Ethernet using a bus topology. Layer 2 bridges were introduced and did not just retime and regenerate the signals like a hub.1. 6.1.qxd 16 7/28/06 8:52 AM Page 16 31 Days Before Your CCNA Exam host sends over the LAN includes a destination MAC address. ■ The Data field contains information to be handled at the next layer.

1. This type of connection allows each of the two hosts to both transmit and receive at the same time. switches can also operate in adap- tive cut-through mode.8—Remember that devices can send out Layer 2 broadcasts to contact all hosts with a desti- nation MAC address of FF-FF-FF-FF-FF-FF. Routers filter broadcasts and forward only packets that are destined for other networks to other ports.1. Switches do not divide broadcast domains. and switches improve network functionality because they protect hosts from unnecessary traffic. The more devices you connect to a hub on a half-duplex network.” . the device that notices the collision sends a jam signal.1 occur when two devices attempt to transmit or receive at the same time. Switches divide collision domains and only pass frames over the wire to hosts with the proper destination MAC address.4—Shared Ethernet networks that operate in half-duplex can allow only one host to transmit or receive at a time. It would be difficult to sell IP phones to a school connected with all hubs. 4.2—In addition to cut-through or store-and-forward modes. 4. “Design a Simple LAN Using Cisco Technology.6—Network latency slows connectivity and is an especially sour term for network gamers. consider how many hosts populate each collision and broadcast domain. 4. 4. Use switches to segment collision domains and routers to filter broadcasts.1. Without routers to filter these broadcasts. Excessive collisions can congest a network. the switch operates in cut-through until there are a certain number of errors that cause it to switch to store-and-forward. the Internet would be pretty darn slow. Module 5 5. bridges.5—Routers. 4. On an Ethernet network.2. Store-and-forward mode results in the switch receiving the entire frame before forwarding the information. this is defined as carrier sense multiple access collision detect (CSMA/CD).1. Switches can operate in cut-through or store-and-forward modes.3. allowing for a 20 Mbps connection on a 10 Mbps network.3.04_1587131749_DAY29. When this happens. In cut-through mode. These frames are still broadcast to all hosts by switches. This mode is a combination of cut-though and store-and-forward.7—The host-to-host virtual circuit that a switch creates can be referred to as microsegmenta- tion. You will revisit all of Module 5 from CCNA 3 on Day 23.3. CCNA 3.1. for example. Initially. 4.10—The latency caused by a switch relates directly to how it processes a frame. The collisions mentioned in this section under 4. This full-duplex communication uses all the bandwidth in both directions.1.2—When you design a LAN. the higher the potential for a collision. Layer 3 devices can increase latency because they take more time than a Layer 2 device to process network data. and both devices wait a random amount of time (based on a backoff algorithm) before attempting to use the network again. switches can use MAC addresses to create direct virtual connections between two hosts on a network. 4. each port on a switch is its own collision domain.9—As mentioned previously in this section under 4. a switch either sends the frame as soon as it knows the destination MAC address (fast-forward) or reads the first 64 bytes and then sends the frame (fragment-free). The time it takes a network interface card (NIC) to receive or place a signal on a wire and the time it takes that signal to travel over the network contributes to latency.1. Because switches can microsegment networks into virtual circuits based on the MAC address filtering.qxd 7/28/06 8:52 AM Page 17 Day 29 17 4.3.

How you use network devices and physical design to organize a LAN will decide the speed and efficiency of your network. if you have one sitting near you.04_1587131749_DAY29. exam #640-801). In your notes you might sketch each of the physical and logical topologies that this chapter mentions.qxd 18 7/28/06 8:52 AM Page 18 31 Days Before Your CCNA Exam Summary LANs provide the local connectivity that supports business as well as important entertainment and therapeutic applications. Your Notes . Second Edition (ISBN: 1587200791). It would also help to quiz yourself on pages 36–60 of the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study.

6.qxd 7/28/06 8:53 AM Page 19 Day 28 Evaluate the Characteristics of Routing Protocols Routing protocols are the legislators of the Internet. 6. 6.6—Routers can communicate about routes dynamically using one of the two classes of routing protocols in Table 28-1. 6. the route with the lowest administrative distance wins. Enhanced Interior Gateway Routing Protocol (EIGRP).2—Once an administrator has configured a static route.2.2. AS numbers keep networks in manageable groups that allow routers to converge more quickly. The administrative distance for a static route is 1 by default. 2. In the routing table.2. routers must recalculate the routing tables using a dynamic routing protocol. so a 1 can only be bumped by a directly connected route with an administrative distance of 0. CCNA 2. You can configure a static route as a backup route if you give it an administrative distance that is higher than a dynamic route in the routing table. An AS number allows a network to represent itself as one unit.1—Routers use routing protocols to communicate with each other about networks and network locations. Examples of routing protocols include Routing Information Protocol (RIP).05_1587131749_DAY28. and Open Shortest Path First (OSPF).1—Routers choose a path over the network for a packet based on its destination IP address. Routing protocols can even have elections…kind of. You must not confuse a routing protocol with a routed protocol. 6.4–6.3—Routers achieve convergence when all routers share a common view of the network via their routing table. and 3 from CCNA 3 shed light on the routing protocols that are important to passing the CCNA exam. If the network changes.1. Routed protocols provide the information in a packet that allows the router to properly forward said packet. How do routers know the best path for a packet? Either you tell them with a manually configured static route or the router uses a dynamic routing protocol to find out about the network topology and build its own routing table. Link-state routing protocols build a topology of the entire network. They constantly discuss and define the rules for what data goes where and what paths the data must take. Distance vector routing protocols look at how far away a route is and the direction (vector) to reach it.2—Routing tables would be huge if there were no way to divide large networks into smaller groups of networks. IP and Internetwork Packet Exchange (IPX) are examples of routed protocols.2. the router adds that route to the routing table. Modules 6 and 7 from CCNA 2 and Modules 1. .1. Autonomous system (AS) numbers do just that with a 16-bit number assigned by the American Registry of Internet Numbers (ARIN). Module 6 6.2. Interior Gateway Routing Protocol (IGRP).

for example a company and an ISP. Border Gateway Protocol (BGP) is provided as an example of an exterior gateway protocol.3—Each of the routing protocols described in Table 28-2 function at the Internet layer of the TCP/IP model. and reliability OSPF Link-state Nonproprietary protocol that updates only when there is a change in topology EIGRP Hybrid Cisco proprietary protocol that uses both link-state and distance vector features and multicasts updates on 224.3.qxd 20 7/28/06 8:53 AM Page 20 31 Days Before Your CCNA Exam Table 28-1 Distance Vector and Link-State Protocols Distance Vector Link-State Routers send periodic updates of Routers send link-state advertisements (LSAs) to update other routers.4—Table 28-2 shows how autonomous systems are able to communicate. load.3. 6. If two networks. Routers see only neighboring routers. Table 28-2 Routing Protocols Protocol Name Type Description RIP Distance vector Broadcasts updates every 30 seconds and uses hop count as the metric with a maximum of 16 IGRP Distance vector Cisco proprietary protocol that broadcasts updates every 90 seconds and uses a composite metric of bandwidth. .05_1587131749_DAY28.1—When a router receives a packet on a port.0.3.0. they can use BGP on their gateway routers to exchange information about directly reachable networks. Routers use the LSAs to build a full topology of the network. The router uses the routing table to determine the best path for the packet and forwards it out the appropriate port. delay. To develop a full loop-free topological database requires more memory than a distance vector protocol requires of a router. it first looks at the destination address and compares it to its routing table. Routers use the Shortest Path First (SPF) algorithm and LSAs to build a shortest path tree as well as a routing table. 6. distance vector Used to route between autonomous systems 6. have different administrators and separate interior routing protocols. Routers flood LSAs only when there is a topology change. Routers use a metric to determine the best path for a route and build a routing table.10 BGP Exterior. the entire routing table to neighbors.

Module 7 7. A router can accomplish this by sending out the maximum hop count for a route as soon as it sees that the network is unreachable. RIP will identify a network as unreachable if it has a hop count over 15. distance vector routing protocols update only on a set interval. a router ignores its regular schedule and shoots out the poisoned route information as soon as it notices that a network is down.1. lies in the routing met- ric. Routing updates occur every 30 seconds with RIP. 7. A router can also prevent loops by poisoning a route for a network that has gone down.3. they can form a loop. Routing updates occur every 90 seconds with IGRP. A router on the network may not receive an update that a link is down and proceed to advertise that it can get to the network.3—The key to finding the proper path. IGRP focuses on speed as the main reason to use a particular route.1. it just means that all routers know about the change. Distance vector routing protocols monitor the distance a packet travels as it passes over the network to avoid this type of loop. 7.3. but IGRP can also be configured to use load and reliability. If this router is able to update other routers with this information. If these routers do not exchange routing tables quickly enough in a changing network.1. The maximum hop count of 16 ends the routing loop. This does not mean that routers immediately remove the route from the routing table. Each time a router running RIP receives an update. The default metrics used by IGRP are bandwidth and delay. you could have a loop. Split horizon prevents this type of loop when it states that routerA cannot receive an update that concerns routes that routerA originally advertised.1—Linksys home router supports RIP. With route poisoning and triggered updates. Typically.1. This process is aptly named route poisoning.1–7. the packets destined for the network could continue to pass around the network continuously. Routers implement a holddown timer that causes them to wait a set amount of time before actually removing a route from the routing table. . it adds a hop to the route to represent itself in the path to the destination.4–7. RIP is a distance vector routing protocol that implements split horizon and holddown timers.2. 7. RIP tracks a packet with hop count and deems a network unreachable if it appears over 15 hops away.1 and 7.7—If routerA updates two connected routers that network1 is down but then accepts a later update from one of those same routers that network1 is reachable. as mentioned previously.05_1587131749_DAY28. Components of a routing metric could be any of the following: ■ Internetwork delay ■ Bandwidth ■ Load ■ Reliability ■ Hop count Routers using a distance vector routing protocol exchange routing tables with neighbors to learn the metric and best path.qxd 7/28/06 8:53 AM Page 21 Day 28 21 CCNA 2. This problem is avoided with triggered updates. RIP uses only hop count as a metric to consider a path. This could cause routing issues if a network goes down and a router has to wait 30 seconds to send its next update.2—IGRP is also a distance vector routing protocol. This scenario is possible because one of the connected routers may be getting old information from another part of the network originally sent out by routerA. and for that matter many tombstones as well (bad joke).

Routers can learn about other networks through static and dynamic routes. In addition to the topological database. When a network changes.qxd 22 7/28/06 8:53 AM Page 22 31 Days Before Your CCNA Exam 7.0. Flooding LSAs across a network can affect overall bandwidth on a network and cause each router to recalculate a full topological database. These areas communicate with a backbone area to reduce routing protocol traffic and routing table size.2. System routes are between networks inside of an autonomous system.2–2.2.” and Day 22. Module 7.255. 2. 2.1—OSPF is a nonproprietary link-state protocol that allows you to control the flow of updates with areas. a network using a link-state protocol must be broken up into small enough areas to maintain network efficiency and use routers with sufficient memory and processing power. but LSAs remain the key way that link-state protocols discover information across the entire network. “Evaluate the TCP/IP Communication Process and Its Associated Protocols. These LSAs allow the router to create a topological database of the network. build the shortest path tree. For this reason.255. but for traffic destined outside of the immediate network an administrator can add a default route.2. You will cover IP addressing and VLSM on Day 27. RIP version 2 adds authentication and the ability to send a subnet mask with routing updates. and use the tree to build the routing table.1.2.1–2.6—Table 28-1 implies that link-state routing protocols send updates only when the net- work changes.3.0. RIP version 1 broadcasts updates on the address 255.9.” is a distance vector routing protocol that uses hop count as a metric and implements both holddown timers and split horizon.3.4—OSPF-enabled routers are true to their link-state definition in that they maintain a full loop-free topological database of the network. and exterior routes. use the Dijkstra algorithm to determine the shortest path for each network. Exterior routes define access to networks outside of an autonomous system. OSPF proves itself a good choice for a large network because unlike RIP it allows more than 15 maximum hops and large networks can be divided into areas. a router will flood LSAs on a specific multicast address across the specified network area. This means that RIP version 2 supports variable-length subnet masks (VLSMs) and classless interdomain routing (CIDR).1. Module 2 2. split horizon. Interior routes are between networks that are connected to a router and have been divided into subnets. Link-state protocols actually send little hellos periodically to obtain information about neighboring routers. and poison reverse.3—RIP. CCNA 3.7—All routers on the Internet cannot contain a route for every network that exists. A default route provides a destination for a router to forward all packets for which it does not have an entry in its routing table.05_1587131749_DAY28. 1. Module 1 1. system.3 and 7. as mentioned previously in “CCNA 2.2.” Another difference between RIP versions 1 and 2 is in how each protocol sends updates. This is a partial truth. IGRP increases its stability as a routing protocol by using holddown timers.2.1–1. Sorry.255. “Design an IP Addressing Scheme to Meet Design Requirements.4—IGRP can advertise interior. whereas RIP version 2 more efficiently multicasts on the Class D address 204. each . CCNA 3.

0.7—The OSPF process starts with hello packets to find neighboring routers and develop adja- cencies. To avoid a single point of failure.2. EIGRP also supports VLSM. Routers first determine if they are on a point-to-point link or multiaccess link.2. 2. A router running only IGRP will see EIGRP routes as IGRP routes.5. If you were to run OSPF on a fiber network.2. a DR and BDR election occurs. OSPF-enabled routers also elect a designated router (DR) and backup designated router (BDR) as central points for routing updates.qxd 7/28/06 8:53 AM Page 23 Day 28 23 OSPF-enabled router maintains a unique adjacency database that tracks only neighboring routers. Once adjacencies exist between neighbors. If the connection is broadcast or point-to-point.1. Once the topological databases are complete. or nonbroadcast multiaccess networks such as Frame Relay elect a single router called the DR to handle updates. and rapid convergence through LSAs are key features of OSPF. This means that each router would be a neighbor to every other router. CCNA 3. Each router then will have two adjacencies: one for each directly connected neighbor. Module 3 3. Routers that are connected on broadcast multiaccess networks like fiber. The contents of the hello packet include the following: ■ Version ■ Type ■ Packet length ■ Router ID ■ Area ID ■ Checksum ■ Authentication type ■ Authentication data 2. the packets default to 30 seconds. a bandwidth-based metric. Ethernet.0. OSPF avoids a network of neverending neighbors with an election. all routers would technically be connected on the fiber ring to each other.1—EIGRP and IGRP routing protocols function seamlessly together despite the fact that EIGRP offers multiprotocol support and functions as a hybrid routing protocol. VLSM support. whereas IGRP does not. . the hellos default to 10 seconds. 2. the routers forward LSAs and add information to their topological databases. and if the connection is nonbroadcast multiaccess (NBMA).05_1587131749_DAY28.6—Those little OSPF hello packets typical to link-state protocols go out over the multicast address 224.5—The OSPF adjacency databases are just great if you happen to be working with a Cisco Academy router pod with four routers each connected with point-to-point connections. Periodic hello packets can alert routers to a change in the topology that would restart the process. the routers use the SPF algorithm to create the SPF tree and then a routing table. a loop-free SPF tree. they also elect a BDR. If they are on a multiaccess link.

qxd 24 7/28/06 8:53 AM Page 24 31 Days Before Your CCNA Exam 3.1. EIGRP uses the reliable transport protocol as its own proprietary means of sending updates. EIGRP uses a neighboring table in the same way that OSPF uses an adjacency database to maintain information on adjacent routers.1.1. 3. or feasible successor routes. are kept only in the topology table. however. ■ Multiple network layer support—Rather than rely on TCP/IP to send and receive updates. In the topology table. Backup routes.10 to communicate with neighbors ■ Acknowledgment—Hello packets without data sent to acknowledge receipt of a message . In the topology table.2—As a hybrid multiprotocol routing protocol.4—Advanced features of EIGRP that set it apart from other distance vector routing protocols include: ■ Rapid convergence—EIGRP uses the DUAL finite-state machine (FSM) to develop a full loop-free topology of the network allowing all routers to converge at the same time.5—EIGRP uses five different types of packets to communicate with other routers: ■ Hello—Sent on 224. and external routes come from other routing protocols and outside the EIGRP AS. EIGRP also maintains a topology table that contains routes learned from all configured network protocols. Like OSPF. and enter it into the routing table. EIGRP uses functions from both link-state and distance vector protocols. EIGRP. If a network goes down and there is no feasible successor.3 and 3. EIGRP collects multiple databases of network information to build a routing table. EIGRP can also tag routes as internal or external.0. EIGRP has a modular design that uses protocol-dependant modules (PDMs) to support other routing protocols. Internal routes come from inside the EIGRP AS. IPX. 3. where ready-to-use routes are identified as passive and routes that are being recalculated are identified as active The neighbor and topology table allows EIGRP to use DUAL to identify the best route. ■ Efficient use of bandwidth—EIGRP.1. the router sets the route to active. EIGRP defines the following fields: ■ Feasible Distance (FD)—The lowest cost to each destination ■ Route Source—The router identification number for externally learned routes ■ Reported Distance (RD)—A neighboring router’s reported distance to a destination ■ Interface Information—Which interface to use to reach a destination ■ Route Status—The status of a route. sends out partial updates and hello packets. or the successor route. but these packets go only to routers that need the information. ■ Support for VLSM and CIDR—EIGRP sends the subnet mask information allowing the network to be divided beyond default subnet masks.0. ■ Independence from routed protocols—EIGRP supports IP. so changes to reflect revisions in the other protocols have to be made only to the PDM and not EIGRP.05_1587131749_DAY28. sends query packets out to neighbors. uses a distance vector diffusing update algorithm (DUAL) to recalculate a topology. and AppleTalk. like OSPF. EIGRP also develops neighboring relationships with other routers. and begins to rebuild the topology.

EIGRP-enabled routers build a topology table that contains and uses the DUAL algorithm to select the successor routes that will populate the routing table. . If a link goes down.6—As described in CCNA 3 Module 3. Summary Make sure you know the difference between a distance vector routing protocol and a link-state protocol. You can focus on the commands on a later day. you might flip through pages 388–450 and focus on the details of routing protocols.qxd 7/28/06 8:53 AM Page 25 Day 28 ■ Update—Used to update new neighbors so that they can in turn update their topology ■ Query—Used to gather information from one or many neighbors ■ Reply—Sent as response to a query packet 25 3. routing protocols as well. Second Edition nearby. you know how it is possible for the Internet to function and send so much data to so many hosts. If you happen to see a copy of CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study. If you understand routing protocols.05_1587131749_DAY28. This process and the DUAL algorithm enable EIGRP to achieve rapid convergence.1. the DUAL algorithm selects a feasible successor from the topology table and promotes it to the successor route. If there is no feasible successor. It is not uncommon for the CCNA exam to test your understanding of routed vs.2. exam #640-801).1. EIGRP recalculates the topology table.

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2. Each octet contains an 8-bit binary number like those shown in Table 27-1. and even the recording industry have taken great interest in the TCP/IP communication process. 10. Sometimes you will need to convert an IP address to its binary format when developing an IP addressing scheme for a network. Table 27-1 shows the powers of 2 for each bit from left to right and the decimal equivalent in the other section.5 and 1.2. “Design an IP Addressing Scheme to Meet Design Requirements.2.10—A 32-bit IP address is made up of four sets of numbers.06_1587131749_DAY27. Table 27-2 shows the rules for the AND operator and gives an example of applying an AND operation to an IP address and subnet mask to determine the network address. You will quickly review some concepts from Day 31.” as well as learn new information. Module 1 1. When a router receives an IP address in a packet.” CCNA 1.6—Understanding binary is important in order to understand IP addressing. video game developers. .2. “Describe Network Communications Using Layered Models. Decimal to binary conversion requires that you determine what bits contain a 1 and what bits contain a 0. Modules 1. and 1.qxd 7/28/06 8:53 AM Page 27 Day 27 Evaluate the TCP/IP Communication Process and Its Associated Protocols Network administrators. 2.7. Table 27-1 Binary to Decimal Conversion Bits and Powers of 2 Decimal Equivalent 1 128 1 64 1 32 1 16 1 8 1 4 1 2 1 1 128+64+32+16+8+4+2+1 = 255 1 128 0 64 0 32 1 16 0 8 0 4 1 2 1 1 128+16+2+1 = 147 0 128 1 64 1 32 0 16 0 8 0 4 1 2 0 1 128 64 32 16 8 4 2 1 1 128+2+1 = 131 1.2. 9. and 11 from CCNA 1 and Modules 8 and 10 from CCNA 2 outline the TCP/IP process and the associated protocols. Look at how the two columns relate and see if you can complete the last two rows. 1. Boolean logic compares two numbers and provides a result based on the AND operator. the router uses Boolean logic to compare the IP address to the subnet mask and determine the network address. Expect more on IP addressing on Day 22. TCP/IP is the postal system that allows devices on the Internet to differentiate between one host and the next.9. or octets.

168. SMTP.qxd 28 7/28/06 8:53 AM Page 28 31 Days Before Your CCNA Exam Table 27-2 Using the AND Operator to Determine a Network Address AND operator IP Address and Subnet Mask to Network Address 0 AND 0 = 0 IP address 192.168. but the OSI model is often used in academic and theoretical situations because it further divides the networking process.1. Table 27-3 The TCP/IP Model Versus the OSI Model.06_1587131749_DAY27. The application layer includes protocols such as FTP.7–9.11111111.6 and 2. as well as IEEE specifications for physical media. To identify networks and get information to hosts. TFTP. TCP and UDP operate at the transport layer. PPP.00000001.1.1.00000001.7 0 AND 1 = 0 IP address 11000000. Module 9 9. and FDDI. ATM. routers use the Internet Protocol (IP). 9.3.2. Module 2 2.255.7—Table 27-3 summarizes the information presented from Day 31 about the lay- ers of the TCP/IP model as compared to the OSI model.1–9.00000111 1 AND 0 = 0 Subnet mask 11111111. This allows a router to keep a .6—As covered on Day 31. IP addressing goes beyond unique identification to provide grouping by networks.255. as well as the protocol data units (PDUs) used in each layer. IP operates at the Internet layer and includes Ethernet. however.11111111.3— The Internet is made up of thousands of internetworks connected by routers through various types of physical media.1. Frame Relay.00000000 Network address 192. and DNS.1.3.00000000 1 AND 1 = 1 Result Mask 255. MAC addresses work wonders on a LAN at Layer 2 to identify computers for switching. On multiple LANs divided by Layer 3 routers.10101000.10101000. the TCP/IP model is made up of four layers. and the Corresponding PDU TCP/IP Model OSI Model PDU 4 (application) Application (Layer 7) Data Presentation (Layer 6) Session (Layer 5) 3 (transport) Transport (Layer 4) Segments 2 (internet) Network (Layer 3) Packets 1 (network access) Data Link (Layer 2) Frames Physical (Layer 1) Bits CCNA 1. The TCP/IP model is the basis of the Internet.0 CCNA 1.0 11000000.

4—IP addressing is by default broken up into a set of classes that define the network and host portions.qxd 7/28/06 8:53 AM Page 29 Day 27 29 shorter table of network locations and not individual IP addresses.H. Table 27-5 provides as much information as will fit about address classes. The broadcast address for a network is where the host portion is made up entirely of binary 1s.N.H.168. Table 27-4 One Octet of an IP Address Bits and Powers of 2 1 128 1 64 1 32 1 16 Decimal Equivalent 1 8 1 4 1 2 1 1 128+64+32+16+8+4+2+1 = 255 So how does an IP address display information about the specific host and the network? Part of an IP address represents the host. The first few binary digits in an IP address define the default address class.N.H.0 192. Each host on a network has a 32-bit address that is represented in dotted decimal format. or the address on a network used to reach all hosts on that network.168. Table 27-2 provides you with an example of an IP address represented in both dotted decimal and binary formats.1. Know those first 8 powers of 2 and you will be able to diagram an IP address as binary or decimal. and part represents the network.H.2.1 to 192. 9.2. Table 27-5 Class A. Table 27-6 shows a network and broadcast address example. Table 27-6 Network and Broadcast Address Example Network Default Class C Binary Host All 0s Network Address Binary Host All 1s Broadcast Address Useable Hosts 192.H About 16 million 8 Class B 10 128–191 N. D.H 254 24 Class D 1110 224–239 H. converting binary IP addresses to decimal and back is all about the powers of two.168.H Multicast 28 Class E 1111 240–255 RESEARCH RESEARCH RESEARCH The Class A address 127. B.1.1.06_1587131749_DAY27. and E IP Addresses Class Binary Start 1st Octet Range Network (N) and host (H) Octets Number of Hosts Bits in Network Address Class A 0 1–126 N.1.535 16 Class C 110 192–223 N. C.255 192.0 192. The broadcast address.168.5—The address for a network cannot be assigned to a host.N. cannot be assigned to a specific host. dotted decimal is easier to read.0.168.254 .H. This is like putting the name of your city on an envelope to represent where your house is located.1.H 65. The network address for a specific network is where the host portion is made up entirely of binary 0s. It might also be good to practice adding those numbers in various combinations. As shown in Table 27-4. 9.0 is reserved for the loopback.0. Despite the fact that binary looks cooler.

“Design a Simple Internetwork Using Cisco Technology”). or subnetted in smaller subnetworks.0 to 192.7—There are no networks in the world with 1 router and 16 million hosts.168.0. Let’s say hostA broadcasts an ARP request and hostD has the matching IP address. When the lease expires.255 9. ■ DHCP—DHCP does not require you to enter information for each host that you add to the network.31.2. With IPv6.255.6 and 9.6—Hosts that are directly connected to the Internet require a unique public IP address. must be present for RARP to function. you can increase the subnet mask by borrowing bits from the host portion and create multiple smaller networks. Two hosts cannot have the same IP address on the Internet and expect traffic to route.0 to 10.16. Table 27-7 Private Network Addresses Class Address Range Class A 10. The same is true of a network of any size that does not need to use the address space it reserves.255. HostD will .0 to 172. Class A networks are always divided.5—You can assign a static IP address to a host. ■ Bootstrap Protocol (BOOTP)—BOOTP is a way for a host to use UDP to obtain an IP address as well as router and server information.3. DHCP requires only that you to enter a range (or pool) of IP addresses for the DHCP server to lease to a host. or the host can dynamically acquire an address.2.255 Class B 172. 9.0. If you have an entire class B network. As the replacement for BOOTP.255 Class C 192. Servers and network devices that provide services to hosts should have a static IP so that the hosts can find them. A RARP server. and we will cover subnetting in depth on Day 22.7—RARP finds an IP using the MAC address. usually the router. ARP occurs when a host has a destination IP address for a packet but needs to determine the MAC address to send the packet over the LAN.3. This is also possible with a class C network. As IP addresses become scarce. 9.255.3.2.0. the Internet has a potential 640 sextillion unique addresses. 9.qxd 30 7/28/06 8:53 AM Page 30 31 Days Before Your CCNA Exam 9.255.1–9.3. the DHCP server can reclaim the address for other hosts. it is possible that 128-bit IP version 6 (IPv6) addressing will become the leading protocol on the Internet. You have to add an entry to the database on the BOOTP server for each host on the network. 128-bit IPv6 addresses consist of eight 16-bit sections separated by a colon and represented in hexadecimal format. private or internal addresses are available as outlined in RFC 1918 and Table 27-7. so Address Resolution Protocol (ARP) finds a MAC address using the IP address.06_1587131749_DAY27.0. For networks that are not connected to the Internet or that are using a proxy (covered on Day 20.168.8—The IP address discussion to this point has been about 32-bit IP version 4 (IPv4) address- ing. Three common methods that hosts use to obtain an IP address automatically are as follows: ■ Reverse Address Resolution Protocol (RARP)—Hosts can use RARP to associate a MAC address to an IP address.

HostA can then add this information to its ARP table and send the packet with the MAC-IP pair.qxd 7/28/06 8:53 AM Page 31 Day 27 31 respond with its MAC address.1.4—IP is a Layer 3 routed connectionless protocol. A packet will maintain the same destination IP address as it travels across LANs.1. 10.06_1587131749_DAY27.5—The following fields make up an IP packet: ■ Version—Defines the format of the packet ■ IP Header Length (HLEN)—Length of all header information ■ Type of Service—Importance level as assigned by an upper-layer protocol ■ Total Length—Length of the entire packet ■ Identification—The sequence number ■ Flags—Identifies if the packet can be fragmented and if it is the last piece of a fragmented packet set ■ Fragment Offset—Used to assemble packet fragments ■ Time to Live (TTL)—The number of hops a packet can travel before being discarded ■ Protocol—Upper-layer protocol such as TCP or UDP ■ Header Checksum—Used to check the header ■ Source Address—IP address of sender ■ Destination Address—IP address of intended recipient ■ Options—Support for options like security ■ Padding—Used to keep the IP header a multiple of 32 bits ■ Data—Encapsulated information from upper layers. CCNA 1. A circuit-switched connection sends packets in order across a physical or virtual circuit. Remember that a Layer 3 packet is encapsulated in a frame for Layer 2 transport across a LAN. If hostD is not on the local LAN. IP is a packet-switched process. an upper-layer protocol will request retransmission. As a connectionless protocol. Module 10 10. Packet-switched communication can send packets along different network paths to be sorted and sequenced upon arrival at the destination.1–10. which can be up to 64 bits . If a packet does not reach its destination.1. IP is considered a best-effort delivery system because it does not verify that a packet has reached its destination. the router will recognize this and respond with its MAC address with the intent of forwarding the packet. but each router that views and forwards the packet will strip and replace the Layer 2 destination MAC address to get the frame across the LAN.

1. 8.2. Module 10 10.06_1587131749_DAY27. Module 11 11. CCNA 2.1–10. The TCP/IP transport layer can use TCP as a connection-oriented protocol.6—Although ICMP can send source quench messages. and RIP on port 520.1.7—Didn’t we already cover Module 11 on day 31? Yep. ICMP messages start with Type. If a router cannot deliver a packet. FTP on port 21. Examples of protocols that use TCP are TFTP on port 69. it is possible that a 1337hax0r (elite hacker) could send a number of SYN requests from a nonexistent IP address . In today’s networks. Examples of protocols that use TCP are HTTP on port 80. The TCP/IP transport layer can also use the connectionless UDP protocol. sliding windows. hosts use DHCP to obtain IP addresses. and Telnet on port 23. CCNA 2. SNMP on port 161. IP does not report errors in transmission.1. Module 8 8.1.9—As mentioned previously.2. Module 10 in CCNA 2 repeats information from Module 11 in CCNA 1 and adds the following information: ■ While a TCP connection is established using the three-way handshake. ICMP packets that cannot be delivered do not generate their own error messages to avoid congestion. it will provide an ICMP destination unreachable message with a specific code to identify why the destination is unreachable.1–8.9—ICMP also sends control messages to tell hosts about network conditions. positive acknowledgement. ICMP allows a router to send an error notification to the device that originally sent the packet. This is the job of the Layer 3 protocol Internet Control Message Protocol (ICMP). which features a three-way handshake.1–8. which does not feature acknowledgments or sequencing and broadcasts segments. Here are two quick para- graphs to summarize what Day 31 covered. and Checksum fields. The ping command uses an ICMP echo request to verify connections and waits to receive an ICMP echo reply.2. the real flow control happens at the transport layer with TCP.1–11. The TCP/IP transport layer creates a session between hosts using segments as the PDU and either standard ports (1023 and below) or nonstandard ports (above 1023). Code. Different types of control messages are as follows: ■ ICMP redirect/change requests—Allow a gateway to inform a host about a better route ■ ICMP timestamp messages—Allow a host to exchange time information with a remote host and identify the delay across the network for time synchronization ■ ICMP source quench messages—Allow a gateway to notify a host if the network is congested and to temporarily slow transmission Hosts can also use ICMP to obtain an IP address to discover the subnet mask and to discover a router.2. and segment sequencing.qxd 32 7/28/06 8:53 AM Page 32 31 Days Before Your CCNA Exam CCNA 1.

This type of denial-of-service (DoS) attack could prevent a device from responding to legitimate requests.06_1587131749_DAY27. ■ A host can provide services simultaneously on two different ports. It is important to understand the hierarchy and grouping of Layer 3 IP addresses and networks as well as the Layer 4 flow control and reliability of TCP. Second Edition (ISBN: 1587200791) might help you to refine this knowledge. Pages 123–145 in the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study. These repeated requests could cause a device to wait for an acknowledgement and use all of its resources. . exam #640-801). ■ Port number assignment occurs at Layer 4 of the OSI model.qxd 7/28/06 8:53 AM Page 33 Day 27 33 to this host. and MAC address assignment occurs at Layer 2. and dynamic ports (49152 to 65535). ■ The process in sliding windows where TCP requests that a host resend information is called positive acknowledgement and retransmission (PAR). An example might be a web server that provides HTTP access on port 80 at the same time as Telnet access on port 23. Summary From the initial ARP request to find a destination IP address to the last acknowledgement of a TCP segment. the TCP/IP process assists Internet communication worldwide. registered ports (1024 to 49151). Ignore the subnetting questions until after Day 22. IP address assignment occurs at Layer 3. ■ A more concise definition of port number ranges includes well-known ports (0 to 1023). Software exists that can recognize and repel such an attack.

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routing. Module 1 1.2 and 1. which runs hardware diagnostics. and where interfaces temporarily store packets that the router is forwarding. FDDI. On this short day you could definitely knock out another practice CCNA test when you have finished reading. Modules 1 and 2 from CCNA 2 describe the various bits and pieces that make up network devices and how Cisco IOS software works with the hardware. ■ Random-access memory (RAM)—Where the router stores routing table information and the running configuration. and can contain a reduced version of the IOS for troubleshooting. You need a straight-through cable to connect a router to a switch and a crossover cable to connect a router directly to a computer or another router. ■ Nonvolatile random-access memory (NVRAM)—Stores the startup configuration and does not lose data when the router is powered down. RAM loses all data when the router is powered off. 1.qxd 7/28/06 8:53 AM Page 35 Day 26 Describe the Components of Network Devices Although protocols and software determine the logical layout and provide instructions for network processes. The CPU bus is used specifically for the CPU to transfer data to memory and back.7—The following list describes the three ways (aside from power) that you can physically connect to a router: ■ LAN connections—Ethernet. ■ Interfaces—Connections from routers to other devices for networking and management. The RAM can be upgraded with dual inline memory modules (DIMMs). ■ Read-only memory (ROM)—Holds the ROM monitor. ■ Buses—The system bus is the internal means of communication between the CPU and other internal components. and Token Ring technologies connect to a LAN interface. ■ Flash—Stores the full Cisco IOS software and can be upgraded with single inline memory modules (SIMMs) or a Personal Computer Memory Card International Association (PCMCIA) card. loads the IOS. . The ROM can only be upgraded by replacing the actual chip.2. CCNA 2.3–1. and interface control.2. including initialization.2.1.07_1587131749_DAY26.1—The internal components of a router are as follows: ■ Central processing unit (CPU)—Runs instructions from the operating system. the engine of any network is its hardware. ■ Power supply—Can be modular and supplies power to the router.

which is RAM/zipped.1–2. An IOS image is named using a format that identifies first the platform. ■ Management ports—Serial EIA-232 interfaces provide an out-of-band way to connect a terminal to the router and troubleshoot in a text-based session. Once you are logged in. A quick and almost poetic way to remember the standard terminal configuration is to recall 9600-8-none-1-none. You can also configure a router by dialing to a modem connected to the AUX port. amount of RAM. Initially. which can be a channel service unit/data service unit (CSU/DSU) or a modem.5—When you start a router. The prompt is a > or ROMMON> ■ Boot ROM—A paired-down version of the IOS used to copy a new image to flash memory ■ Cisco IOS—The full Cisco IOS image stored in flash . to connect to your router as the data terminal equipment (DTE) device.3—You can manage a router in a text-based terminal using a command-line interface (CLI). The following list explains the components of the Cisco IOS image name C2600-is-mz: ■ C2600 refers to the platform. it can enter three different operating environments.1. and amount of flash memory. You can look at this information in the CLI under user EXEC mode by typing show version to see the existing image name. the CLI has two key modes: ■ User EXEC mode does not allow configuration changes and is represented by the hostname> prompt.1. The service provider uses the DCE device to set clocking on the connection.qxd 36 7/28/06 8:53 AM Page 36 31 Days Before Your CCNA Exam ■ WAN connections—If you choose to connect to a WAN. which is Cisco 2600 series. 2. ■ is refers to the feature set. Typically. you connect physically to gain access. then the feature set. Module 2 2. the service provider will use a data circuit-terminating equipment or data communications equipment (DCE) device. ■ mz refers to the image location/compression. ■ Privileged EXEC mode gives you administrative access to all the configuration modes and is represented by the hostname# prompt. as follows: ■ ROM Monitor (ROMMON)—Used for password recovery and diagnostics. 2. CCNA 2.07_1587131749_DAY26.1.4—Software compatibility with hardware comes into play when deciding to upgrade the Cisco IOS image on a router.1. and lastly where the image will run and if it uses compression. It is important to check your router to make sure that it has enough RAM and flash memory to support a new IOS image. which is IP Plus. you can use a rollover cable and a terminal emulation program (such as HyperTerminal) on a desktop computer to connect to the console port and manage a router. but once networking and virtual terminal access is configured you can also telnet to a router.

2. Once the IOS image is loaded. open HyperTerminal and make sure that the settings are 9600-8-none-1-none.2. If there is no configuration file in NVRAM. Second Edition (ISBN: 1587200791) and. Next to the AUX port is an OK LED that illuminates when the system has initialized.07_1587131749_DAY26. the IOS software starts the setup dialog. of course. a TFTP server. The location of the IOS image can be specified in the configuration register. It might also help to look at many of the questions in pages 199–205 and 259–274 in the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study. or ROM.2. Summary Your experience with actual routing hardware from the Academy and knowledge of how the software and hardware in a router relate will help with any CCNA questions covering this objective.4—For a console TIA/EIA-232 port connection on a router. it loads the configuration file from NVRAM.qxd 7/28/06 8:53 AM Page 37 Day 26 37 2. to take a quick practice CCNA exam today if you have time. . 2. the IOS software searches for a TFTP server to load the configuration file. If there is no TFTP server.2—A router has an LED light next to each interface that should blink to show activity if the interface is working properly.2. exam #640-801).1—When a Cisco router powers up. you use the RJ45 connector on one end of your console cable and the RJ45 to DB-9 adapter and serial COM port on your desktop. Once you have everything connected. it first performs a power-on self test (POST) and then it loads a bootstrap and initializes the Cisco IOS image from flash.

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If a frame does not match its own frame check sequence (FCS). ACLs can provide instructions for a router to accept or deny a packet. ■ A router checks ACL statements in the order in which the ACL rules have been entered in the configuration. The router stops at the first match and does not check any other statements.8—The following are three main types of collisions that can occur on a network: ■ Local collision—Occurs when a network card notices that the receive (Rx) wires detect a signal at the same time the transmit (Tx) wires attempt to send data. “Develop an Access List to Meet User Specifications. All hosts then use the backoff algorithm to wait a random amount of time before attempting to retransmit. “Troubleshoot an Access List. ■ Late collision—Occurs after the first 64 bits of data have been transmitted for a frame.” CCNA 1.” Day 10. As an administrator. this is considered a cyclic redundancy check (CRC) error. Key points to remember about an ACL include the following: ■ To revise an ACL. “Describe Network Communications Using Layered Models. CCNA 2.6–6.2—If you configure an ACL on a router.2—CSMA/CD provides the rules for how a device can communicate on an Ethernet network. These frames are usually collision fragments.2. and port number. The Layer 2 network card cannot recognize this type of collision and must rely on the upper layers to request retransmission. upper layer protocols. Module 6 from CCNA 1 and Module 11 from CCNA 2 describe collision detection and Layer 3 ACLs. You will cover ACLs again on Day 19.qxd 7/28/06 8:53 AM Page 39 Day 25 Evaluate Rules for Packet Control The rules of Carrier Sense Multiple Access/Collision Detection (CSMA/CD) at Layer 2 and access control lists (ACLs) at Layer 3 help control how data can be sent across a network.2. An ACL can match a packet by source.1. “Implement an Access List.08_1587131749_DAY25. . Module 11 11. you can assign one outbound and one inbound ACL per port for each protocol. A runt is a frame that is less than the minimum size of 64 octets. As discussed on Day 31.1. the router checks each packet that it processes against the ACL. A remote collision is likely the result of a local collision on the other side of a hub or repeater. 6. Module 6 6. If two hosts attempt to transmit at the same time. destination. a collision occurs and both hosts transmit until all devices have detected the collision. you must delete and recreate the entire ACL.1 and 11.” and Day 3.” a host listens to find out whether the network is available and then transmits data. The repeater would only regenerate a fragment of the collision and not the simultaneous Tx and Rx.2. ■ Remote collision—Occurs when a frame is too small. A frame that exceeds the maximum legal frame size causes a network diagnostic tool to report jabber on the connection.

0 states that the ACL should match the entire host.168.11111111 Result 192. and port.10101000. Named ACLs can be configured as standard or extended ACLs.0 can also be represented by the term any or host in an ACL. You should put a standard ACL as close to the destination of the traffic you are filtering as possible.0.0.08_1587131749_DAY25.168.00000000 *A 1 means ignore. Table 25-1 A Wildcard Mask to Identify What an ACL Should Match Decimal Binary* IP Address 192. and a 0 means match Using the information in Table 25-1. protocol. A standard ACL cannot look at where the packet is going.00000001.10101000. 11. wildcard masks serve an entirely different function from subnet masks.0 11000000.0. A wildcard mask is not the opposite of a subnet mask and serves an entirely different function. destination. or named ACL.0. you need to choose to make a standard.2.0 to 192.255.2. Extended ACLs use the number range 100 to 199. ■ Extended—With an extended ACL. A binary 1 says that the bit can be ignored.2. The wildcard mask 0. ■ Named—Named ACLs do not use a range of numbers because the name is the identifier.0.1. . you can check the source. We will cover configuration on Day 10.1.00000000.1–11.00000000.255 00000000. who is sending the packet. Table 25-1 provides an example. by looking at the destination address).0.00000111 Wildcard Mask 0. Do not look for a relationship between wildcard masks and subnet masks. You pair a wildcard mask with an IP address and use binary to identify what part of the address should be matched. but it can look at who sent it.168.4—With a wildcard mask you can tell the router exactly what IP address or IP address grouping you want to filter.1.7 11000000. This allows the extended ACL to filter the traffic by looking at where it is headed (that is.168. Named ACLs can be altered without deleting the entire ACL and recreating it. 11.qxd 40 ■ 7/28/06 8:53 AM Page 40 31 Days Before Your CCNA Exam At the end of every ACL there is an implicit deny that drops any packets that did not match an entry.1. but you can add statements only to the end of a named ACL. The following key points about each should help you choose wisely: ■ Standard—This type of ACL uses the number range 1 to 99 and checks only the source address—that is. 11. extended.1.4—You should put an extended ACL as close to the source of the traffic you are filtering as possible. the ACL must match the range 192.00000001. Always consider a wildcard mask in binary form. 0.3—When you create an ACL. but remember that you need to add a permit statement at the end if you want a packet that matches no specific statements to be forwarded. A binary 0 in a wildcard mask says that the bit should be matched.

10.qxd 7/28/06 8:53 AM Page 41 Day 25 41 Summary Today you reviewed how a network can control the flow of data at Layer 2 with CSMA/CD and at Layer 3 with ACLs and wildcard masks. You will review ACL theory and configuration on Days 19. . In the meantime. exam #640-801). You may also want to read through pages 456–467 in the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study. Second Edition (ISBN: 1587200791). ponder this question: Should ACLs give you more control over a network or lessen the need to control a network? Taking a Networking Academy CCNA curriculum practice test will help you make this assessment.08_1587131749_DAY25. and 3.

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1. T3. T1. and 5 from CCNA 4 discuss the key characteristics of WANs. WAN connection speeds can range from bits per second to gigabits per second in full duplex. 4. and WAN connections and then further explore WAN characteristics on Day 18. Module 1 1. WANs often provide access over serial interfaces at lower speeds than a LAN. digital subscriber line (DSL).2—In CCNA 2 Module 1.” Module 2 from CCNA 1. and 1. E1. you will almost always coordinate with a com- munication service provider such as a local phone company. The phone company will ask you to connect your router.7—Imagine that your box of connectivity equipment has just arrived in the mail and it is time to connect to the WAN. or private LANs across a large distance. CCNA 4.4—When you design a WAN. CCNA 1.1. Module 2 2. and routers often act as a gateway from your LAN to a WAN. You now need to be familiar with a few new WAN connectivity terms. and Modules 2.qxd 7/28/06 8:54 AM Page 43 Day 24 Evaluate Key Characteristics of WANs A WAN connection allows you to link office. The port in your building that the phone company installed is called the demarcation point.3. You can connect to a WAN using a modem. you connected to the WAN and can now surf happily. Routers. WAN protocols.09_1587131749_DAY24. Module 2 2.2. A common physical connection type for a DCE/DTE interface is a High-Speed Serial Interface (HSSI). Your DTE will likely connect through a CSU/DSU (could be a modem) as the provider’s data circuit-terminating equipment (DCE).1.2.7. The connections and protocols specific to a WAN operate at OSI Layers 1 and 2. school.1. Synchronous Optical Network (SONET).1 and 2.1. Integrated Service Digital Network (ISDN). or central office (CO). Your HSSI connects to a CSU/DSU to provide proper . 1. and communication servers play an important role in WAN design. and the provider will set the clocking with the DCE. Today you quickly review WANs. or E3. The cabling between you and the CO is often called the local loop or last mile. Module 1 from CCNA 2. These physical and data-link standards and protocols are different for a WAN than for a LAN. “Choose WAN Services to Meet Customer Requirements. You should know that you are connected to the provider’s nearest exchange. Frame Relay. CCNA 2. geographically separated area.1. which can also be referred to as customer premises equipment (CPE) and the data terminal equipment (DTE). 1.1. 3. modems.7—WANs operate over a large.

1. The Internet is an example of a connectionless PSN where each packet contains full addressing information. A modem can also serve this purpose by modulating and then demodulating the signal in order to pass digital information over an analog line.4—A WAN connection uses a Layer 2 frame to encapsulate data. For data communication. you can use a dedicated circuit and buy a fractional T1/E1 through T3/E3 or DSL or you can instead choose a switched circuit as one of the following: . Table 24-1 WAN Physical and Data Link Layer Standards Physical Data Link EIA/TIA-232 64 kbps Point-to-point Cisco HDLC. the exchange of the local carrier switches circuits to create a continuous circuit between you and the person you are calling.09_1587131749_DAY24. Frame Relay switches create a virtual circuit (VC) between communicating hosts that exists only when the frame is being transferred. LAPB EIA/TIA-449/530 Up to 2 Mbps Packet switched X.3—Table 24-1 displays the physical layer and data link layer standards for a WAN.1. The control field identifies one of the following three types of frames: ■ Unnumbered frame—This frame is for line setup messages. Frame Relay is an example of a Layer 2 WAN connection-oriented PSN where the route is determined by switches and each frame carries an identifier called a data-link connection identifier (DLCI). The phone system is considered a circuit-switched system.1. A phone call requires continuous connectivity.21 Synchronous digital 2.5—When you make a phone call. it is possible for many computers to share a connection and take turns requesting and receiving data as packets. and protocol field. The most common WAN encapsulation uses the HDLC standard. ■ Information frame—This frame holds data. When a virtual circuit needs to exist forever. and the frame ends with a flag field. 2.35 48 kbps X. A data field and FCS field follow. Following the starting flag field is a header field that includes the address.1. You can refer to a temporary virtual circuit as a switched virtual circuit (SVC). but a person who surfs the Web only needs to connect in short bursts to get and receive new information. PPP and Cisco HDLC have an extra field that identifies the network layer of the encapsulated data. 2.25.qxd 44 7/28/06 8:54 AM Page 44 31 Days Before Your CCNA Exam transmission of the signals over the link. it is called a permanent virtual circuit (PVC). ■ Supervisory frame—This frame controls data frame flow and can request retransmission if an error occurs. A connection that shares capacity by switching packets for many nodes is called a packet-switched network (PSN). An HDLC frame starts and ends with a flag field. Frame Relay EIA/TIA-612/613 HSSI up to 52 Mbps Circuit switched ISDN V. 2.6—To connect to a WAN. control. PPP.

qxd 7/28/06 8:54 AM Page 45 Day 24 ■ Circuit switched in the form of ISDN or the plain old telephone service (POTS) ■ Packet switched in the form of X. If the packets fulfill both conditions. the network of Frame Relay switches moves the data to its destination. CCNA 4. and if so. We will cover more of these terms on Day 18. the router sets up the call and all traffic will be sent over the link until no more interesting traffic is sent and the idle timer timeout period completes. V. Frame Relay switches act as a DCE for a router.1. your router is the DTE and the provider allows you to connect to the DCE.1. and the ISDN connection allows for a PPP-encapsulated link. Module 5 5. Modems auto-sense the clocking from the service provider line.35. ISDN bearer (B) channels carry data at 64 kbps for each channel.25 or Frame Relay ■ Cell switched as Asynchronous Transfer Mode (ATM) 45 If you choose packet switching and if your bandwidth requirements are low. Your DTE connection to the CSU/DSU will be through a serial connection using one of the following standards: EIA/TIA-232.3. 4. Both a modem and a CSU/DSU can function as DCEs and are the entrance point to the service provider network. Usually you subscribe to a network of trunked Frame Relay switches owned by a public carrier. but in the context of dial-on-demand routing (DDR) interesting traffic is network activity that causes a router to connect to a network. connection-oriented. and HSSI. CCNA 4. Module 4 4. A router that is set up for DDR will receive packets and first check to see if the packets should be forwarded to the DDR link. The ISDN delta (D) channel is used to set up the call and for signaling.2.1 and 3. X.1. you can save money if you request an SVC instead of a PVC. CCNA 4. The call with ISDN is faster than a modem.09_1587131749_DAY24. V. You can define a dialer-list on a Cisco router that tells the router what traffic should cause it to bring up a DDR link. Serial communication standards include RS-232-E. This digital connection allows you to exceed the 56 kbps bandwidth barrier of an analog connection.4—WAN serial communication requires that frames are sent one bit at a time over the wire. Module 1” under 1. . and EIA/TIA-530. data link layer WAN technology.7. but may need to be configured. HDLC encapsulating. Once the frame is forwarded from the DTE router to a Frame Relay switch. As mentioned in “CCNA 2. check to see if they meet the criteria for interesting traffic.1—Local carriers use ISDN to provide a digital connection on the local loop for a subscriber. EIA/TIA-449.1—Interesting traffic could be defined in many ways. With an SVC. Frame Relay would be a good choice. Module 3 3.1—If you were asked to name one packet-switched.1. the provider can allow you to share a physical link with other subscribers. A CSU/DSU typically is defaulted to auto sense it from the line.35.21.

LAN2 will also have a DLCI that identifies it on the Frame Relay network. The routers on LAN1 and LAN2 operate as Frame Relay access devices (FRADs). exam #640801). You then connect the LAN2 router to a nearby Frame Relay switch on the same phone company network. Your Notes . You learn more about these key WAN characteristics on Day 18.1. and types of WAN connections. The phone company uses its Frame Relay switches to then establish a packet-switched PVC across town for your two LANs. including its relation to the OSI model.qxd 46 7/28/06 8:54 AM Page 46 31 Days Before Your CCNA Exam 5. look over pages 488–510. First you call the phone company and connect your LAN1 router to their nearest Frame Relay switch. If you have CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study.09_1587131749_DAY24. Your LAN1 router will have a unique DLCI that identifies it on the Frame Relay switch network.2—You want to connect LAN1 to LAN2 across town using Frame Relay. Second Edition. Summary Today you reviewed a comprehensive definition for a WAN.

qxd 7/28/06 8:54 AM Page 47 Part II 23–18 Days Before the Exam— Planning and Design Day 23: Design a Simple LAN Using Cisco Technology Day 22: Design an IP Addressing Scheme to Meet Design Requirements Day 21: Select an Appropriate Routing Protocol Based on User Requirements Day 20: Design a Simple Internetwork Using Cisco Technology Day 19: Develop an Access List to Meet User Specifications Day 18: Choose WAN Services to Meet Customer Requirements .10_1587131749_Pt2.

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End-user devices (computers. Token Ring. Module 2 2. CCNA 1. and how to handle errors. 5.1. printers.6—Networks need a set of rules to determine how they communicate. The most common LAN technologies are Ethernet.1. peripheral devices. Key network devices that glue a LAN together include the following: ■ Network interface card (NIC)—Connects the host to a network and contains a MAC address ■ Repeaters—Simply regenerate the signal ■ Active hubs—Regenerate the signal and have multiple ports ■ Bridges—Two ports that maintain a MAC address table for hosts ■ Switch—Multiple ports that maintain a MAC address table for connected hosts ■ Routers—Connects a LAN to a WAN 2.1. Module 1 from CCNA 2. These terms include the following: ■ Bus—All devices connected to one arterial cable ■ Ring—Each host connected to two other hosts forming a ring ■ Star—All hosts connected to a hub or switch ■ Extended star—Hosts connected to a hub or switch that is in turn connected to a hub or switch ■ Hierarchical—Hosts connected to a hub or switch that is connected to another host or switch forming an extended star that is then connected to a proxy that handles traffic ■ Mesh—A direct physical link from each host to every other host 2. Important sections of the Cisco Networking Academy curriculum that cover LAN design are Modules 2. and 10 from CCNA 1. and so on) and network devices (cables. Network protocols control the type of connection. and so on). . 9.4—The terms to describe the physical topology of a network help you to explain how all of the devices are actually connected.1. how data is transferred. and Module 5 from CCNA 3. 8. These rules are defined as protocols. hubs. and FDDI.3—Networks contain two main types of devices.5 and 2.qxd 7/28/06 8:54 AM Page 49 Day 23 Design a Simple LAN Using Cisco Technology Previous days and topics about LANs spill together into LAN design with an additional focus on the Cisco three-layer hierarchical model.11_1587131749_DAY23. networking media. and network devices make up the main parts of a LAN. Computers. NICs.

If you are going to extend your LAN to its absolute maximum. Any group of devices that can cause a collision by attempting to communicate at the same time is in the same collision domain. 5. 5. 5.3u for 100 Mbps. and Xerox (DIX). Module 5 5. and have a maximum length of 500 meters over coaxial cable.11_1587131749_DAY23. Typically. Ethernet is implemented at the 100 Mbps (Fast Ethernet) level with Gigabit Ethernet as a backbone solution.3z for 1000 Mbps. Intel. or a hub to a PC.6—A repeater strengthens a signal to allow for greater cable and network distances. The IEEE specifications for Ethernet are 802. a router to a router. All devices are still in the same collision domain.1. A bridge can learn the MAC address of network hosts and determine whether or not to pass the signal to the separate segment. Bridges have only two ports. and Ethernet. .1.1.qxd 50 7/28/06 8:54 AM Page 50 31 Days Before Your CCNA Exam CCNA 1. a switch to a PC. If both ends of the cable are wired the same.1. A hub does little beyond concentrate the cables in a LAN to a central point.3 for 10 Mbps. and two (2) of the segments have no hosts on one (1) big collision domain.1—The physical layer of a LAN focuses on the media (actual cables and technology) used to connect the machines and send information.2—Ethernet was first implemented by Digital. the WLAN is in one collision domain (similar to a hub). and 802. and use twisted pair (100 meter limit) as the media for transmission. Category 5 unshielded twisted pair (UTP) carries most LAN signals today. This kind of cable allows you to connect a switch to a switch. 802. however. optical fiber.9—Bridges move beyond that barrier of simple.3—Details about the type of Ethernet implementation can be deciphered from the TIA/EIA standards. Many newer devices. 1000BaseT implementations are 1000 Mbps. Improperly set up wireless LANs (WLANs) can have security risks. Save that crossover for your old stuff.1. 5. but signals can be transmitted through coaxial cable. A network can only have five (5) segments connected with four (4) Layer 1 and Layer 2 devices. FDDI. 10Base5 implementations are 10 Mbps.1.1. or a router to a PC. senseless signal sending. baseband. only three (3) of those segments can have hosts attached. This will change as the cost to implement Gigabit Ethernet drops. 5. a hub to a hub. 5. both A or both B. baseband. You can use this kind of cable to connect a switch or hub to a router. Common technologies include Token Ring. are auto-sensing and therefore allow use of a straight-through cable where you once needed a crossover.5— At the end of an Ethernet cable is the RJ-45 connector. be sure to follow the 5-4-3-2-1 rule. you have a straight-through cable. cost is no longer an issue.8—LANs can be connected using wireless signals. a PC to a PC. WLANs are predominately connected using radio frequency (RF) to communicate between transceivers (devices that have both a transmitter and a receiver). Cost used to be a primary factor when deciding between a hub and switch. This EIA/TIA-specified. a switch to a hub. Because all networking devices see all signals.1. 5. but because the price of switches has decreased. clip-sporting piece of plastic comes in two flavors: T568A and T568B.7—Repeaters have just two ports and serve the purpose of doubling the length of a cable. eightwire. A hub is a multiport repeater. and wireless as well. you have created a crossover cable. If you wire A on one end and B on the other end (or vice versa).

Although routers identify hosts on a LAN using the MAC address. The MAC address that switches.3—Switches can learn the source and destination of traffic and create a virtual circuit between two hosts on a network. Module 8 8. In order to begin filtering.12—Peer-to-peer networks (ten or fewer computers) allow users to control access and resources individually. File and print sharing are the common configurations on a peer-to-peer network.2. a router uses the host’s Layer 3 IP address to forward data between networks.10—A switch is able to learn the MAC address like a bridge. This virtual circuit can then operate in full duplex and double the bandwidth. .1— When many devices use the same medium.1. and use software to determine where to forward traffic. An example of a point-to-point connection is a WAN link using a modem. bridges. 5. Outside of the speed limitations of the signal. so an expert administrator and/or patient users prove necessary for the implementation of a server/client network.1.11_1587131749_DAY23. and each port on a switch is its own collision domain or microsegment. use circuits to process the signal.13— Using the client/server model in large networks makes sense because a central server can control host authentication. or the ability to divide switch ports into their own segment. 5. Switches communicate with each other to prevent loops. Switches are able to create virtual circuits between devices that wish to communicate.4—It takes time for a signal to travel across the media. they cannot send data at the same time or a collision will occur. To extend a network with a repeater or hub increases the potential for collisions. Configuration options in the software of a switch allow for the creation of virtual LANs. A switch works like a bridge with many ports. This delay on a network is defined as latency. 8.11—The network interface card (NIC) connects the host to a network.1. file and print access. 8. so each port on a switch is its own collision domain. When the number of hosts exceeds ten. 8. The potential for collisions increases with the increase in hosts. Servers provide a central point of failure. switches cause delay when they wait to learn a destination MAC address.qxd 7/28/06 8:54 AM Page 51 Day 23 51 5. Switches also use content addressable memory (CAM) to quickly store and retrieve MAC table information and application-specific integrated circuits (ASICs) to speed up the process of filtering and forwarding traffic. CCNA 1.2—A bridge initially does not know any MAC addresses on either of its segments. The NIC is considered a Layer 2 device because it carries the MAC. and routers use to identify LAN hosts is burned on the NIC. Each computer acts as a server and client.1. a bridge listens to traffic on both of its ports and builds a table that associates MAC addresses with ports. but a switch has many ports. Point-to-point connections connect only two devices.1 and 8. allowing access to its resources while accessing other peer resources. The best and most adventurous way to learn this advice is through practical experience.1. Once all or many of the devices have communicated over the network. the bridge can determine whether or not to forward traffic between segments. it is wise to implement a server and centralize access to resources for security and organizational purposes. 5.1.1. and back up all vital network data.1.

and routers can filter broadcasts and divide broadcast domains. All hosts must process and respond to this request. Module 5” under 5. In a single collision domain.2. routers. but routers also look at frames and drop any frames that do not have their destination MAC address.2.2—If you can increase collision domains on a network. Class A addresses use the first octet for the network ID and the last three octets to identify the hosts.3—And how does one increase collision domains? Through segmentation with switches and routers. but not so for the demands of today’s serious LAN clan. It is important to follow the 5-4-3-2-1 rule described previously in the section “CCNA 1.4—When a host needs to locate another host. Each time two hosts attempted to communicate. Broadcasts pass across all switches using the broadcast address 0xFFFFFFFFFFFF. then you can improve network per- formance. Routers operate at Layer 3 to forward data using the IP address.2.3—Hosts on a LAN with duplicate IP addresses cannot communicate. 8. Class C addresses use the first three octets to identify the network and the last octet to identify the host. 9. Switches filter traffic by MAC address and keep local traffic local. 8. and other network devices for Layer 2 traffic purposes. This is called an Address Resolution Protocol (ARP) request. it initially broadcasts a request for that host’s MAC address. and Class E addresses are reserved for research.2.6 in order for a network (and network games) to function properly without excessive delay. The 32 ones and zeros in an IP address are divided into octets and represented in dotted decimal notation. Each octet can only be a decimal number between 0 and 255.11_1587131749_DAY23. a collision would occur and all hosts would be required to back off for a set amount of time.4—For the purpose of designing a LAN.2. 8. a Class C addressing scheme often .1—NICs provide a host with a MAC address and the ability to express a unique identity to local switches. If the IP of the destination host is outside the LAN. Each host must have the same network address and a unique host address. so a flat MAC addressing scheme is inferior to a hierarchical scheme using TCP/IP. only one host could communicate at a time.2. For LANs. Imagine a LAN party with 50 hosts connected with hubs.1. you just need general knowledge about address classes and how to implement them.5—To prevent ARP requests from broadcasting to all devices on a network every time a host needs to resolve an address. 9. Class B addresses use the first two octets to identify the network and the last two to identify the hosts. This kind of performance might have been okay for network games in the early ’90s. Switches can filter traffic destined for individual hosts and divide collision domains. LANs are also designed to communicate with other LANs through routers.2. Routers use IP addresses and MAC addresses to filter and direct traffic. the router will respond in order to receive and forward the traffic. you use a router. An ARP request is one example of a Layer 2 broadcast. IP addresses allow hosts to identify themselves by network and local location with a 32-bit address. CCNA 1. Class D addresses are reserved for multicasts.qxd 52 7/28/06 8:54 AM Page 52 31 Days Before Your CCNA Exam 8. Module 9 9. Routers are able to determine whether Layer 2 MAC broadcast traffic is destined for a host outside the LAN by looking at the IP address.

1. and a switch operates at Layer 2. the hosts on the network can use DHCP to obtain an address. such as routers.168.2—Switches operate on the LAN to uniquely identify local machines by MAC address and regulate traffic between these hosts. .11_1587131749_DAY23. If a host tries to communicate with a machine that is not on the LAN.31.168.255. B. It is a good idea to assign static addresses to network devices that other hosts must find on a regular basis.qxd 7/28/06 8:54 AM Page 53 Day 23 53 works well because you do not need more than 255 hosts. An example of how you might address a LAN with 3 hosts using a Class C addressing scheme is ■ Host 1 is 192. or an administrator can statically assign the address.5—Many addresses are reserved for use outside of host identification. servers. or host octet. and C address ranges for private LANs. and network printers.255 ■ Class B: 172. Module 10 10.255.3 ■ Host 3 is 192. this could cause conflicts and render both connected interfaces unable to communicate. 9.4 Notice how the first three network octets remain the same for the entire network and the last octet.6—RFC 1918 states that there are reserved Class A.1—A host on a network can obtain an IP address automatically.2.3.0 to 10. and it is up to the router to use the IP address to find the host.168.255.0 to 192. and the last address (all ones in the host section) is reserved for broadcasts. Once an administrator sets up a DHCP server and identifies a range of available IP addresses.0.168.0. At this point.1.1.168. The private ranges are as follows: ■ Class A: 10.16.3.255.0 to 172. If two interfaces connected to a network are assigned the same IP address.2—Some network administrators of small networks manually provide all hosts with static addresses.2.255 ■ Class C: 192. A router operates mainly at Layer 3.3. CCNA 1. The first address (all zeros in the host section) on a network is reserved for the network.2 ■ Host 2 is 192. 9.5—Dynamic Host Configuration Protocol (DHCP) is the most common way to allow hosts to obtain IP addresses automatically.0. the switch will search for that machine locally and find no matching MAC address. identifies the host.255 9.0. 9. the router steps in and responds for that otherwise unreachable host. 9. The switch forwards the traffic for that host to the router.2. You will likely know when this type of administration does not fit your situation.

A router is most commonly connected to a LAN on its Ethernet or Fast Ethernet interface. Category 5e UTP to connect from these wiring closets to the hosts. At the network and data link layers.1—When you design a LAN. you can use 10/100BaseTX.1. The router connects through a straight-through cable to a hub or switch. ■ Design OSI Layers 1. At the physical layer. Module 5 5. Starting with a router connected to switches in your MDF. From the IDFs.2. If your building exceeds the 100-meter limit for Category 5 UTP to reach all hosts. you can use fiber optics as the backbone vertical cross-connects (VCCs) to IDFs and then distribute connections. data link. 5. and physical layers of the LAN that can act as a road map for implementation.6—The router is the connecting point for a LAN to other LANs or a WAN.3 and 1. Find out quickly who can make decisions and spend money and what they want.1. If your network also includes workgroup servers. 5. create a cut sheet to define location and installation of devices in the facility.1.1.qxd 54 7/28/06 8:54 AM Page 54 31 Days Before Your CCNA Exam CCNA 2. or main distribution facility (MDF). 5. keep the following four goals in mind: ■ Functionality–The LAN has to allow users to accomplish their intended tasks. you can connect the switches to a patch panel and patch cables as horizontal cross-connects (HCCs) to the hosts. and 3 of the LAN—Provide a well-organized chart of the network. Module 1 1.2—If your network includes enterprise servers. you can place them in the intermediate distribution facility (IDF). . ■ Adaptability–The LAN should have the ability to upgrade to accommodate future technologies. ■ Scalability–The LAN should support growth without a need to make any major changes. Use switches to segment collision domains and routers to filter broadcasts. 2. This structure can follow the TIA/EIA-568-A standards including your wiring scheme.11_1587131749_DAY23.4—To design the OSI Layer 1 scheme for a simple LAN. Also document the financial and managerial structure of the network. the use of fiber optics and Fast Ethernet is most common. include the logical topology and an addressing scheme to define the flow of the network. ■ Manageability–You should be able monitor and maintain the network in order to keep a stable environment. ■ Analyze the data you have gathered—Use data from the previous action to estimate costs and a timeline to implement the project. CCNA 3. place them in the main wiring closet.1.3—Actions that you can perform while designing a LAN are as follows: ■ Gather LAN requirements and expectations—Determine the skill level and attitude of the users as well as the demands put on the network by host hardware and software.

you need to switch gears and focus on the Cisco Three-Layer Hierarchical Model. logical structure. and Lightstream 1010 fit the bill. but you need a router to communicate between VLANs. No access list implementation or packet manipulation occurs at the core layer. IGX 8400. and 5000 series switches at the access layer. 3550.2. 5. Second Edition. To microsegment collision domains. . explain. 2820. and aggregation in the wiring closet at the distribution layer protect the core layer from handling these functions. Once you have determined how many ports you will need for all hosts and connections to the LAN. Routers commonly forward data based on IP addressing.1. HCCs are direct to hosts and should balance with a faster VCC between wiring closets. 5000. and the Catalyst 6500. 5.2. Summary Networking devices.2. and access layers. distribution. 5.2—Access layer switches operate at Layer 2 of the OSI model.1.qxd 7/28/06 8:54 AM Page 55 Day 23 55 5. you can place appropriate switches in the MDF and IDFs. provide microsegmentation. Switch ports have only two hosts per collision domain with a source and destination host. or document a LAN. VLANs. which provide an outline for the types of devices and connectivity necessary in a large network. Collision domain microsegmentation and MAC address filtering also occur at the access layer. 2950. you should use switches. The core layer serves as the backbone reserved for high-speed transmission. if you have time. You can divide Layer 2 switches into virtual LANs (VLANs) to separate networks at Layer 3. connect LANs. 3560. You need a beefy OSI Layer 2 or 3 switch to handle the demands of the core layer.4—The distribution layer handles packets and OSI Layer 3 policies so that the core layer remains fast and efficient. You could use Catalyst 1900. ACLs.5—As the backbone of the network. and design layers surface any time you design. and 6000 families at the distribution layer. and can be separated into VLANs.5—Your OSI Layer 2 design will focus on how the LAN will forward frames. The use of hubs instead of switches increases the size of collision domains to all hosts connected and affects bandwidth. 8500.3 and 5. Routers can also act as firewalls and provide a WAN connection. the core layer is designed to move packets as quickly as possible. You could use Catalyst 2926G. 5.6—Layer 3 LAN design centers around the placement and configuration of routers on the LAN. This model consists of the core.11_1587131749_DAY23. The distribution layer divides the core layer from the access layer with policy.2. Distribution layer devices include OSI Layer 2 and Layer 3 switches. Redundant paths implemented with Ethernet or ATM characterize the core layer. and divide broadcast domains between the LANs. Browse through pages 13–66 of the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study.1—At this point. exam #640-801).2. These concepts also show up often on the CCNA. 4000. The access layer connects users and remote sites to the network. 5.

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Module 1 1.7 Binary 11000000. “Evaluate the TCP/IP Communication Process and Its Associated Protocols. and Table 22-2 shows an example of an IP address in both dotted decimal and 32-bit binary. Table 22-1 shows the powers of 2 for an 8-bit binary number. If you are not sure how this conversion works. refer to Day 27.168. Module 9 9.1–9. C.5–1. CCNA 1. D. It is important to chop away at subnets and use advanced addressing to design a more efficient and secure network. public. and E IP addresses.7—You cannot leave out binary in the quest to understand IP addressing.2.8—On Day 27 you covered default address classes and reserved. Table 22-1 One Octet of an IP Address Bits and Powers of 2 1 1 1 1 1 128 64 32 16 8 Table 22-2 1 4 Decimal Equivalent 1 1 2 1 128+64+32+16+8+4+2+1 = 255 Binary-to-Decimal Conversion for an IP Address Numbering System IP Address Decimal 192. The main points necessary for today are outlined in Tables 22-3 through 22-5.2. Table 223 shows Class A.00000001.qxd 7/28/06 8:54 AM Page 57 Day 22 Design an IP Addressing Scheme to Meet Design Requirements Day 27. Notice that the IP address is made up of four sets of 8 bits (octets).12_1587131749_DAY22. and today you learn the topics that allow you to be flexible and creative with IP addressing design.2.” discussed basic IP addressing. .1.00000111 CCNA 1. and private IP addresses.10101000.2. B. You will cover a quick review of the topics from Modules 1 and 9 from CCNA 1 and then learn new concepts in Module 10 from CCNA 1 and Module 1 from both CCNA 3 and CCNA 4.

the subnet mask will reflect the bits that you have borrowed.1 to 192.255 192.H 254 24 Class D 1110 224–239 H. B. D. which are defined in the IETF RFC 1918. and add security with access lists.31.255. the subnet mask in both decimal and slash format.1.H.H.0 is reserved for the loopback. and E IP Addresses Class Binary Start 1st Octet Range Network (N) and host (H) Octets Number of Hosts Bits in Network Address Class A* 0 1–126 N. and you will have more networks but fewer hosts for each network.3—A default Class C network has a subnet mask of 255.0 to 10. If you borrow bits from the host portion. B.0 192. and C default networks into smaller networks by identifying individual bits in the host portion as network bits.3.N.1. . You have the entire last octet to address hosts (minus the network and broadcast address).2—You can break up the Class A.254 Table 22-5 lists the Class A.0 to 192.H Multicast 28 Class E 1111 240–255 RESEARCH RESEARCH RESEARCH * The Class A address 127. Class B. Table 22-5 RFC 1918 Private Network Addresses Class Address Range Class A 10.168.1. and the amount of networks and hosts.0. divide broadcast domains on your network. Table 22-4 shows an example of the addresses reserved on a network to represent the broadcast and the entire network.0.168.255 CCNA 1. Table 22-4 Reserved Network and Broadcast Address Example Network Default Class C Binary Host All 0s Network Address Binary Host All 1s Broadcast Address Useable Hosts 192.535 16 Class C 110 192–223 N.0.255.3.255.255. Table 22-6 provides the bits borrowed from the host portion.255.1.H.3.16.255 Class C 192.168.168.0. which allows you to efficiently use IP addresses.qxd 58 7/28/06 8:54 AM Page 58 31 Days Before Your CCNA Exam Table 22-3 Class A.0. C.N. Module 10 10.12_1587131749_DAY22.H.0 to 172.1 and 10.255 Class B 172. and to subnet the last octet of a default Class C. and Class C private address ranges.H About 16 million 8 Class B 10 128–191 N.168.1.0.H 65. The term for this practice is subnetting.255.N.H.168.0.0 192. 10.168.

255.62 192.1–.168.4—To continue with the example of 2 bits borrowed. As an example. Table 22-7 Subnetworks for 192.1.255 Remember that the subnetwork ID cannot be assigned to an interface. Use of the first and last subnets is discussed later today in the section “CCNA 3.168.63 1 192.3.168. 10.5—You need to rely heavily on the use of binary representation and the 2^n–2 formula (unless you are using the zeros and ones subnets) when subnetting a Class A or Class B network.191 3 192.1. Module 1.192 Mask) Subnetwork Number Subnetwork ID Host Range Broadcast ID 0 192. .1.127 2 192. you can place those remaining bits in the formula 2^n–2 and you will find that you have 62 hosts available per network.0 with 2 Bits Borrowed (255.168.168. you can also determine the interval for the subnetworks using the mask.1.qxd 7/28/06 8:54 AM Page 59 Day 22 Table 22-6 59 Bits Borrowed and Corresponding Mask for a Class C Network Bits Borrowed 1 2 3 4 5 6 7 8 Mask 128 192 224 240 248 252 254 255 Slash format /25 /26 /27 /28 /29 /30 /31 /32 Total subnets 2* 4 8 16 32 64 N/A N/A Useable subnets* 0* 2* 6* 14* 30* 62* N/A N/A Total hosts 128* 64 32 16 8 4 N/A N/A Usable hosts 126* 62 30 14 6 2 N/A N/A *Refers to CCNA 3.64 . This gives you an interval of 64. RFC 1878 (Dec.193–. The host range would fall between the network and broadcast addresses. If you look at the number of zeros in the mask 11000000.” 10.12_1587131749_DAY22.1. 1995) started the use of all zeros and all ones for subnets.168. In this case.0 .63–. Module 1.1. Table 22-7 provides an example of the networks and host ranges available for a default Class C network with 2 bits borrowed. You can determine all of the information in Table 22-6 by using the binary representation and the powers of 2. To find the amount of networks.192 .255. the /26 network means that there are 26 bits total for the network portion.190 192.168. (Remember that a default Class C uses 24 bits. your result is two networks available. Using this interval. In this case. or 192.168. Make sure that you understand when you can use the all zeros and all ones subnets. you can use host bits available and apply the formula 2^n without subtracting 2. so the last octet of the mask is the decimal representation of 11000000. The /25 subnet is now usable as well as the number of subnets listed in the total subnets row.1. you can insert the number of bits borrowed into the formula 2^n–2 (unless you are using the all ones and all zeros subnets).168.254 192.129–.1. you can start with the zero subnet and then add 64 to identify your networks.128 .126 192.1.3.) You have borrowed 2 bits from the last octet and changed them from host bits (0) to network bits (1).

4.11111110. Table 22-9 Using the AND Operator to Determine a Network Address AND Operator IP Address and Subnet Mask to Network Address 0 AND 0 = 0 IP address 172.12_1587131749_DAY22. Enhanced Interior Gateway Routing Protocol (EIGRP).254.0.11111111.qxd 60 7/28/06 8:54 AM Page 60 31 Days Before Your CCNA Exam It is technically the same as subnetting a Class C. Table 22-8 provides a subnetted Class B network as an example with the first four subnetworks. and Routing Information Protocol version 2 (RIPv2) support VLSM.0 CCNA 3.16. you can use the first and last subnets in conjunc- tion with VLSM. Using VLSMs.5.0.16.0 .1—You can efficiently use IP addresses by implementing variable-length subnet masks (VLSMs). Integrated Intermediate System-to-Intermediate System (Intermediate IS-IS).00000000 1 AND 1 = 1 Result Mask 255.00100110 1 AND 0 = 0 Subnet mask 11111111.7. but you may need to deal with higher powers of 2.3.255.1–7.1–1.255.0 10101100.0 .2.0 with 7 Bits Borrowed (255.00010000.4.1.16.1.00000000 Network address 172.1.2.16. you can choose the subnet mask that best suits the number of hosts for each section of the network.1–5.0.00000010.0 .2.16.16.00010000.3 and 1.16. a router uses the AND operator to determine the network and host portion of an address.255 10.0.4—Consider the three subnetworks in use in Table 22-10 applied to a network with a serial point-to-point connection between two routers with 250 host LANs connected to each router.6.16.) Table 22-8 Subnetworks for 172.2.1.0 .3.2—As noted by the asterisks in Table 22-6.254 172.255 1 172. 1. so you do not need to subtract 2 to determine usable subnets.16. Module 1 1.16. routers can use subnet zero by default. An example is to divide a Class C /24 mask to use the /30 mask for a point-to-point connection and then a /28 mask for a network with ten hosts.6—As mentioned on Day 27. (There would be 128 total. 1.00000010. After Cisco IOS Release 12.16.254 172.38 0 AND 1 = 0 IP address 10101100. The no ip subnet-zero command enables use of these subnets in Cisco IOS software versions before Cisco IOS Release 12.255 3 172.1. With subnetworks it is important that a router know the subnet mask for a network in order to forward the packet to the correct subnetwork.254.1–3. Table 22-9 reviews the ANDing process with an address from subnetwork 1 in Table 22-8.254 172.0.255 2 172.254 172. Static routes and only certain routing protocols such as Open Shortest Path First (OSPF). .0 Mask) Subnetwork Number Subnetwork ID Host Range Broadcast ID 0 172.6.

0 /24 1.0 /24 2.0.0.16. ■ The router will send the packet to the Internet server’s outside global address of 128.0 with 8 Bits Borrowed (255.2.2. .254 172.1.255 Notice that the point-to-point link is flagrantly using 254 hosts when it only needs 2.0.1.0 /24 1.0.16. You can free up most of those hosts by implementing VLSM and using the networks outlined in Table 22-11.16.16.8.254 172. or summarization.254 172.1.4 /30 0.0.6 172.255 2 172. keeps routing tables small between networks.80 as the source address for the packet on the Internet.16.2.255.16. you can represent an internal IP address as an external (real) IP address. You can check host ranges for duplicates.5 with its inside global address of 179.0.0.16.16. 1. This type of route aggregation.16.16.0 space by using the /30 mask.16.80. your router has an interface on the Internet with the address 179.254 172.1–2.1–1.1.16. VLSM and classless interdomain routing (CIDR) allow for more efficient use of IP address space and routing tables.16. If you have an internal PC hostA with an address of 10.5.16.0.0.255 2 172.16.8. a router can represent the group of subnets as one large subnet to other routers.7 1 172. ■ The router will replace the source address 10.254 172.2.0 with VLSMs Subnetwork Number Subnetwork ID Mask Host Range Broadcast ID 0 172.23.0 /24 0. Table 22-11 Subnetworks for 172.16.5–0. Make sure that you do not later use a large subnetwork (an example would be 172.3—If you have designed a network using nonroutable private addresses (specified earlier in Table 22-5).2.2.1.255 This configuration leaves many available subnetworks in the 172.0. CCNA 4.1. Using only NAT.1–2.0 /24 for Table 22-11) that includes a small subnetwork you are already using.255. you can still connect these internally addressed hosts to the Internet using network address translation (NAT) and port address translation (PAT).0 /24 2. the following could happen with NAT: ■ HostA will send its packet with the inside local address of 10.0.0.23.12_1587131749_DAY22.1–1.1–0.2.5.qxd 7/28/06 8:54 AM Page 61 Day 22 Table 22-10 61 Subnetworks for 172.255 1 172. and hostA attempts to communicate with an Internet server with the address 128.5—If you use VLSM and keep your subnets sequential or grouped together.9. but for complicated networks it might help to find a VLSM chart on the Internet and use it to cross out used subnetworks.1–1. Remember when you are using VLSM that your host ranges cannot overlap.0.0. Module 1 1.1.0 Mask) Subnetwork Number Subnetwork ID Mask Host Range Broadcast ID 0 172.2.

VLSM. Practice and research different methods and examples to help solidify your abilities with subnetting and VLSM. Second Edition. Overloading.0. RFC 1918. CIDR. or assigning multiple private addresses to one Internet IP address. If you have the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study. Summary Now you should be able to design a network that incorporates NAT. PAT. Your Notes . PAT uses source port addressing to represent multiple private addresses with one Internet IP address.0.5. This knowledge not only puts your best foot forward at a job interview.12_1587131749_DAY22. and good ol’ IP. A pool of Internet addresses can be dynamically mapped to private addresses. NAT can only map one Internet IP address to one private IP address. look over pages 141–146 and 475–480. exam #640-801). but also helps you to understand and troubleshoot a number of OSI Layer 3 issues. it will look in its NAT table and see an entry that maps the packet from the server back to hostA’s inside local address of 10. but the ratio is still one to one.qxd 62 ■ 7/28/06 8:54 AM Page 62 31 Days Before Your CCNA Exam When the router receives a reply from the Internet server. proves possible with NAT and PAT together.

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Day 21
Select an Appropriate Routing
Protocol Based on User
Requirements
CCNA objectives for today and Day 28, “Evaluate the Characteristics of Routing Protocols,” complement each other. Today you focus on comparing routing protocol features to perfect your ability
to pick the proper protocol. If you have completed Day 28 and can characterize routing protocols,
you should not have much trouble understanding the concepts behind the features. Today we first
outline the function of a routing protocol with information from CCNA 1 Module 10. You will
then review only the information that compares routing protocols from Module 6 of CCNA 2 and
Modules 1, 2, and 3 from CCNA 3.

CCNA 1, Module 10
10.1.1—Routing protocols allow routers to learn about available networks. Routed protocols provide addresses for hosts to communicate over a network. As a routed protocol, IP uses a subnet
mask to identify the network. Day 27 and Day 22 explained how a subnet mask allows a router to
identify a group of IP addresses as a network.
10.2.1—Routing occurs at OSI Layer 3. Routers look only at an individual address in order to

apply a netmask and then find the path to the network. Routers see networks, not individual
addresses. The individual IP address becomes necessary only to determine the final destination of
the packet. Other OSI Layer 3 routed protocols are Internetwork Packet Exchange (IPX) and
AppleTalk. NetBEUI is the most common nonroutable protocol.
10.2.2 and 10.2.3—As a switched LAN grows, it becomes necessary to segment the LAN with
routers. Routing and switching processes both forward data based on addressing, but switching
occurs at Layer 2 using the MAC address. The MAC address is unique to the LAN and allows the
switch to forward frames and maintain a flat table of MAC addresses without any specific organization. The router maintains a routing table of connected networks and uses the Layer 3 addressing
scheme to forward packets outside of the LAN and to other LANs. The hierarchical nature of
Layer 3 addresses allows the router to group and organize network knowledge. Additional examples of these Layer 3 routed protocols are Banyan VINES and Xerox Network Systems (XNS).
10.2.5–10.2.9—Day 28 presents most remaining information in Module 10 using summaries
from CCNA 2 Module 7. CCNA 1 Module 10 does add that routers determine network paths using
the following information from a routing table:

Protocol Type—The Layer 3 routed protocol

Next-hop association—The directly connected network or a network that the router has
learned about through a routing protocol

Routing metric —Used to determine the most efficient path

Outbound interfaces—Which interface to forward the packet for the specified route

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CCNA 2, Module 6
6.2.1–6.3.4—Table 21-1 and Table 21-2 review points about types of routing protocols covered in

Day 28 from CCNA 2 Module 6 with the addition of administrative distances for each routing
protocol.
Table 21-1 compares distance vector and link-state protocols.
Table 21-1

Distance Vector and Link-State Protocols

Distance Vector

Link-State

Routers send periodic updates of the
entire routing table to neighbors.

Routers send link-state advertisements (LSAs) to update other
routers only when there is a topology change.

Routers see only neighboring routers.

Routers use the LSAs to build a full loop-free topology of the
network, but this requires more memory than a distance vector
protocol.

Routers use a metric to determine the
cost path for a route and build a routing
table.

Routers use the Shortest Path First (SPF) algorithm and LSAs to
build a shortest path tree as well as a routing table.

Table 21-2 describes specific distance vector, link-state, and hybrid protocols.
Table 21-2

Routing Protocols

Protocol Name

AD

Type

Description

Routing Information
Protocol (RIP)

120

Interior distance vector

Broadcasts updates every 30 seconds and uses hop count as the metric with a maximum of 16

Interior Gateway Routing
Protocol (IGRP)

100

Interior
distance vector

Cisco proprietary protocol that
broadcasts updates every 90 seconds
and uses bandwidth, load, reliability,
and delay as a metric

Open Shortest Path First (OSPF)

110

Interior link-state

Nonproprietary protocol that
updates only when there is a change
in topology. OSPF uses cost as a
metric

Enhanced Interior Gateway
Routing Protocol (EIGRP)

90

Interior hybrid

Cisco proprietary protocol that uses
both link-state and distance vector
features and multicasts updates on
224.0.0.10. EIGRP uses the same
metrics as IGRP

Border Gateway Protocol (BGP)

20

Exterior distance vector

Used to route between autonomous
systems

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CCNA 3, Module 1
1.2.1–1.2.3—Table 21-3 compares RIPv1 and RIPv2.
Table 21-3

RIPv1 vs. RIPv2

RIPv1

RIPv2

Simple configuration.

Simple configuration.

Does not send subnet mask information in
the routing update. All subnets must have
the same subnet mask.

Sends subnet mask information with updates. Supports
VLSM and CIDR.

No authentication.

Supports MD5 authentication.

Broadcasts updates over 255.255.255.255.

Sends updates as multicasts over 224.0.0.9.

CCNA 3, Module 2
2.1.1–2.1.6—The following points are additional features of a link-state protocol:

Link-state protocols send hellos periodically to obtain information about neighboring routers.

When a network changes, a router will flood LSAs on a specific multicast address across the
specified network area.

LSAs allow the router to create a topological database of the network, use the Dijkstra algorithm to determine the shortest path for each network, build the shortest path tree, and use the
tree to build the routing table.

Flooding LSAs across a network can affect overall bandwidth on a network and cause each
router to recalculate a full topological database.

A network using a link-state protocol must be broken up into small enough areas to maintain
network efficiency and use routers with sufficient memory and processing power.

2.2.1–2.2.7 —OSPF includes these features:

OSPF is a nonproprietary link-state protocol that allows you to control the flow of updates
with areas.

OSPF allows more than 15 maximum hops, and large networks can be divided into areas.

OSPF areas communicate with a backbone area to reduce routing protocol traffic and routing
table size.

OSPF-enabled routers are true to their link-state definition in that they maintain a full loopfree topological database of the network.

Each OSPF-enabled router maintains a unique adjacency database that tracks only neighbor
routers.

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OSPF-enabled routers elect a designated router (DR) and backup designated router (BDR) as
central points for routing updates.

VLSM support, a bandwidth-based metric, a loop-free SPF tree, and rapid convergence
through LSAs are key features of OSPF.

OSPF routers that are connected on broadcast multiaccess networks such as fiber or Ethernet
or nonbroadcast multiaccess networks such as Frame Relay elect a single router to handle
updates called the DR. To avoid a single point of failure, they also elect a BDR.

OSPF hello packets typical to link-state protocols go out over the multicast address 224.0.0.5.
If the connection is broadcast or point-to-point, the hellos go out every 10 seconds; and if the
connection is nonbroadcast multiaccess (NMBA), the packets go out every 30 seconds.

CCNA 3, Module 3
3.1.1 and 3.1.2—Each of the following points identifies an EIGRP feature:

EIGRP and IGRP routing protocols can function seamlessly together on a network.

EIGRP also supports VLSM where IGRP does not. A router running only IGRP will see
EIGRP routes as IGRP routes.

As an advanced distance vector routing protocol, EIGRP uses functions from both link-state
and distance vector protocols.

Like OSPF, EIGRP collects multiple databases of network information to build a routing
table.

EIGRP uses a neighboring table in the same way that OSPF uses an adjacency database to
maintain information on adjacent routers.

Unlike OSPF, EIGRP uses a distance vector diffusing update algorithm (DUAL) to recalculate a topology.

EIGRP maintains a topology table that contains routes learned from all configured network
protocols.

The neighboring and topology table allow EIGRP to use DUAL to identify the best route, or
the successor route, and enter it into the routing table. Backup routes, or feasible successor
routes, are kept only in the topology table.

In the topology table, EIGRP can also tag routes as internal or external. Internal routes are
from inside the EIGRP AS, and external routes come from other routing protocols and outside
the EIGRP AS.

3.1.3 and 3.1.4—Advanced features of EIGRP that set it apart from other distance vector routing

protocols include:

Rapid convergence—EIGRP uses the DUAL finite-state machine (FSM) to develop a full
loop-free topology of the network allowing all routers to converge at the same time.

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Efficient use of bandwidth—EIGRP, like OSPF, sends out partial updates and hello packets,
but these packets go only to routers that need the information. EIGRP also develops neighboring relationships with other routers.

Support for VLSM and CIDR—EIGRP sends the subnet mask information allowing the
network to be divided beyond default subnet masks.

Multiple network layer support—Rather than rely on TCP/IP to send and receive updates,
EIGRP uses Reliable Transport Protocol (RTP) as its own proprietary means of sending
updates.

Independence from routed protocols—EIGRP supports IP, IPX, and AppleTalk. EIGRP has
a modular design that uses protocol-dependant modules (PDMs) to support other routing protocols, so changes to reflect revisions in the other protocols have to be made only to the PDM
and not EIGRP.

Summary
Once you are comfortable with the key features and comparisons of each routing protocol, you
will be able to factor network size, growth potential, Layer 3 addressing, and compatibility into
your selection of the proper routing protocol. If you have read through pages 388–450 of the
CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study, exam #640-801), Second Edition,
it should be very easy to RIP (pun intended) through them again. You can focus on the commands
on a later day. Remember that you have both Day 28 and the curriculum as a reference for today.

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■ Intranet VPNs—Provide a connection for regional and remote offices for employees.1. Virtual private network (VPN) Provides a private network that exists inside of a public network. . Storage-area network (SAN) Provides high-performance. Table 20-1 explains the advanced concepts behind networks that are more than just a LAN. ■ Extranet VPNs—Link business partners to an internal network.1. virtual private networks (VPNs). or optical services.qxd 7/28/06 8:55 AM Page 69 Day 20 Design a Simple Internetwork Using Cisco Technology When you interconnect LANs.1. This intranet provides employees using the LAN browser access to information and applications on a local server. scalable storage for servers over a separate network from the client/server network. Module 2 2. 2. You will cover specific WAN service technologies on Day 18. you will find storage-area networks (SANs). and metropolitan-area networks (MANs). “Choose WAN Services to Meet Customer Requirements. and Modules 1 and 2 from CCNA 4 teach the concepts you need to understand in order to define and design internetworks. you can configure a local intranet. These partners do not have to be employees of the business. If your LAN is connected to a WAN.14_1587131749_DAY20.7–2. e-mail.11—Three main types of VPNs exist: ■ Access VPNs—Allow a client from a home or small office to connect to the main site. Module 8 from CCNA 3. Table 20-1 Network Types Network Type Function Wide-area network (WAN) Connects LANs using serial transmission over a large geographic area to provide remote resources. Modules 2 and 8 from CCNA 1.10—A LAN provides connectivity for local devices in the same room or building.12—On a LAN.1. Metropolitan-area network (MAN) Connects LANs in a metropolitan area using private lines. and the Internet. Once you step outside of the LAN. a wireless bridge.” CCNA 1. fault-tolerant. 2. you can provide extranet access to this server for Internet users with the proper authentication. Clients connect through a secure tunnel to the VPN router at the destination. you create an internetwork.

Millions of cable Internet and digital subscriber line (DSL) subscribers have routers that can implement NAT and PAT.3–8.1. Module 8 8. CCNA 3.” your computer needs a registered IP address to communicate on the Internet. 1. it performs the following actions: ■ The switch maintains a separate MAC address table for each VLAN. then you have one large broadcast domain. Switches capable of VLANs allow you to use software to logically divide the network into separate broadcast domains. port-centric VLAN. ■ The switch is capable of connecting to other switches and sharing VLAN information. DHCP provides a way for any . Module 1 1.1. and each VLAN is its own broadcast domain. This dynamic membership VLAN allows users to move around and remain in the same VLAN. Imagine that these 24 employees belong to three groups and you want to divide the LAN into three broadcast domains.2—If you have one switch with 24 connected employees.1.7—The term segment holds many meanings in networking.1 and 1. If you do not want users to move around.1. but you can use an RFC 1918 private address range with a LAN and implement network address translation (NAT) and port address translation (PAT) on your router to connect your entire LAN to the Internet with just one outside IP address. “Configure a Switch with VLANs and Interswitch Communication. ■ The switch uses only the MAC address table from a specific VLAN to learn addresses and forward frames for that VLAN. ■ The Layer 2 switch does not allow communication across VLANs without a Layer 3 router.2.qxd 70 7/28/06 8:55 AM Page 70 31 Days Before Your CCNA Exam CCNA 1. you could buy two more switches. or you could use the capabilities of the switch to create VLANs.2—If you design a LAN connected to the Internet using NAT and PAT.1. you can create a static VLAN. A frame forwarded from VLAN1 on switchA will be seen by VLAN1 on switchB only if the switches are trunked. To divide this network. “Design an IP Addressing Scheme to Meet Design Requirements. Module 8 from CCNA 3 discusses how to segment a network logically with switches.3—As discussed on Day 22. To create a static.5—VLANs give you complete control over the logical topology of your network despite the physical arrangement of your switches. Module 8 8.1.”) 8.2. CCNA 4. it would be a great idea to add Dynamic Host Configuration Protocol (DHCP). you can map each port on a switch to a VLAN regardless of who connects to that port. Segments are the OSI Layer 4 protocol data unit (PDU).1–1.1 and 8.14_1587131749_DAY20. You can use software to control VLAN membership by MAC address or logical address. A segment can represent a physical portion of a network divided by repeaters or a logical portion of a network divided by routers. (Expect more about trunking on Day 14. When you divide a switch into VLANs.2.

1 and 2.2. Module 2 2. consider the following factors: ■ You will likely purchase your WAN connections from a communications provider for cost and legal reasons. If the client detects that an IP address is in use on the network. DNS server. and the client can start using the IP address. by default. it will send a DHCPRELEASE. BOOTP requires you to configure a static map of IP addresses for each client you add to the network.2. it will send a DHCPDECLINE and start another request. If the client receives DHCPOFFERs from more than one DHCP server.qxd 7/28/06 8:55 AM Page 71 Day 20 71 host that you connect to the LAN to automatically obtain an IP address from your router using the transport layer User Datagram Protocol (UDP) ports 67 and 68.2—When you design the WAN portion of an internetwork.3. it will typically accept the first offer it receives. DHCP can lease an IP address to a client from a pool of addresses and provide other configuration information such as a domain name. a client first sends a DHCPDISCOVER broadcast. CCNA 4. DHCP replaced the Bootstrap Protocol (BOOTP) as a more advanced means of allocating an IP address.4—To obtain an IP address using DHCP. to check for used IP addresses before sending a DHCPOFFER. and lease time. A DHCP server will either respond to the broadcast with a unicast DHCPOFFER or forward the request to another DHCP server.14_1587131749_DAY20. Configuration parameters you can set for the host in DHCP include the following: ■ Subnet mask ■ Gateway router ■ Domain name ■ Domain name server ■ Windows Internet naming WINS server 1.3—DHCP offers three types of IP address allocation: ■ Automatic allocation of a permanent address ■ Manual allocation of an address configured by the administrator ■ Dynamic allocation of an address leased for a limited period of time You can configure the DHCP pool to include any range of addresses from one subnet. ■ WANs function at the lower three layers of the OSI model but focus on Layers 1 and 2. The DHCP server will then send a DHCPACK unicast. WAN connections are slower than LAN connections but may need to support voice and video as well as data. ■ You must balance the cost of WAN connections with the speed necessary for your WAN to function. A Cisco DCHP server will ping its address pool twice. .3. The client notifies the network that it has accepted a request by broadcasting a DHCPREQUEST with the accepted configuration. The DHCPOFFER can include an IP address. 1. When the client is done with the IP address.

Step 2 Analyze traffic. In your notes. Step 3 Plan a topology. Step 6 Evaluate cost. Second Edition. Summary At the point that you plan to segment LANs and connect them with WAN technologies. you begin the process to create an entire internetwork. it might help to diagram the DHCP process and key features of VLANs. Your Notes . consider the following steps: Step 1 Locate LANS. you might like to quickly look at pages 59–68 and 350–354 in the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study. Step 5 Choose technology. Step 4 Plan bandwidth. Before turning the page. exam #640-801).14_1587131749_DAY20. you will be ready to move on to the even more exciting sections about configuration and troubleshooting.qxd 72 7/28/06 8:55 AM Page 72 31 Days Before Your CCNA Exam To design a WAN. When you study the specific WAN technologies on Day 18.

168.0. Module 11 11. there is an implicit deny.15_1587131749_DAY19. To create the ACL.0.3—Remember the following guidelines for an ACL from Day 25.1. 0. CCNA 2. .0 can also be represented by the term any or host in an ACL. you switch to interface mode and use the command ip access-group.0 to 192. Module 11.1.0. ■ When an IP ACL rejects a packet. To control traffic with an ACL.1. ■ You can apply one ACL per protocol per direction per interface. which is covered in CCNA 2.0. A wildcard mask uses binary ANDing to show what part of an IP address should be matched. 11.0. you use the wildcard mask to specify the range. you first create the ACL and then apply the ACL in a direction to a port. The wildcard mask 0. “Implement an Access List.” When you identify a group of IP addresses in an ACL.255 tells the router that the ACL must match the range 192. ■ Place standard ACLs closest to the destination.1. Both commands have syntax and parameters that will be covered with examples on Day 10. “Evaluate Rules for Packet Control”: ■ The way to revise an ACL is to delete and re-create it unless it is a named ACL. ■ A router stops checking ACL statements after the first match. ■ At the end of every ACL.7 with the wildcard mask 0.1.0 states that the ACL should match the entire host. the IP address 192.0.4—Do not look for a relationship between wildcard masks and subnet masks. Short days like today provide a great opportunity to take a Cisco Academy online practice CCNA test or get a head start on the next day.qxd 7/28/06 8:55 AM Page 73 Day 19 Develop an Access List to Meet User Specifications Today you review the guidelines for creating an access control list (ACL). you use the command access-list in global configuration mode.168. wildcard masks serve an entirely different function from subnet masks. As explained on Day 25. ■ Do not work with an access list that is applied.1. ■ Place extended ACLs closest to the source.1–11. To apply the ACL. ■ A router checks ACL statements in the order in which you create them.255. ■ An ACL should filter specific addresses first and then groups of addresses. ■ Outbound ACLs do not affect traffic originating from the router.168. it sends an ICMP implicit deny.

15_1587131749_DAY19.2. 11. If you have a copy of CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study. 11.5—ACLs allow you to control traffic. but more importantly they also allow you to protect users. On Day 3.2. because an extended ACL is able to look at the destination address in a packet. Extended ACLs use the number range 100 to 199.qxd 74 7/28/06 8:55 AM Page 74 31 Days Before Your CCNA Exam 11. “Troubleshoot an Access List. You should apply the same restrictions to all VTY lines on a router and use only numbered ACLs. look through pages 456–468.1–11.2.” you will cover the commands and output associated with ACL verification. ■ Named ACL—Named ACLs do not use a range of numbers because the name is the identifier. 11. you can verify that it is present by looking at the configuration or by looking at the specific interface where you applied the ACL. Border routers configured with ACLs can act as firewalls and protect internal LANs from attacks that originate from outside your network.3—Remember the following key points about each type of ACL: ■ Standard ACL—This type of ACL uses the number range 1 to 99 and checks only the source address.4—You should put an extended ACL as close to the source of the traffic you are filtering as possible.6—A router has five virtual ports called VTY lines that you can control with an ACL. . destination. ■ Extended ACL—With an extended ACL. Named ACLs can be configured as standard or extended ACLs. exam #640-801). and port. Summary First you determine the traffic that you want to permit and deny. Second Edition.1. and lastly you apply the ACL to an interface. The implementation guidelines outlined today prepare you for ACL configuration and troubleshooting on days 10 and 3. and then you create the rules in the list. protocol.5—After you have created and applied an ACL. you can check the source.2.2. 11. or who is sending the packet. You should put a standard ACL as close to the destination of the traffic you are filtering as possible because a standard ACL looks only at the source address of a packet.

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Table 18-1 WAN Physical Connections Connection Physical Type Connectors Cabling Serial 60-pin or smart serial The router connects to a channel service unit/data service unit (CSU/DSU) with a data terminal equipment (DTE) serial cable. then connect the DB-9 end to the serial port on a computer.6—WAN physical connections include serial.048 Mbps for an E1. Integrated Service Digital Network (ISDN).2. A BRI U interface includes the NT1. Table 18-1 provides a brief description of how to cable WAN services. CCNA 1.” you evaluated the key characteristics of WANs.10—WANs connect LANs over a large geographically separated area using a modem on a plain old telephone service (POTS) line.qxd 7/28/06 8:55 AM Page 77 Day 18 Choose WAN Services to Meet Customer Requirements On Day 24. the router will connect with a BRI S/T interface. . You connect ISDN with an RJ-45 connector.7 and 2. CCNA 1. Console RJ-45 to DB-9 Use a rollover cable and connect to the RJ-45 console port on the router. DSL RJ-11 Connect a DSL router using a standard RJ-11 phone connector and phone line.54 Mbps for a T1 and 2. T3. Now you can view these characteristics with the intent to determine which type of WAN works best for a given situation. Point-to-Point Protocol (PPP).16_1587131749_DAY18. 3. Modules 2 and 5 from CCNA 1. Cisco High-Level Data Link Control (HDLC).1. or E3.2. 4. RJ-45. Module 5 5. and Frame Relay use serial connections and provide speeds ranging from 2400 bps to 1. Cable F-connector Connect a cable modem with a standard coaxial cable and F-connector. and Modules 2.1. RJ-11. Module 2 2. WANs often provide access over serial interfaces at lower speeds than a LAN. ISDN BRI S/T BRI U If a network termination 1 (NT1) device is needed. ISDN basic rate interface (BRI) provides two 64 kbps bearer (B) channels and one 16 kbps delta (D) channel. A LAN can be extended through a public WAN using a virtual private network (VPN).1–5. digital subscriber line (DSL). and 5 from CCNA 4 provide the content necessary to understand and choose a WAN service. Synchronous Optical Network (SONET). Module 1 from CCNA 2. T1. A VPN provides a private network that exists inside of a public network. and F-connectors. E1. Frame Relay. “Evaluate Key Characteristics of WANs. Clients connect through a secure tunnel to the VPN router at the destination.

1.1. Table 18-2 WAN Physical Layer Standards Standard Speed EIA/TIA-232 64 kbps EIA/TIA-449/530 Up to 2 Mbps EIA/TIA-612/613 HSSI up to 52 Mbps V. A modem can also serve this purpose by modulating and then demodulating the signal in order to pass digital information over an analog line on the public switched telephone network (PSTN). 2.1. CPU. modems.qxd 78 7/28/06 8:55 AM Page 78 31 Days Before Your CCNA Exam CCNA 2. you will almost always coordinate with a communication service provider such as a local phone company and use routers. When you design a WAN.2—If you have selected a WAN service that uses a communication service provider. ■ Supervisory frame—This frame controls data frame flow and can request retransmission if an error occurs. Module 2 2. the phone company provides you a port as the demarcation point.21 Synchronous digital up to 64 kbps Table 18-3 WAN Data Link Layer Protocols Type Protocol Point-to-point Cisco HDLC. In your building.4—The most common Layer 2 WAN encapsulation uses the HDLC standard. Frame Relay Circuit switched ISDN 2. and communication servers.1 and 2. Make sure that the RAM. there are three types of HDLC frames: ■ Unnumbered frame—This frame is for line setup messages. you are connected to the provider’s nearest exchange. As discussed on Day 24. over the local loop or last mile. PPP.25. and Table 18-3 displays the data link layer standards for a WAN.1–1. .1.3—As review from Day 24. or central office (CO). Link Access Procedure Balanced (LAPB) Packet switched X. Table 18-2 displays the physical layer standards for a WAN. ■ Information frame—This frame holds data. You commonly use a High-Speed Serial Interface (HSSI) to a CSU/DSU. Routers often act as a gateway from your LAN to a WAN. CCNA 4.16_1587131749_DAY18.1. NVRAM. and router interfaces are capable of supporting the specific WAN service that you choose.4—Connections and protocols specific to a WAN operate at OSI Layers 1 and 2.35 48 kbps X. Module 1 1.1.

qxd 7/28/06 8:55 AM Page 79 Day 18 79 2. 2. you can use a dedicated circuit and buy a fractional T1/E1 through T3/E3 or DSL.25 or Frame Relay ■ Cell-switched as Asynchronous Transfer Mode (ATM) If you choose packet switching and if your bandwidth requirements are low. Packetswitched networks can be connectionless or connection-oriented. ■ Frame Relay is an example of a Layer 2 WAN connection-oriented packet-switching system where the route is determined by switches and each frame carries an identifier called a datalink connection identifier (DLCI). When a virtual circuit needs to exist forever.8—Table 18-4 provides a detailed menu of WAN services that you could serve to your client.5—The phone system requires continuous connections and is considered a circuit-switched system. you can save money if you request an SVC instead of a PVC. A connection that shares capacity by switching packets for many nodes is called a packet-switched network (PSN). but for data communication it is possible for many computers to share a connection and take turns requesting and receiving data as packets in short bursts. Table 18-4 WAN Service Menu WAN Service Media and Devices Features Analog dial-up Modem uses copper and connects over the local loop to the PSTN. continues . Works well for e-mail and small reports.1–2. Simple.2. You can refer to a temporary virtual circuit as a switched virtual circuit (SVC). BRI provides two 64 kbps B channels and one 16 kbps D channel. low bandwidth.6—To connect to a WAN. the provider can allow you to share a physical link with other subscribers. low cost. 56 kbps maximum bandwidth.1.1.2. it is called a permanent virtual circuit (PVC).16_1587131749_DAY18. PRI provides 23 B channels and one 64 kbps D channel in the U. as outlined in the following two examples: ■ The Internet is an example of a connectionless packet-switched system where each packet contains full addressing information. highly available. Quick setup using the D channel and high-bandwidth capabilities.. With an SVC.S. Slower call setup than ISDN. or you can instead choose a switched circuit as one of the following: ■ Circuit-switched in the form of ISDN or POTS ■ Packet-switched in the form of X. Frame Relay switches create a virtual circuit (VC) between communicating hosts that exists only when the frame is being transferred. 2. Intermittent connection over a dedicated circuit. Also serves as a backup for a leased line. and 30 B channels and one D channel in other parts of the world. ISDN ISDN modem uses the local loop as a digital connection to the provider.

Cost is based on a fixed bandwidth.2—Recall these key points and steps from Day 20. X. so VPN is a common way to secure the connection. CSU/DSU connection over copper or optical media. Works more efficiently than X. Frame Relay is a permanent shared connection.” when you design the WAN portion of an internetwork: ■ You will likely purchase your WAN connections from a communications provider for cost and legal reasons. Point-to-point permanent dedicated connection.3.25. Packet-switched shared service that uses private or shared virtual circuits. Very fast permanent shared connection that operates using cells rather than frames.25 network. ■ WANs function at the lower three layers of the OSI model but focus on Layers 1 and 2.5 miles). 2. Max 48 kbps bandwidth. but can also be dial-up to a Frame Relay network. often used for point-of-sale machines.1 and 2.25 Dial-up or leased-line connections to an X. Standard 53-byte cell provides low latency at a maximum bandwidth above 155 Mbps. Frame Relay Typically a leased line. ■ You must balance the cost of WAN connections with the speed necessary for your WAN to function. WAN connections are slower than LAN connections but may need to support voice and video as well as data.5 kilometers (3. fixed-capacity links with no latency or jitter. A personal firewall and VPN provide security for transmission over the Internet.3.qxd 80 7/28/06 8:55 AM Page 80 31 Days Before Your CCNA Exam Table 18-4 WAN Service Menu continued WAN Service Media and Devices Features Leased line Router serial port. Speeds up to 40 Mbps. Allows for bandwidth up to 8. “Design a Simple Internetwork Using Cisco Technology. works at the network layer. . Cost is based on the amount of bandwidth used and not a fixed bandwidth. Up to 4 Mbps bandwidth maximum with the capability for a committed information rate (CIR) in a private virtual circuit. Cable modem Cable modem and coaxial cable connect to the Internet using existing television cabling. Increase in neighborhood users can decrease bandwidth.16_1587131749_DAY18. including symmetric DSL (SDSL) and asymmetric DSL (ADSL). ATM Multiple virtual circuits can be provided over a single leased line. very expensive for a network with multiple endpoints. Uses a higher frequency than the 4 kHz voice channel to send data allowing voice and data to transmit simultaneously. Offers both private and shared virtual circuits.192 Mbps over many different varieties. DSL sends data across the Internet. DSL DSL modem copper phone lines over the local loop to a DSL Access Multiplexer (DLSAM).25 at the data link layer with frames and virtual circuits such as X. Mostly replaced by Frame Relay. The local loop must be less than 5. with private virtual circuits being most common. Residential shared broadband access providing both television and network connectivity. often capped by the provider.

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As mentioned on Day 20, you should consider the following steps to design a WAN:
Step 1

Locate LANS.

Step 2

Analyze traffic.

Step 3

Plan a topology.

Step 4

Plan bandwidth.

Step 5

Choose technology.

Step 6

Evaluate cost.

2.3.3—The most common WAN design connects a main point to branch networks in a star topol-

ogy. A partial mesh topology may also work well to provide better reliability. You would commonly use ISDN or DSL to connect a small office or home office (SOHO). You could choose Frame
Relay or leased lines to connect larger branch offices to a WAN. A short leased line that connects
each office to a Frame Relay network would cost much less than connecting each branch with long
leased lines. If you need a high-bandwidth network with low latency, consider leased lines, ATM,
or Frame Relay with a CIR or quality of service (QoS) mechanism. Remember that a shared service such as ATM or Frame Relay will cost less than a leased line.
2.3.4 and 2.3.5—If you had to connect 900 office branches, a flat WAN topology would not pro-

vide very good service. The three-layer hierarchical design provides an excellent structure for
WAN design. If you are designing for a business, you can parallel the region, area, and branch
with the core, distribution, and access layer design. The three-layer design helps you to better
implement, scale, manage, and troubleshoot a WAN. An example design you could implement
would be to connect branches with Frame Relay to regions that use an ATM backbone to connect
to the main office. Use the structure of the three-layer model to help define bandwidth and organizational aspects of a WAN. You can always adjust the layers to fit your specific topology and focus
on only two layers for a network that best fits that design.
2.3.6—How your WAN connects to the Internet is a key security factor in your design. If you

connect to the Internet at an office only, then you have only one connection to secure, but all
Internet traffic must pass over your WAN connections to branch offices. If each branch connects to
the Internet, you have less WAN traffic but more vulnerable points on your WAN. Some companies tunnel WAN traffic only over Internet connections, which saves connectivity costs and enables
more spending on added security.

CCNA 4, Module 3
3.1.1–3.1.4—WAN serial communication requires that frames are sent one bit at a time over the

wire. Serial communication standards include RS-232-E, V.35, and HSSI. Multiple devices and
users can connect with a single serial connection using time division multiplexing (TDM). Each
transmitting device has a time slot on the serial connection that it can use to transmit. In the United
States, you are responsible for maintaining the CSU/DSU at the demarcation point. A router that
you connect to the CSU/DSU is considered the customer premises equipment (CPE). In other
countries, the network terminating unit (NTU) is managed by the communications provider.

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Typically, your CPE router is considered the DTE, and the communication provider has the DCE
equipment and provides clocking.
3.1.5—Cisco HDLC encapsulation, as mentioned previously in the section “CCNA 4, Module 2”
under 2.1.4, is the default Layer 2 encapsulation for a serial link and defines an unnumbered,
information, and supervisory frame. Cisco HDLC uses synchronous serial transmission and supports multiple protocols using a proprietary type field as a Layer 3 protocol field.
3.2.1–3.2.6—PPP is a layered protocol that provides transmission for multiple network layer pro-

tocols and tests connectivity using the data link layer. You can configure PPP to operate on asynchronous serial, synchronous serial, HSSI, and ISDN. PPP uses the Link Control Protocol (LCP)
to establish the link and the Network Control Protocol (NCP) to configure the Layer 3 protocols.
LCP includes the following options:

Authentication—You can require the device making the call to authenticate using the clear
text Password Authentication Protocol (PAP) or the more secure and encrypted Challenge
Handshake Authentication Protocol (CHAP). PAP authenticates only once, while CHAP frequently rechecks the authentication.

Compression—This option can increase throughput on the link, and the receiving device
decompresses the frames. Stacker and Predictor are two types of compression available on a
Cisco router.

Error detection—Quality and Magic Number options can help keep the link reliable.

Multilink—This option allows for load balancing over multiple PPP-configured router interfaces. This feature is available with Cisco IOS Software Release 11.1 and later.

PPP callback—This security feature allows the client to first call and then request the router
to call back with a specific configuration. This feature is available with Cisco IOS Software
Release 11.1 and later.

NCP uses a separate protocol to control each network layer protocol. An example would be that,
for IP, NCP uses IP Control Protocol (IPCP). A PPP frame consists of a flag field, an address field,
a control field, a protocol field, a data field, and a frame check sequence (FCS) field. Table 18-5
describes each of the phases of the PPP session establishment.
Table 18-5

PPP Session Establishment

Phase

Description

Link establishment phase

Each device sends LCP frames, and they negotiate LCP options; then
LCP opens the connection with a configuration acknowledgment frame.

Authentication phase (optional)

The established link can authenticate using PAP or CHAP and also check
link quality.

Network layer protocol phase

PPP devices send NCP packets to configure network layer protocols and
allow Layer 3 transmission.

Inactivity timers, user intervention, and NCP or LCP frames can close a PPP link.

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CCNA 4, Module 4
4.1.1–4.1.3—Local carriers use ISDN to provide a digital connection on the local loop for a subscriber that allows you to exceed the 56 kbps bandwidth barrier of an analog connection. ISDN
BRI has two B channels at 64 kbps for data and one D channel at 16 kbps for call setup. ISDN can
use PPP encapsulation. The three categories for ISDN protocols are as follows:

E Series—Telephone network standards

I Series—ISDN concepts and terminology

Q Series—How switching and call setup (signaling) function, including Q.921 link access
procedure on the D channel (LAPD) and the Q.931 ISDN network layer

ISDN uses out-of-band signaling, which means that the D channel handles call setup using LAPD
outside of the data paths in the B channels. As described in Table 18-4, ISDN can provide 2 B
channels and 1 D channel with BRI or 23 B channels and 1 D channel with PRI. Outside of
America and Japan, PRI offers 30 B channels. ISDN PRI provides the same service as a T1/E1
connection. Table 18-6 outlines the fields of an ISDN frame.
Table 18-6

ISDN Frame Fields

Field

Description

Flag

Beginning of the frame.

Address Contains the following information:
Service access point identifier (SAPI)—Identifies the Layer 3 portal
Command and response (C/R) bit—Identifies whether the frame has a command or response bit
Extended addressing (EA) bits—Identifies if the address is 1 byte or 2 bytes
Terminal endpoint identifier (TEI)—Unique equipment identifier
Control

Similar to HDLC.

Data

Encapsulated data for upper layers.

FCS

Frame Check Sequence allows a check for damaged frames using a cyclic redundancy check
(CRC).

Flag

End of the frame.

4.1.4—To establish a BRI or PRI call, the D channel first sends the called number to the ISDN
switch. The local switch uses the Signaling System 7 (SS7) signaling to set up a path. The remote
switch signals the destination over the D channel. The destination NT1 device sends the remote
ISDN switch a call-connect message, and the remote ISDN switch uses SS7 to send a call-connect
to the local switch. The local switch connects one B channel for end-to-end communication. The
other B channel is available for a later connection. In essence, ISDN switches use the D channel
and SS7 signaling to establish data links on the B channel.
4.1.5—The ISDN reference points on a chart resemble alphabet soup. Either you have a terminal
equipment 1 (TE1) device with a native ISDN interface or a terminal equipment 2 (TE2) device

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that requires a terminal adapter (TA) to connect to ISDN. The following two written examples and
Figure 18-1 depict each of the ISDN reference point locations based on your TE1 or TE2:

You have a TE1 that is a native ISDN interface that connects at the S reference to the customer switching network termination type 2 (NT2). The NT2 connects at the T reference to
the network termination type 1 (NT1), and the NT1 connects at the U reference to the local
loop.

You have a TE2 that is nonnative ISDN, so you first connect at the R reference to the TA and
then to the NT2. The NT2 connects at the T reference to the NT1, and the NT1 connects at
the U reference to the local loop.

S and T references can be similar, so you may sometimes see an S/T interface.
Figure 18-1

ISDN Reference Points

S

NT2

TE1

TE2

Existing
Terminal

T

NT1

U

Service
Provider Network

Local
Loop

R

TA

Terminal
Adapter

4.1.6 and 4.1.7—When determining the appropriate ISDN interface on a router, remember the

following:

Look at the back of the router and determine if there is a BRI interface or BRI WAN interface
card (WIC).

Determine whether or not you have to provide the NT1 device to terminate the local loop to
the CO. In the United States, you will have to provide the NT1; in other countries, the
provider supplies the NT1.

If the router has a U interface, the NT1 is built in, but if the router has an S/T interface, it
needs an external connector.

If the router has a BRI interface and does not have an NT1 built in, it will need to connect to
an NT1.

If the router has only serial interfaces, it is a TE2 and will need a TA to connect to the NT1.

To connect to the provider, make sure that you have the switch type and the service profile identifiers (SPIDs) for the provider. SPIDs are used in North America and Japan to identify the B channel. SPIDs resemble phone numbers.

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CCNA 4, Module 5
5.1.1—Frame Relay is a packet-switched, connection-oriented, data link layer WAN technology.

Frame Relay uses a subset of HDLC called Link Access Procedure for Frame Relay (LAPF) for
encapsulation. Once the frame is forwarded from the DTE router to a DCE Frame Relay switch,
the network of Frame Relay switches moves the data to its destination. Typically, you will subscribe to a network of trunked Frame Relay switches owned by a public carrier.
5.1.2—The following process would allow you to connect LAN1 to LAN2 across town using
Frame Relay:

1. You call the phone company and connect your LAN1 router to their nearest Frame Relay
switch. Your LAN1 router will have a unique DLCI that identifies it on the Frame Relay
switch network.
2. You then connect the LAN2 router to a nearby Frame Relay switch on the same phone company network. LAN2 will also have a DLCI that identifies it on the Frame Relay network.
3. The phone company uses its Frame Relay switches to then establish a packet-switched PVC
across town for your two LANs.
4. The routers on LAN1 and LAN2 operate as Frame Relay access devices (FRADs).
5.1.3—Frame Relay receives a packet from a Layer 3 protocol and encapsulates it as a Layer 2
frame to transfer over the Frame Relay network. If a frame does not match its FCS upon delivery,
the frame is simply dropped and error control is left for the upper layers.
5.1.4—Your initial connection to a Frame Relay network will commonly be over a leased line.
The provider determines the bandwidth of the leased line and can also provide a CIR for your
PVC on the Frame Relay network. It is possible for your network to use more than your CIR on
the Frame Relay network, but every allowed frame that is over the CIR will be marked as discard
eligible (DE) with a 1 in the DE bit of the address field. These DE frames will be dropped first if
congestion occurs. Frame Relay switches avoid congestion by using an explicit congestion notification (ECN) bit in the frame address field. The Frame Relay switch will set the Forward ECN
(FECN) bit and Backward ECN (BECN) bit on received and sent frames to notify the DTEs to
reduce flow.
5.1.5—Routers that you connect to a Frame Relay network receive a DLCI to identify the virtual
circuit (VC). You can configure a physical interface to support multiple VCs and multiple DLCIs.
Remember that the DLCI for each VC must be associated with the network address of its remote
router. The DLCI associations or mappings can be configured using map commands or automatically with inverse ARP.
5.1.6—The 10-bit DLCI field in a Frame Relay frame permits VC identifiers 0 through 1023.
Some of these identifiers are reserved for link management identifiers (LMIs). LMIs allow DTEs
to exchange information and dynamically learn information about the status of the network. Cisco
routers support Cisco, ANSI, and Q933a-type LMIs. LMI 0 is used by ANSI and q933a, and LMI
1023 is used by Cisco. LMI messages are slightly different from the regular LAPF frames. LMI
frames include information about the status of a DLCI.

Your well-rounded knowledge of the physical. exam #640-801). logical. you will at some point be required to defend your decision. You can review everything but WAN costs in a more flashy format by reading pages 174–196. You will probably have to talk about cost. 488–502. and 548–564 in the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study. Frame Relay. The router can map VCs to network layer addresses by sending an inverse ARP message to each VC and including its own network layer address. The connected router can use the inverse ARP replies to populate its DLCI map table. or two cans and a string. A router will send inverse ARP messages for each network layer protocol. ISDN.16_1587131749_DAY18. and design aspects of each WAN service will serve you well. The network responds with details of every VC configured on the link.1. but that changes regularly and is not covered in the CCNA.qxd 86 7/28/06 8:55 AM Page 86 31 Days Before Your CCNA Exam 5. Summary Whether you decide to use dial-up. Second Edition.7—A router that is connected to a Frame Relay network will send LMI status inquiry mes- sages to the network. Your Notes . 520–532.

qxd 7/28/06 8:55 AM Page 87 Part III 17–9 Days Before the Exam— Implementation and Operation Day 17: Configure Routing Protocols Given User Requirements Day 16: Configure IP Addresses. Subnet Masks. and Gateway Addresses on Routers and Hosts Day 15: Configure a Router for Additional Administrative Functionality Day 14: Configure a Switch with VLANs and Interswitch Communication Day 13: Implement a LAN Day 12: Customize a Switch Configuration to Meet Specified Requirements and Manage System Image and Device Configuration Files (Two Objectives) Day 11: Perform an Initial Configuration on a Router and Perform an Initial Configuration on a Switch (Two Objectives) Day 10: Implement Access Lists Day 9: Implement Simple WAN Protocols .17_1587131749_Pt3.

17_1587131749_Pt3.qxd 7/28/06 8:55 AM Page 88 .

0 255. Subnet Masks. or even better. On the CCNA exam.18_1587131749_DAY17. It is very important that you become accustomed to recognizing the command mode from the prompt.1. CCNA 2. The days that cover configuration and troubleshooting will help you to quickly orient your knowledge while reading snippets of configuration information.168.” Most routing configurations start in global configuration mode.2 . the e-labs. “Configure IP Addresses.255.168. You will cover interface configuration on a Day 16.1. Consider the information provided here a primer for hands-on review in the lab or with a simulator. Module 1 1.1. 2.0 192. 6. as well as the syntax and examples. CCNA 2.qxd 7/28/06 8:55 AM Page 89 Day 17 Configure Routing Protocols Given User Requirements The configuration and troubleshooting CCNA exam objectives that introduce configuration commands in this book will provide a quick definition for a set of commands. Routing protocol configurations will only work once you have configured the interfaces on a router. Modules 1. Do not practice on your gateway router at work.255. ■ Use dynamic routing for ease of configuration and static routes for specific routing needs. you should also practice with a simulator. on real routers at your academy. you should keep the following points in mind as you configure the routers: ■ Maintain consistent addressing that represents your network topologies. ■ Use protocols that will select the best path. and Gateway Addresses on Routers and Hosts. Module 6 6. To master these commands. Today.3—The syntax for a static route follows: ip route destination-network subnet-mask {outgoing-interface | next-hop-address} Example 17-1 Configuring a Static Route Router(config)#ip route 192. These chapters help you to recognize and remember the commands. and 3 from CCNA 3 discuss routing protocol configurations. you review the syntax for a routing protocol configuration and see examples of how the commands should look in the command-line interface (CLI).1. and 7 from CCNA 2 and Modules 1.3—When you have connected all the cables and devices that constitute a WAN. you will encounter portions of a routing configuration and partial sets of commands.

2—The syntax to enable and configure Routing Information Protocol (RIP) is as follows: router rip network directly-connected-network Example 17-4 Configuring RIP Router(config)#router rip Router(config-router)#network 192.2.4—The syntax for a default route follows: ip route 0.qxd 90 7/28/06 8:55 AM Page 90 31 Days Before Your CCNA Exam 6.2.0 s0 6.7—The following command syntax prevents routing updates from transmitting on an interface: router rip passive-interface interface Example 17-6 The passive-interface Command Router(config)#router rip Router(config-router)#passive-interface fa0/0 .0 {outgoing-interface | next-hop-address} Example 17-2 Configuring a Default Route Router(config)#ip route 0.18_1587131749_DAY17. Example 17-5 The ip classless Command Router(config)#ip classless 7.1.168.5—The commands shown in Example 17-3 allow you to check your static and default routes.3—The ip classless command shown in Example 17-5 allows a router to ignore network class boundaries.2.0 0.0.0.168.0.0.1. Module 7 7.0 7.0. The ip classless command is on by default on most routers.2.0 0.0 Router(config-router)#network 192.0. Example 17-3 Verifying Static and Default Routes Router#show running-config Router#show ip route CCNA 2.0.1.0.

10—You can dictate the priority of a route using the administrative distance (AD).255. The following command increases the AD of a static route to 130 so that a dynamic route with an AD of 120 will take priority in the routing table. Example 17-10 Removing a Static Route Router(config)#no ip route 192. use the following syntax: interface interface no ip route-cache Example 17-8 Setting an Interface to Route on a Per-Packet Basis Router(config)#interface s0/0 Router(config-if)#no ip route-cache 7.168.0 255. as shown in Example 17-10.2.0 192.3.168.168.qxd 7/28/06 8:55 AM Page 91 Day 17 91 7.255.255.2. The following com- mand sets the number of paths: router rip maximum-paths {0-6} Example 17-7 Setting Load Balancing Maximum Paths Router(config)#router rip Router(config-router)#maximum-paths 3 To tell a router to load balance on a per-packet basis rather than a per-destination basis.18_1587131749_DAY17.9—RIP can load balance traffic over up to six network paths.1.5—The following commands allow you to enable and configure Interior Gateway Routing Protocol (IGRP): router igrp autonomous-system-number network directly-connected-network .0 255. You add the administrative distance option to the end of your static route configuration. Example 17-9 Configuring a Static Route with an Administrative Distance Router(config)#ip route 192.168.0 192.1.2.8 and 7.1.255.1.2 7.2 130 You can also remove a static route by adding a no in front of the command.

1.2. The configuration of the correct mask allows the routing protocol to advertise the right mask with each network.168. 1. you can view information about the protocols and verify IGRP configuration with the commands shown in Example 17-12.1.168.168.0 7.255.4 and 1.2.7—IGRP has an administrative distance of 100 and will take priority over RIP entries in a routing table. you can configure a routing protocol such as RIP version 2 that supports VLSM.6—Although variable-length subnet mask (VLSM) support is a component of a routing proto- col.3. Example 17-12 Viewing Configured Protocols Router#show ip protocols Router#show ip route Router#show running-config Router#show interface CCNA 3.252 Once you have configured all the interfaces with the proper subnet masks.18_1587131749_DAY17. You would use the following interface configuration syntax on a serial interface with a point-to-point connection that requires only a two-host network: ip address ip-address subnet-mask Example 17-13 Configuring an Interface with VLSM Router(config)#interface serial 0 Router(config-if)#ip address 192. Module 1 1.3.qxd 92 7/28/06 8:55 AM Page 92 31 Days Before Your CCNA Exam Example 17-11 Configuring IGRP Router(config)#router igrp 101 Router(config-router)#network 192.2 255.2. you need to configure the interface with the proper subnet mask in order for routing with VLSM to work properly.5—RIP version 2 configuration syntax is as follows: router rip version 2 network directly-connected-network .0 Router(config-router)#network 192.255. If you have a router with both protocols configured.0.6 and 7.

The loopback interface should be configured with a host mask. in which case the highest loopback IP address will become the router ID.168. Loopbacks are used to ensure that a router always has an active interface. The following command configures the loopback interface to guarantee OSPF reliability: ip address ip-address subnet-mask Example 17-16 Configuring the Loopback Interface with a Host Mask Router(config)#interface loopback 0 Router(config-if)#ip address 192.0.3.168.1.qxd 7/28/06 8:55 AM Page 93 Day 17 93 Example 17-14 Configuring RIP Version 2 Router(config)#router rip Router(config-router)#version 2 Router(config-router)#network 192.0.0 0.0.0 0. Module 2 2.255.168.2—OSPF uses the highest local IP address as its router ID unless a loopback interface exists.255.9 255.255 area 0 2. CCNA 3.0.3.0.1. To control the designated router election process.168. which is a 32-bit mask.1—The following is the command syntax for Open Shortest Path First (OSPF): router ospf process-id network network-address wildcard-mask area area-id Example 17-15 Configuring OSPF Router(config)#router ospf 1 Router(config-router)#network 192.255 area 0 Router(config-router)#network 192.2. and the highest priority wins.18_1587131749_DAY17. you can set the OSPF priority with the following configuration: ip ospf priority {0-255} Example 17-17 Configuring the OSPF Router Priority Router(config)#interface serial 0 Router(config-if)#ip ospf priority 40 .0 Just as with RIP and IGRP.255 All OSPF routers have a default priority of zero. you can verify RIP version 2 configuration with the commands listed previously in Example 17-12.

You can control the priority of the link on your network with the following commands: bandwidth bandwidth ip ospf cost {1-65.4—The following commands will configure simple OSPF authentication: ip ospf authentication-key password area area-number authentication Example 17-21 Configuring Simple OSPF Authentication Router(config)#interface serial 0 Router(config-if)#ip ospf authentication-key cisco Router(config-if)#exit Router(config)#router ospf 1 Router(dhcp-config)#area 0 authentication The following commands configure OSPF authentication with MD5 encryption: ip ospf message-digest-key key-id md5 key area area-number authentication message-digest .18_1587131749_DAY17.3—You can control the priority of an OSPF route by adjusting the bandwidth and cost.qxd 94 7/28/06 8:55 AM Page 94 31 Days Before Your CCNA Exam You can verify OSPF priority configuration with the following command: show ip ospf priority interface interface Example 17-18 Verifying the OSPF Router Priority Configuration Router(config)#show ip ospf interface serial 0 2.3. You can override this calculation by manually setting the cost. Altering the bandwidth alters the cost.535} Example 17-19 Configuring the Bandwidth of an Interface Router(config)#interface serial 0 Router(config-if)#bandwidth 64 Example 17-20 Configuring the OSPF Cost for an Interface Router(config)#interface serial 0 Router(config-if)#ip ospf cost 1 2. OSPF automatically calculates the interface cost based on bandwidth.3.

0.qxd 7/28/06 8:55 AM Page 95 Day 17 95 Example 17-22 Configuring OSPF Authentication with MD5 Encryption Router(config)#interface serial 0 Router(config-if)#ip ospf message-digest-key 1 md5 cisco Router(config-if)#exit Router(config)#router ospf 1 Router(dhcp-config)#area 0 authentication message-digest 2.0 0.0 {interface |next-hop-address} default-information originate Example 17-24 Propagating a Default Route with OSPF Router(config)#ip route 0.3.18_1587131749_DAY17.0 0.0 serial 0 Router(config)#router ospf 1 Router(config-router)#default-information originate 2. but if you would like.8—You can check OSPF operation and configuration using the following show.0.7–2.0.3.0.6—To add a default route and then propagate that route with OSPF. and debug commands: show ip protocol show ip route show ip ospf interface show ip ospf show ip ospf neighbor detail show ip ospf database clear ip route * clear ip route next-hop-address debug ip ospf events debug ip ospf adj .3.0.5—You must have the same hello and dead timer intervals in OSPF in order for your routers to exchange information. These values work fine. you can change them with the following commands: ip ospf hello-interval seconds ip ospf dead-interval seconds Example 17-23 Configuring OSPF Hello and Dead Intervals Router(config)#interface serial 0 Router(config-if)#ip ospf hello-interval 5 Router(config-if)#ip ospf hello-interval 20 2.0. clear.0. The default values are 10 seconds for a hello and 40 seconds for a dead interval timer.3. use the following commands: ip route 0.0.

1.2.0.168.0.0 .255.2.0 Router(config-router)#network 192.18_1587131749_DAY17.0 Router(config-router)#eigrp log-neighbor-changes The following command configures EIGRP bandwidth: bandwidth bandwidth Example 17-26 Configuring EIGRP Bandwidth Router(config)#interface serial 0 Router(config-if)#bandwidth 56 3.1—The following commands enable Enhanced Interior Gateway Routing Protocol (EIGRP) and configure bandwidth and logging: router eigrp autonomous-system-number network network-number eigrp log-neighbor-changes Example 17-25 Configuring EIGRP and Logging Router(config)#router eigrp 10 Router(config-router)#network 192. Module 3 3.16.168.2.0 255. you can use the following command: no auto-summary Example 17-27 Turning Off EIGRP Route Summarization Router(config)#router eigrp 10 Router(config-router)#no auto-summary You can also manually configure a summary address with the following command: ip summary-address eigrp as-number ip-address mask administrative-distance Example 17-28 Manually Configuring EIGRP Route Summarization Router(config)#interface serial 0 Router(config-if)#ip summary-address eigrp 10 172.2—If you want to turn off route summary in EIGRP for subnets that are not continuous.qxd 96 7/28/06 8:55 AM Page 96 31 Days Before Your CCNA Exam CCNA 3.

qxd 7/28/06 8:55 AM Page 97 Day 17 97 3. Pages 388–454 from the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study. IGRP. Second Edition.2. exam #640-801). but sitting at a router or simulator will internalize the steps and commands. Skimming through these examples will help jog your memory.” from concepts to configuration.18_1587131749_DAY17.2. .2.” EIGRP uses the diffusing update algorithm (DUAL) to maintain a neighbor table and topology table of available routes. The successor route is considered the best route and is added to the topology table as well as the routing table.3—The following show commands allow you to verify EIGRP: show ip eigrp neighbors show ip eigrp interfaces show ip eigrp topology 3. “Evaluate the Characteristics of Routing Protocols. A backup route called the feasible successor is kept in the topology table. OSPF.7—As discussed on Day 28. can give you a great overview of everything “routy. Summary The configurations for RIP. and EIGRP should at this point be easy to recognize and use if you intend to be CCNA test ready.4–3.

qxd 98 7/28/06 8:55 AM 31 Days Before Your CCNA Exam Your Notes Page 98 .18_1587131749_DAY17.

but the masks and interface addresses you choose for your routers are pillars in your logical network design. To configure an IP on a router interface. a lifetime to address. Your knowledge of IP addressing. Subnet Masks. You need to configure IP addresses and subnet masks on both hosts and routers to complete a network. Module 1 1. You can assign an address to a host using the operating system or configure the host to obtain the IP address automatically. and variable-length subnet masks (VLSMs) converge when you decide to configure an IP address and mask on your router interface. Remember to apply the conventions in IP addressing covered on those days when you configure the interfaces on a router and your network hosts.1—To use the CLI on a router. you can use Cisco IOS software. and Modules 1 and 2 from CCNA 3 outline the various interface configuration commands. Modules 1 and 9 from CCNA 1.6—Routers and hosts use TCP/IP to communicate across a network.7—On Day 27.1. CCNA 1.1. Figure 16-1 and Table 16-1 provide examples of the modes available to you for router configuration.qxd 7/28/06 8:56 AM Page 99 Day 16 Configure IP Addresses. you must know the hierarchy of configuration modes. “Design an IP Addressing Scheme to Meet Design Requirements. “Evaluate the TCP/IP Communication Process and Its Associated Protocols. CCNA 2. . Consider the information provided here a primer for hands-on review in the lab or with a simulator. you review the syntax for interfacerelated configuration commands and see examples of how the commands should look in the command-line interface (CLI).19_1587131749_DAY16. Today.” you reviewed the proper dotted decimal format for an IP address and subnet masks.1–9. CCNA 1.2. subnetting. Module 9 9. Module 3 from CCNA 2.2. The configuration is simple and short. Module 3 3. routing protocols. and Gateway Addresses on Routers and Hosts A minute to configure.” and Day 22.

Example 16-1 Entering Interface Configuration Mode for Serial 0 Router>enable Router#configure terminal Router(config)#interface serial 0 Router(config-if)# 3.5—You use the following command syntax to configure a serial interface.qxd 100 7/28/06 8:56 AM Page 100 31 Days Before Your CCNA Exam Figure 16-1 Router Modes Router> • User EXEC mode • Privileged EXEC mode Router# • Global configuration mode • Specific configuration modes Router (config) # Table 16-1 Configuration Modes and Prompts Configuration Mode Prompt Interface Router(config-if)# Subinterface Router(config-subif)# Controller Router(config-controller)# Map-list Router(config-map-list)# Map-class Router(config-map-class)# Line Router(config-line)# Router Router(config-router)# IPX-router Router(config-ipx-router)# Route-map Router(config-route-map)# Example 16-1 shows the commands you would use to enter interface configuration mode. interface type slot/port ip address ip-address netmask clock rate clock-rate no shutdown . You use the clock rate command only if you are configuring a data communications equipment (DCE) interface.19_1587131749_DAY16.1.

The following commands allow you to add an interface description: interface type slot/port description interface-description .255.255.6—You can use the no form of a command to remove the configuration. including all interface configurations. and save the configuration to nonvolatile RAM (NVRAM) by using the following commands in global configuration mode: show running-config copy running-config startup-config 3. A good start is to add a description to each interface so that you or anyone configuring the router can quickly identify the purpose and location of the interface.16.2.255.7—You use the following command set to configure an Ethernet interface: interface type slot/port ip address ip-address netmask no shutdown Example 16-4 Configuring an Ethernet Interface Router(config)#interface fastethernet 0/0 Router(config-if)#ip address 172.2.1 255.19_1587131749_DAY16.1.255.1.16.1 255. Example 16-3 Removing Previously Entered Configurations Router(config)#interface serial 0/0 Router(config-if)#no ip address 172.1 255.255.0 Router(config-if)#no shutdown 3. Example 16-3 would remove the IP address and clock rate from the interface configured in Example 16-2 and shut down the interface.2.qxd 7/28/06 8:56 AM Page 101 Day 16 Example 16-2 101 Configuring a Serial Interface Router(config)#interface serial 0/0 Router(config-if)#ip address 172.1–3.255.1.1.16.0 Router(config-if)#clock rate 56000 Router(config-if)#no shutdown 3.0 Router(config-if)#no clock rate 56000 Router(config-if)#shutdown You can always check your entire configuration.3—Keeping good standardized documentation of your router configurations is impera- tive for an organized network.

qxd 102 7/28/06 8:56 AM Page 102 31 Days Before Your CCNA Exam Example 16-5 Configuring a Description for an Ethernet Interface Router(config)#interface fastethernet 0 Router(config-if)#description Accounting LAN. If you have more than one loopback device configured.255. “Configure Routing Protocols Given User Requirements. CCNA 3. Module 1 1.0.0.9 255.2—As mentioned on Day 17.” you can configure routers with VLSM in networks to more efficiently use IP addresses. Floor 11 When you have completed an interface configuration.1. Example 16-8 Configuring the Loopback Interface with a Host Mask Router(config)#interface loopback 0 Router(config-if)#ip address 192.3.255.168. Also remember to copy your running configuration to NVRAM in order to save the changes you have made. you can change modes back to privileged exec quickly using Ctrl-Z. Open Shortest Path First (OSPF) cannot function reliably with- out an interface that is always active.0.255. Module 2 2. or by entering the end command. OSPF will use the highest loopback IP address as the router ID.255.255. You configure the loopback interface on an OSPF router to ensure that you have an always-active interface.2 255. You might use the configurations in Examples 16-6 and 16-7 if you were running RIP version 2 and only needed two IP addresses for a serial point-to-point link and a 12-host network for a LAN.17 255.252 Example 16-7 Configuring an Ethernet Interface for a 12-Host LAN Router(config)#interface ethernet 0 Router(config-if)#ip address 172.16.255.16.240 CCNA 3.19_1587131749_DAY16.255 . Example 16-6 Configuring a Serial Interface for a Point-to-Point Link Router(config)#interface serial 0 Router(config-if)#ip address 172.6—As discussed on Day 17. Make sure that your router is running a routing protocol that supports VLSM.

Second Edition. . be sure to pay attention to the command mode for each command that you encounter.19_1587131749_DAY16. While you are practicing commands and taking curriculum practice exams. exam #640-801).qxd 7/28/06 8:56 AM Page 103 Day 16 103 Summary Routing protocols function properly only if interfaces are configured properly. You will find questions concerning command modes and interface configuration mixed in with a few other commands on pages 198–238 in the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study.

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Today.qxd 7/28/06 8:56 AM Page 105 Day 15 Configure a Router for Additional Administrative Functionality Although Layer 3 path selection is the key function of a router. network address translation (NAT). Module 3 from CCNA 2 and Modules 1 and 6 from CCNA 4 provide additional configurations for your router.20_1587131749_DAY15.1. you will need to set the virtual terminal password. there are many other parameters that you can configure. The CCNA exam covers password configuration as well as Dynamic Host Configuration Protocol (DHCP). Module 3 3. DHCP. CCNA 2. NAT. you review the syntax for password. as follows: password password login . and PAT configuration commands and see examples of how the commands should look in the command-line interface (CLI). Consider today’s information a primer for hands-on review in the lab or with a simulator.1.2—The following command allows you to set a router hostname: hostname hostname Example 15-1 Configuring a Router Hostname Router(config)#hostname Portland Portland(config)# 3. and port address translation (PAT) configurations.3—You can restrict console access to a router with the following command: password password login Example 15-2 Setting the Console Password Router(config)#line console 0 Router(config-line)#password cisco Router(config-line)#login If you intend to access a router using Telnet.

you must use the following command: enable password password Example 15-4 Setting the Password for Privileged EXEC Router(config)#enable password class To encrypt and set the privileged EXEC password. and configuration of a router: ■ show interfaces—Displays interface information ■ show controllers serial—Displays interface hardware information ■ show clock—Displays router time settings ■ show hosts—Displays hostname and address cache ■ show users—Displays connected users ■ show history—Displays previously entered commands ■ show flash—Displays flash memory and Cisco IOS file information ■ show version—Displays information about the loaded operating system as well as hardware information .qxd 106 7/28/06 8:56 AM Page 106 31 Days Before Your CCNA Exam Example 15-3 Setting the VTY Password Router(config)#line vty 0 4 Router(config-line)#password cisco Router(config-line)#login To restrict access to privileged EXEC mode.1. use the following command: service password-encryption Example 15-6 Encrypting all Unencrypted Passwords Router(config)#service password-encryption 3.20_1587131749_DAY15. set- tings. use the following command: enable secret password Example 15-5 Setting the Console Password Router(config)#enable secret class To encrypt all unencrypted passwords.4—The following show commands provide you with information about the files. access.

1.2.2.2.7—To associate a name with one or multiple IP addresses on a router. Module 1 1.4—Static NAT is designed to allow one-to-one mapping of local and global addresses.4 and 3.20_1587131749_DAY15. Example 15-9 Associating a Name with an IP Address Router#ping boise CCNA 4. you can use the following command: ip host {name} {IP-address} Example 15-8 Associating a Name with an IP Address Router(config)#ip host boise 192.1.qxd 7/28/06 8:56 AM Page 107 Day 15 ■ show arp—Displays the Address Resolution Protocol (ARP) table ■ show protocols—Displays information about presently configured Layer 3 protocols ■ show startup-config—Displays the configuration saved in the NVRAM ■ show running-config—Displays the running configuration in RAM 107 3.1 You can test your configuration by using the ping command with the new hostnames on the router that you have configured.168.5—You use the following commands to display a message before a user logs in to the router: banner motd delimiting-character banner-message delimiting-character Example 15-7 Setting a Login Banner Router(config)#banner motd # Authorized Access Only # 3. you have to add a static NAT entry and then label the outside and inside interfaces using the following commands: ip nat inside source static local-IP-address global-IP-address ip nat outside ip nat inside .33 192.6 and 3.2. To configure static NAT. as shown in Example 15-9.168.2.

225 209.165. you set NAT to use the two groups for translation with the following commands: ip nat inside source list access-list-number pool pool-name ip nat outside ip nat inside Example 15-12 Configuring Dynamic NAT Router(config)#ip nat inside source list 1 pool isp-pool Router(config)#interface serial 0 Router(config-if)#ip nat outside Router(config-if)#interface fa 0/0 Router(config-if)#ip nat inside If you configure NAT with overload.255.168.235 netmask 255.168.165. you define a pool of global addresses and then use an access list to define the range of inside addresses that are eligible to be converted with the following commands: ip nat pool pool-name start-IP-address end-IP-address netmask netmask access-list access-list-number permit inside-network wildcard-mask Example 15-11 Defining Inside and Outside Addresses for Dynamic NAT Configuration Router(config)#ip nat pool isp-pool 209.0 0.200.165.226 Router(config)#interface serial 0 Router(config-if)#ip nat outside Router(config-if)#interface fa 0/0 Router(config-if)#ip nat inside To configure dynamic NAT. You can configure overload to translate many addresses to just one outside IP address that is assigned to an interface using the following commands: access-list access-list-number permit inside-network wildcard-mask ip nat inside source list access-list-number interface interface overload ip nat outside ip nat inside .20_1587131749_DAY15.5 209.1.qxd 108 7/28/06 8:56 AM Page 108 31 Days Before Your CCNA Exam Example 15-10 Configuring Static NAT Router(config)#ip nat inside source static 192.200.0.1.255.224 Router(config)#access-list 1 permit 192. you have enabled PAT.200.255 Once you have defined a pool of outside addresses and a range of inside addresses with an access list.0.

1. the router can provide host machines with configurations such as an IP address.224 Router(config)#ip nat inside source list 1 pool isp-pool overload Router(config)#interface serial 0 Router(config-if)#ip nat outside Router(config-if)#interface fa 0/0 Router(config-if)#ip nat inside 1.0.165.255 Router(config)#ip nat pool isp-pool 209.1.235 netmask 255.0.0 0.0.6—You can also watch every packet that is translated in NAT with the following commands: debug ip nat debug ip nat detailed 1.165.20_1587131749_DAY15.255.168.1.0 0.5—You can verify NAT and PAT configurations with the following commands: show ip nat translations show ip nat statistics show running-config 1. and lease time. a DNS server.255. .1.168.255 Router(config)#ip nat inside source list 1 interface serial 0 overload Router(config)#interface serial 0 Router(config-if)#ip nat outside Router(config-if)#interface fa 0/0 Router(config-if)#ip nat inside You can also configure NAT with overload to translate a pool of addresses using the following commands: access-list access-list-number permit inside-network wildcard-mask ip nat pool pool-name start-IP-address end-IP-address netmask netmask ip nat inside source list access-list-number pool pool-name overload ip nat outside ip nat inside Example 15-14 Configuring NAT with Overload for a Pool of Outside IP Addresses Router(config)#access-list 1 permit 192.225 209.0.200.2. As a DHCP server.4—You can configure a router to handle host addressing on your LAN with DHCP.200.qxd 7/28/06 8:56 AM Page 109 Day 15 109 Example 15-13 Configuring NAT with Overload for One Outside IP Address Router(config)#access-list 1 permit 192.

168.168.2.0 255.com You can exclude a range of addresses or a single address from the DHCP pool that you wish to reserve and assign to specific hosts with the following commands: ip dhcp excluded-address start-address end-address ip dhcp excluded-address single-address Example 15-16 DHCP Pool Excluded Address Range or Specific Addresses Router(config)#ip dhcp pool excluded-address 192.168.255. which is shown in Example 15-17.4.6 and 1.qxd 110 7/28/06 8:56 AM Page 110 31 Days Before Your CCNA Exam 1.20_1587131749_DAY15.168. .4.254 Router(dhcp-config)#dns-server 192.4. you first define the DHCP pool and then provide other TCP/IP parameters with the following commands: ip dhcp pool pool-name network network-address subnet-mask default-router default-router-address dns-server dns-server-address netbios-name-server netbios-name-server-address domain-name domain-name Example 15-15 Configuring DHCP Router(config)#ip dhcp pool subnet4 Router(dhcp-config)#network 192.4.3 Router(dhcp-config)#domain-name bennettsupport.254 You can start and stop the DHCP service with these two commands: service dhcp no service dhcp 1.1 192.2. use the show ip dhcp binding command.7—To make sure that DHCP is operating.5—To configure DHCP on a router.2. which is shown in Example 15-18. Example 15-17 Displaying DHCP Bindings Router#show ip dhcp binding You can also verify that the router is sending and receiving DHCP messages with the show ip dhcp server statistics command.168.255.4.4.168.168.0 Router(dhcp-config)#default-router 192.20 Router(config)#ip dhcp pool excluded-address 192. Make sure that you test all show commands in a lab or simulation so that you are familiar with the output.4.2 Router(dhcp-config)#netbios-name-server 192.

Example 15-19 Displaying DHCP Processes Router#debug ip dhcp server events 1. you can use the following commands: snmp-server community community-string {ro | rw} snmp-server location location snmp-server community contact .2. which is shown in Example 15-19.2. as shown in Example 15-20.17.168.1 CCNA 4. This command allows you to configure a router to forward the following services: ■ Time ■ Terminal Access Controller Access Control System (TACACS) ■ Domain Name Service (DNS) ■ Bootstrap Protocol (BOOTP)/DHCP Server ■ BOOTP/DHCP Client ■ Trivial File Transfer Protocol (TFTP) ■ NetBIOS Name Service ■ NetBIOS Datagram Service Use the following command to forward a DHCP broadcast: ip helper-address address Example 15-20 Forwarding DHCP Broadcasts Across a Router Router#ip helper-address 192. you can use the ip helper-address command.8—If you have a DHCP server in a different network and would like DHCP broadcasts to for- ward across a subnet on a router. Module 6 6.qxd 7/28/06 8:56 AM Page 111 Day 15 111 Example 15-18 Displaying DHCP Message Count Router#show ip dhcp server statistics If you would like to see information about addresses returned and allocated as well as address lease information.20_1587131749_DAY15. use the debug ip dhcp server events command.7—If you have a Simple Network Management Protocol (SNMP) server running on your net- work and you would like to enable SNMP on your router.

You can benefit greatly from the advantages of using internal private addressing from both an expense and security standpoint.qxd 112 7/28/06 8:56 AM Page 112 31 Days Before Your CCNA Exam Example 15-21 Enabling SNMP on a Router Router(config)#snmp-server community campus3 ro Router(config)#snmp-server location building1A Router(config)#snmp-server contact Matt S. You can review some of these concepts in pages 475–486 in the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study. DHCP. NAT.20_1587131749_DAY15. 555-1234 The ro and rw options stand for read only and read write. exam #640-801). and PAT all provide additional functionality for your router. Your Notes . Second Edition. Summary Passwords for router access.

2—VLANs allow you to logically separate a network into Layer 3 subnets. ISL is a Cisco proprietary protocol. ■ You do not want to manage by MAC address. Amazing. you review the syntax for VLAN and VTP configuration commands and see examples of how the commands should look in the command-line interface (CLI).1 and 8.qxd 7/28/06 8:56 AM Page 113 Day 14 Configure a Switch with VLANs and Interswitch Communication Switches allow you to completely restructure your network design with a couple of keystrokes.21_1587131749_DAY14. Consider today’s information a primer for hands-on review in the lab or with a simulator. as corporations work to centralize network resources. . while IEEE 802. The switch configured for static VLANs should also be in VTP server mode. You also need to adhere to the following requirements of VLAN 1: ■ VLAN 1 is one of the factory default VLANs.3—You would configure static VLANs if your network design fits the following description: ■ You have VLAN software to configure ports. ■ You plan to control any and all moved workstations.2. Modules 8 and 9 from CCNA 3 explain the concepts and configurations behind VLANs and VTP. the switch’s IP address is in the VLAN1 broadcast domain. The flexibility of VLAN implementation provides the following features: ■ VLAN membership based on job assignment regardless of location ■ VLAN membership that follows the users when they change location on the network ■ VLAN membership that provides security settings assigned for each logical group You can configure switches to share VLAN information with frame tagging using Inter-Switch Link (ISL) or Institute of Electrical and Electronics Engineers (IEEE) 802. Today. A VLAN can be as small as a department or as large as an entire building.1Q is an open standard. Virtual LANs (VLANs) and the VLAN Trunking Protocol (VTP) allow you to avoid the myriad ports and Category 5 cable that your hub-wielding predecessors battled during their attempts to segment and scale a network. ■ VLAN 1 must carry VLAN Trunking Protocol (VTP) and Cisco Discovery Protocol (CDP) traffic.2.2.1Q. 8. Module 8 8. By default. it is most common to assign VLANs based on geographic location. ■ VLAN 1 must be the default Ethernet VLAN. CCNA 3. Although it is possible to assign VLANs based on job function.

qxd 114 7/28/06 8:56 AM Page 114 31 Days Before Your CCNA Exam The commands to create a static VLAN using the vlan database command and apply the VLAN to interfaces are as follows: vlan database vlan vlan-number interface interface switchport access vlan vlan-number Example 14-1 Configuring a VLAN Using the vlan database Command Switch#vlan database Switch(vlan)#vlan 2 Switch(vlan)#exit Switch#configure terminal Switch(config)#interface fastethernet 0/4 Switch(config-if)#switchport mode access Switch(config-if)#switchport access vlan 2 VLAN configuration is now preferred in global configuration mode rather than using the vlan database command. you can use the show running config and show vlan commands to capture VLAN configuration settings with the text capture .2.4—The following commands allow you to verify your VLAN configuration: show vlan show vlan brief show vlan id {id | name} vlan Remember that all ports are in VLAN1 by default. 8. The commands to create a VLAN and apply the VLAN to interfaces in global configuration mode are as follows: vlan vlan-number interface interface switchport mode access switchport access vlan vlan-number Example 14-2 Configuring a VLAN in Global Configuration Mode Switch#configure terminal Switch(config)#vlan 2 Switch(config-vlan)#exit Switch(config)#interface fastethernet 0/4 Switch(config-if)#switchport mode access Switch(config-if)#switchport access vlan 2 8.5—If you created your VLAN in global configuration mode.21_1587131749_DAY14.2.

the two types of frame tagging are the Cisco proprietary ISL and IEEE 802.1Q is the only encapsulation available. A switch uses frame tagging to add header information to each frame identifying the VLAN ID of that frame for other switches connected through a trunk link.1. To look at the type of trunking configured on a Catalyst 2900.1Q.21_1587131749_DAY14. The trunk link provides a single backbone connection for multiple VLANs between switches. You can also back up your VLAN configuration with the following command: copy running-config tftp 8.1–9.1. you use the no statement at the beginning of the VLAN configuration command. Module 9 9.5—The following command configures trunking on a Catalyst 2900 switch: switchport trunk encapsulation {isl | dot1q} Example 14-5 Configuring VLAN Trunking on a 2900 Switch(config)#interface fastethernet 0/12 Switch(config-if)#switchport trunk vlan isl On a Cisco Catalyst 2950.1. Two types of trunking protocols are frame filtering and frame tagging.4—A trunk between switches is a physical and logical connection that passes network traffic.qxd 7/28/06 8:56 AM Page 115 Day 14 115 feature in HyperTerminal.2. The IEEE has defined frame tagging as the standard trunking type. As mentioned previously. as shown in Examples 14-3 and 14-4. use the following command: show trunk module/port .6—To remove a VLAN. Example 14-3 Deleting a VLAN Using the vlan database Command Switch#vlan database Switch(vlan)#no vlan 2 Switch(vlan)#exit Example 14-4 Deleting a VLAN in Global Configuration Mode Switch#configure terminal Switch(config)#no vlan 2 CCNA 3. 9. Trunking protocols allow switches to send information from multiple VLANs across a single channel. you do not need this command because 802.

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Make sure that you use all the show commands in this book when you are practicing in a lab
or simulation so that you are familiar with the output.
9.2.1–9.2.3—VTP allows you to manage your VLANs with Layer 2 trunk frames. You can add,

delete, and rename VLANs using VTP. You can configure VLANs to be encapsulated in ISL or
802.1Q frames. VTP messages always contain the following items:

VTP protocol version

VTP message type

Management domain length

Management domain name

Table 14-1 outlines the three possible modes for a VTP switch.
Table 14-1

VTP Switch Modes

VTP Mode

Capabilities

Definition

Server

Can create, modify, and delete VLANs

Sends VTP messages out all trunk ports and
saves VLAN configuration in the NVRAM.

Client

Cannot create, modify, and delete VLANs

Better for switches that do not have enough
memory for large configurations. VTP clients
process changes and forward messages.

Transparent

Only forwards advertisements

Forwards the messages, but does not modify its
own independent VLAN database.

VLAN modifications occur only in the VTP domain where they originate. The configuration revision number of a VTP update determines whether or not a switch will overwrite its database. The
switch overwrites its database information using the most recent update with the highest configuration revision number. VTP maintains its own NVRAM, and the configuration register can only be
reset if you clear the NVRAM and reboot the switch. By default, VTP does not operate in secure
mode.
9.2.4—Switches use VTP to multicast the following information:

Management domain

Configuration revision number

Known VLANs

Known VLAN parameters

Once you have set up a VTP domain, you need to configure only one device, and all the other
devices learn from this device. VTP advertisements start with the configuration register number 0,
increase by 1 until they reach 2,147,483,648, and then start again at 0. VTP advertisements are
either a request from a client or a response from a server. The three types of VTP messages are as
follows:

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117

Advertisement requests—Clients request VLAN information.

Summary advertisements—The switch sends summary advertisements every five minutes.
A switch updates its database only if the configuration revision number is higher than the
switch’s current revision number.

Subset advertisements—Subset advertisements are triggered by changes to VLAN settings
such as creation or deletion. These advertisements provide specific information about
VLANs.

9.2.5—To set up VTP, you need to configure the version number, the VTP domain, the VTP

mode, and a password with the following commands:
vlan database
vtp v2-mode
vtp domain domain
vtp {client | server | transparent}
vtp password password

Example 14-6

Configuring a VTP Server

Switch#vlan database
Switch(vlan)#vtp v2-mode
Switch(vlan)#vtp domain group3
Switch(vlan)#vtp server
Switch(vlan)#vtp password cisco

Once you have completed the VTP configuration, you can quickly check it with the following
commands:
show vtp status
show vtp counters

9.3.2–9.3.6—You need to use a Layer 3 router in order to allow devices to communicate across
VLANs. You can connect a physical router interface to each VLAN just as you would connect
router interfaces to separate switches, or you can use one physical interface and configure logical
subinterfaces for each VLAN. If your router has one 100 Mbps connection to a switch with
VLANs 1, 20, and 30, you can configure the interface with the following commands for each
subinterface:
interface fastethernet slot-number/port.subinterface-number
encapsulation dot1q vlan-number
ip address ip-address subnet-mask

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Example 14-7

Router VLAN Subinterface Configuration

Router(config)#interface fastethernet 0/0.1
Router(config-if)#encapsulation dot1q 1
Router(config-if)#ip address 192.168.1.1 255.255.255.0
Router(config)#interface fastethernet 0/0.2
Router(config-if)#encapsulation dot1q 20
Router(config-if)#ip address 192.168.2.1 255.255.255.0
Router(config)#interface fastethernet 0/0.3
Router(config-if)#encapsulation dot1q 30
Router(config-if)#ip address 192.168.3.1 255.255.255.0

In Example 14-7, as always, VLAN1 is the management VLAN. It cannot be deleted and carries
VTP and CDP.

Summary
Most switches work right out of those cool Cisco shipping boxes, but a true CCNA (or CCNA in
training) would strive to implement the additional features available in a switch. You can divide the
network logically with VLANs and then push that configuration across multiple switches with
VTP. Another source for review of today’s material can be found in pages 111–120 and 350–386
in the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study, exam #640-801), Second
Edition.

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Your Notes

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and you typically need to purchase bandwidth for your WAN connection. that do not fit well elsewhere. 4. LAN bandwidth is faster than WAN bandwidth. 5.22_1587131749_DAY13. your LAN will operate at 100 Mbps.7—Bandwidth represents the amount of data you can transfer over a network. and 7 from CCNA 1 provide information about LAN implementation. However.000. such as bandwidth and cabling. Coaxial 10 500 meters 10BaseT Ethernet Category 5 UTP 10 100 meters 100BaseTX Ethernet Category 5 UTP 100 100 meters 1000BaseTX Ethernet Category 5 UTP 1000 100 meters 100BaseFX Ethernet Multimode Optical Fiber 100 or 1000 220 meters 1000BaseSX Ethernet Multimode Optical Fiber 1000 550 meters 1000BaseLX Ethernet Singlemode Optical Fiber 1000 5000 meters . Table 13-2 Bandwidth Units Media Type Bandwidth in Mbps Maximum Distance 10Base2 Ethernet Thinnet. seems about as easy to pin down for details as implementing world peace. Module 2 2.000 bits per second Gigabits per second Gbps 10 bits per second Terabits per second Tbps 10 bits per second 9 12 Category 5 (Cat 5) unshielded twisted pair (UTP) copper cabling is presently physically limited to 1 Gbps. this objective provides a good opportunity to talk about some LAN topics.qxd 7/28/06 8:56 AM Page 121 Day 13 Implement a LAN Today’s objective. Table 13-2 provides bandwidth specifications for devices.2. implementing a LAN. Table 13-1 displays the units you use to describe bandwidth. If you use 100 Mbps switches. maximum bandwidth. Table 13-1 Bandwidth Units Unit Abbreviation Comparison Bits per second bps This is the base unit Kilobits per second kbps 1000 bits per second Megabits per second Mbps 1. Coaxial 10 185 meters 10Base5 Ethernet Thicknet. but the devices and signaling type that you implement in a LAN determine the actual bandwidth. and maximum distance. CCNA 1.2.1–2. Modules 2.

■ Impedance—The resistance of the physical media that can cause a signal to attenuate. Table 13-3 Cable Types Cable Type Use Features Coaxial Thicknet and Thinnet Shielded. ■ Insertion loss—The combination of attenuation and impedance effect on a signal. more expensive than UTP 4. capable of longer distances.2—The following three terms define factors that can affect network signals: ■ Attenuation—The decrease in the strength of a signal as it travels across physical media. CCNA 1.2.5—When you run cable for a LAN.2. Noise that originates from other cables or wires is defined as crosstalk. It would take 8 seconds in perfect conditions to transfer 1 MB of data over a 1 Mbps connection.3–4. yet inexpensive and easy to install Shielded twisted pair (STP) Network installations where noise exists and fiber is less practical IBM-specific cable with two conductors individually covered with grounded foil shielding inside of braided shielding for the entire cable Screened twisted pair (ScTP) Network installations where noise exists and fiber is less practical Category 5 cable with grounded foil shielding. The type of data. single copper wire. 4. it is important to consider sources of noise that can affect your signal. One byte is equal to eight bits. number of users. more expensive than UTP Fiber-optic Long-distance and/or high noise network installations Not affected by electrical noise. A bad connection or cable discontinuity can result in signal echoes causing signal jitter. Table 13-4 outlines different types of crosstalk.1—Your network cabling will likely include one or many of the types of cable outlined in Table 13-3. more expensive and difficult to install than UTP Unshielded twisted pair (UTP) Common network installation cable No shielding. Module 4 4. Pay keen attention to the use of bits in bandwidth measurement and not bytes.22_1587131749_DAY13. and power conditions can affect throughput. devices.2. .2. Noise can be any electrical source that distorts the signal on a cable. You typically use bytes and megabytes to describe file sizes. Do not confuse megabits per second with megabytes.qxd 122 7/28/06 8:56 AM Page 122 31 Days Before Your CCNA Exam The maximum bandwidth may be different from the actual throughput on your network.

configuration. Router to hub Host/server to switch Host/server to hub Rollover cable Terminal to console Pins 1–8 reversed on either end. CCNA 1.2.qxd 7/28/06 8:56 AM Page 123 Day 13 Table 13-4 123 Noise Type Definition Near-end crosstalk (NEXT) Crosstalk from another wire pair on the same end of the link Far-end crosstalk (FEXT) Crosstalk on the far end of the link. straight-through. Switch to hub Hub to hub Router to router Host/server to host Router to host Straight-through cable Router to switch TIA/EIA-568-A on both ends or TIA/EIA-568-B on both ends.5 and 5. or rollover UTP cable. typically a serial port on a host to a console port on a router or switch . Often converted to 9-pin port on a device for serial on one end. less significant due to attenuation Power sum near-end crosstalk (PSNEXT) The effect of NEXT from all wire pairs in a cable The TIA/EIA-568-B standard requires a cable to return acceptable levels for ten cable parameters including NEXT. FEXT.1. and PSNEXT. Module 5 5. Table 13-5 UTP Cabling for Network Devices Cable Used to Connect Description Crossover cable Switch to switch TIA/EIA-568-A on one end and TIA/EIA-568-B on the other end.7—Table 13-5 explains when you would use a crossover.22_1587131749_DAY13.

Your Notes . 1000BaseSX.1–7. Summary UTP now rules the LAN in most situations.qxd 124 7/28/06 8:56 AM Page 124 31 Days Before Your CCNA Exam CCNA 1. Remember that noise can render a network unusable and your data unreadable if you cable your LAN incorrectly. exam #640-801). For longer cable standards. Module 7 7.2. and 10BaseT are legacy 10 Mbps Ethernet standards that you would likely replace with 100 Mbps 100BaseTX Fast Ethernet or 1000BaseTX Gigabit Ethernet.1—10Base5. and 1000BaseLX. 10Base2. The type of cable you use dictates the distance and maximum bandwidth of your link. Second Edition. Combine your knowledge of switching and cabling to answer pages 52–92 in the CCNA Flash Cards and Exam Practice Pack (CCNA SelfStudy.22_1587131749_DAY13.1. Remember that UTP copper cabling can run only 100 meters between devices. you would use 100BaseFX.

Virtual Terminal Protocol (VTP). Module 4 4. ■ Layer 3 switches and routers filter at Layer 3 of the OSI model and divide broadcast domains. You have covered the specifics of these concepts and configurations on Day 14. CCNA 3.” Customize a Switch Configuration to Meet Specified Requirements Static and dynamic virtual LAN (VLAN) assignment.3. consider the following three points when placing and configuring network devices: ■ Bridges and switches divide collision domains and filter at Layer 2. and subinterface configurations all provide the means to customize a switch configuration for your specific network requirements. You can divide this single collision domain with a switch and keep local traffic local because the switch filters based on the MAC address.qxd 7/28/06 8:57 AM Page 125 Day 12 Customize a Switch Configuration to Meet Specified Requirements and Manage System Image and Device Configuration Files (Two Objectives) Today and on Day 11 you cover two objectives in one day. switching modes. “Configure a Switch with VLANs and Interswitch Communication. . ■ Layer 2 switches can also divide broadcast domains with VLANs. those computers all see each other and have to deny or accept every transmission that occurs on that network.2. but you need a router to communicate between VLANs. Routers have enough network knowledge to respond to broadcasts for their connected segments and thus to filter broadcasts.” Today you focus on switch placement and layered model references found in Modules 4 and 5 from CCNA 3.” and you will cover the initial configuration of a switch on Day 11. “Perform an Initial Configuration on a Router and Perform an Initial Configuration on a Switch (Two Objectives). Each port on a bridge or switch is microsegmented into its own collision domain.9 and 4.1–4.2. When you implement a LAN. Not to mention that “31 Days to the CCNA” sounds a lot better than “33 Days to the CCNA. The only time that all devices see a transmission is when a host needs to ask all other hosts for information in the form of a broadcast.23_1587131749_DAY12. The super short switch configuration customization objective fits nicely with the longer system image and configuration file management objective.6—If you connect any number of computers to a hub.

1. Module 3 3. or a disk.9—You can store a configuration file on a TFTP server. How you want a user to connect to the distribution layer will determine the specific configuration of your switches.23_1587131749_DAY12.80 [confirm] y Writing configbackup.qxd 126 7/28/06 8:57 AM Page 126 31 Days Before Your CCNA Exam CCNA 3. Modules 3 and 5 from CCNA 2 provide the information to accomplish these tasks.1.1 to 192.168. use the following commands: copy tftp running-config {select a host or network configuration file} {enter host IP address} {type the name of the configuration file} {type y} .1 Write the file configbackup. a network server.1–5. CCNA 2. you will spend most of your time configuring VLANs and VTP at the access layer of your network.2.2.1 !!!!!! [ok] To restore the file to your router.80 Name of configuration file to write [Router-config]?configbackup. Manage System Image and Device Configuration Files After you configure your network and everything functions properly. make sure you know the IP address of the TFTP server and use the following command: copy running-config tftp {enter host IP address} {type a name for the configuration file} {type y} Example 12-1 Back Up a Configuration to a TFTP Server Router#copy running-config tftp Remote host []?192. To save your router configuration to a TFTP server. Module 5 5.2. it is a great idea to back up your configurations.168.2.6—Although there are beefy switches at the core layer of a network and Layer 3 switches at the distribution layer. As new security threats surface and new software features emerge.8 and 3. you will likely decide to upgrade your network device software.

1. the router first looks for a configuration file in the NVRAM. then looks for a TFTP server that might have the configuration. Once the IOS image is loaded. boot system flash IOS-filename boot system tftp IOS-filename tftp-address boot system rom Example 12-3 Boot System Commands Router(config)#boot system flash myios-image Router(config)#boot system tftp myios-image 192.23_1587131749_DAY12.80 Source filename []? Configbackup.80 Router(config)#boot system rom Router(config)#exit Router#copy running-config startup-config .1.03 secs Router# You can also copy the output of the show run command from your terminal and paste it into a text file to back up a configuration. The commands will be visible in the running-config and startup-config (if saved) and are only used when the register value is set (see Table 12-1).2 and 5. and lastly.1.1 Destination filename [running-config]? running-config Accessing tftp://192. and finally. The order in which you enter the commands will define the order in which the router will use them to find an IOS image. then looks for a TFTP server that could have the IOS image. loads a stripped version of the IOS image from ROM. The purpose of these boot system commands is to override the router’s default configuration register.3—You can define where a router should look for the IOS by entering boot system commands in global configuration mode. if there is no configuration.168. outputs a set of questions to the console to ask the user for configuration parameters.1 !!!!!!!!!!!!!! 752 bytes copied in 8. if there is no other option. The router first looks for the Cisco IOS image in the flash memory. 3. 2. 5.qxd 7/28/06 8:57 AM Page 127 Day 12 Example 12-2 127 Restore a Backup Configuration from a TFTP Server Router#copy tftp running-config Address or name of remote host []? 192.1.168.168. Module 5 5.1—A router starts using the following sequence: 1. The router checks the hardware (POST) and loads the bootstrap code from the read-only memory (ROM). CCNA 2.80/configbackup.1.1.

4—You can also define how a router should boot by editing the configuration register in the NVRAM. The parameters for an IFS management command are as follows: copy location:URL location:URL Example 12-5 Copy a Configuration File with TFTP Using IFS URL Conventions Router#copy tftp://192.1. use the following show command: show running-config 5. 5. This setting will boot the limited ROM version on older platforms.qxd 128 7/28/06 8:57 AM Page 128 31 Days Before Your CCNA Exam 5. and the following command will allow you to change the configuration register: config-register configuration-register-value Example 12-4 Change the Configuration Register Router(config)#config-register 0x2102 Table 12-1 displays the values and descriptions for the configuration register. 0x___2 to 0x___F 0x2142 Looks in the NVRAM for boot system commands.2.23_1587131749_DAY12.1—Cisco IOS release 12. Table 12-1 Configuration Register Values Register Value Example Description 0x___0 0x2100 System enters ROM monitor mode. If there are no commands. The show version command will display the current settings. the system boots the first image in flash. and flash hold the following configuration files: ■ Running configuration—Contained in the RAM ■ Startup configuration—Contained in the NVRAM ■ Cisco IOS image—Contained in flash .168. Use b to boot the system. The IFS allows you to follow a single command convention to manage the file system. 0x___1 0x2101 Boots the first image in flash. NVRAM.1.0 and later releases use the Cisco IOS File System (IFS).1.5—Use the following command to check the configuration register value and the boot image source: show version If you would like to check the boot system commands.80/backup-config system:running-config RAM.

80 Destination filename [c2600-is-mz]? c2600-is-mz-jan06 The following command allows you to restore a Cisco IOS image: copy tftp flash {enter TFTP server IP address} {enter the source filename} {enter or select the destination file name} Example 12-7 Restore an IOS Image from a TFTP Server Router#copy tftp flash Address or name of remote host []?192.6—If your router has a corrupted or missing IOS.1 Release 3) File Format (Relocatable. you can use ROM monitor (ROMMON) mode to restore the image. Not Compressed) Feature Set (Enterprise with Extended Capabilities) Hardware Platform (2600) 5.2.168.5—The following commands back up a Cisco IOS image: copy flash tftp {enter the source filename} {enter TFTP server IP address} {enter or select the destination file name} Example 12-6 Back Up a Cisco IOS Image to a TFTP Server Router#copy flash tftp Source filename []? c2600-is-mz Address or name of remote host []?192.1.bin Version and Release Numbers (Version 12. You should first use the following ROMMON commands to check your Cisco IOS image file and ensure proper boot settings: dir flash: boot flash: image-name .23_1587131749_DAY12.168.2—Figure 12-1 provides an example for the IOS naming convention. Figure 12-1 A Cisco IOS Name Example c2600-js-l_121-3.2.qxd 7/28/06 8:57 AM Page 129 Day 12 129 5.1.2.80 Source filename []? c2600-is-mz-jan06 Destination filename [c2600-is-mz]? c2600-is-mz 5.

The show flash command also shows the image and available flash in the router file system.80 TFTP_FILE=/jan06/c2600-is-mz.7—You can also use ROMMON to restore an image from TFTP using the set command to view your connection variables and then the tftpdnld command to restore the image: set tftpdnld Example 12-9 Restore a Cisco IOS Image Using tftpdnld rommon 1>set IP_ADDRESS=192.bin Once your router is ready to receive.1.168.2.bin rommon 2>tftpdnld If the set command displays incorrect variables.1 TFTP_SERVER=192. 5.8—You can check the current Cisco IOS image and amount of flash on a router with the show version command.23_1587131749_DAY12. 5. you can set the variables by entering the variable name followed by an = and then the desired setting. first use the confreg command to check your connection settings and then use the following xmodem command: xmodem -c image-file-name Example 12-8 Restore a Cisco IOS Image Using xmodem rommon 2>xmodem -c c2600-is-mz.qxd 130 7/28/06 8:57 AM Page 130 31 Days Before Your CCNA Exam If there is in fact an image in the flash and it boots properly with the ROMMON boot flash command. The variables and the filename are case sensitive. . you will need to use your terminal program (HyperTerminal) to send the image that you have saved on your computer. you can use ROMMON and xmodem to copy the IOS through the console connection. you should check your configuration register and boot system commands with these two show commands: show version show startup-config If you do need to restore the image.168.1.10 IP_SUBNET_MASK=255. In ROMMON mode.0 DEFAULT_GATEWAY=192.2.255.1.255.168.

qxd 7/28/06 8:57 AM Page 131 Day 12 131 Summary From the layered design to the exact configuration of each port. exam #640-801). you will encounter numerous switching challenges. Your Notes . review these topics. Pages 350–386 in the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study. Pages 259–274 of the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study. Second Edition. These commands come in handy when you set up your systems and then again when a system has problems. Second Edition. might help you to check your knowledge of switch configuration customization.23_1587131749_DAY12. exam #640-801). Proper configuration and organized Cisco IOS image management are a sign of a prepared network engineer. The software abilities of switches to reconstruct and organize traffic flow provide you with the tools to face such custom challenges.

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Initial router configuration is spread throughout the curriculum. you can use the question mark (?) to see a list of available commands. you cover two objectives in one day. CCNA 2. as on Day 12. The clock command is a great way to try out the question mark (?).24_1587131749_DAY11. A dollar symbol ($) at the beginning of a long line indicates that the line has been scrolled to the left. If the output is more than a page. The command configure terminal from privileged EXEC mode enters you into global configuration mode. From global configuration mode.qxd 7/28/06 8:57 AM Page 133 Day 11 Perform an Initial Configuration on a Router and Perform an Initial Configuration on a Switch (Two Objectives) Today.5—When you initially log in to a router. you can enter a number of interface and specific configuration modes. whereas typing end or using the key combination Ctrl-Z places you back at the privileged EXEC mode. If there is an error in a command. . but Modules 2 and 3 from CCNA 2 focus on the key points necessary. You can also type a command followed by a question mark (?) to see possible ways to complete the command. The initial configuration of a router and initial configuration of a switch represent the common tasks that you will perform when you take a Cisco networking device out of its box and add it to your network. 2. the caret symbol (^) will note where the command may have an error. User EXEC mode allows you to execute commands that show the status of a router.2.6 and 2. Typing the command exit takes you back one mode at a time.2. Perform an Initial Configuration on a Router Day 11 provides a quick overview of the housekeeping commands required to organize and begin setup on routers and switches.2.7—While logged in to the router. pressing the Spacebar enables you to view the next screen. Module 2 2. the first command mode you enter is user EXEC mode. and the command prompt will change to a number symbol (#). You can type enable to enter privileged EXEC mode. Table 11-1 displays the editing commands that you may sometimes use and that you will always need to know for the CCNA exam.

2.qxd 134 7/28/06 8:57 AM Page 134 31 Days Before Your CCNA Exam Table 11-1 Cisco IOS Editing Keys and Commands Keystroke or Command Definition Tab Automatically complete a command Ctrl-P or Up Arrow Repeat previously typed command Ctrl-A Move to the beginning of a command line Esc-B Move back one word Ctrl-B or Left Arrow Move back one character Ctrl-E Move to the end of the command line Ctrl-F or Right Arrow Move forward one character Esc-F Move forward one word Ctrl-Z Exit configuration mode terminal no editing Turn off advanced editing mode 2.2.8—Table 11-2 displays the keys and commands related to the Cisco IOS command history.1–3.7—Example 11-1 shows a sample initial configuration on a router (does not include a routing protocol). Module 3 3. Table 11-2 Cisco IOS Command History Keys and Commands Keystroke or Command Definition Ctrl-P or Up Arrow Repeat the last command Ctrl-N or Down Arrow Repeat the most recent command in the history buffer show history Display the command buffer terminal history size number Set the history buffer size terminal no editing Turn off advanced editing terminal editing Enable advanced editing CCNA 2.24_1587131749_DAY11.1. .

2. add both security and better organization to your network by completing the initial configuration of a switch.1 255.qxd 7/28/06 8:57 AM Page 135 Day 11 Example 11-1 135 Router Initial Configuration Example Router>enable Router#configure terminal Router(config)#hostname RouterA RouterA(config)#banner motd # Enter TEXT message.2.1. End with the character ‘#’. Module 6 6. You can.0 RouterA(config-if)#description Main Office LAN RouterA(config-if)#no shutdown RouterA(config-if)#no shutdown RouterA(config-if)#exit RouterA(config)#ip host RouterA 192.24_1587131749_DAY11. CCNA 3.255.255. covered in Module 6 from CCNA 3.1 and 6. Welcome to RouterA # RouterA(config)#enable secret class RouterA(config)#line console 0 RouterA(config-line)#password cisco RouterA(config-line)#login RouterA(config-line)#exit RouterA(config)#line vty 0 4 RouterA(config-line)#password cisco RouterA(config-line)#login RouterA(config-line)#exit RouterA(config)#interface fa0/0 RouterA(config-if)#ip address 192.dat erase startup-config reload .2—By default. You can assign an IP address to a virtual interface in VLAN 1 for remote management.1 RouterA(config)#exit RouterA#copy running-config startup-config Perform an Initial Configuration on a Switch Many switches work perfectly on a small network without any additional configuration. a switch has only VLAN 1 and no IP address. VLAN 1 is also called the management VLAN.168.1. To completely clear a switch. however.168. use the following commands: delete flash:vlan.

1.1 6.1.255.168.255.1 SwitchA(config)#copy running-config startup-config Example 11-4 provides the commands to implement a basic switch configuration on a Catalyst 1900.24_1587131749_DAY11.168.168.3—A switch maintains a MAC address table that you can view and clear with the following commands: show mac-address table clear mac-address table .0 SwitchA(config-if)#no shutdown SwitchA(config-if)#exit SwitchA(config)#ip default-gateway 192. Example 11-3 A Basic Switch Configuration on a Catalyst 2950 Switch>enable Switch#configure terminal Switch(config)#hostname SwitchA SwitchA(config)#line con 0 SwitchA(config-line)#password cisco SwitchA(config-line)#login SwitchA(config-line)#line vty 0 15 SwitchA(config-line)#password cisco SwitchA(config-line)#login SwitchA(config-line)#exit SwitchA(config)#enable secret class SwitchA(config)#interface VLAN 1 SwitchA(config-if)#ip address 192.qxd 136 7/28/06 8:57 AM Page 136 31 Days Before Your CCNA Exam Example 11-2 Clearing a Switch Configuration Switch#delete flash:vlan.168.0 SwitchA(config)#ip default-gateway 192.dat Switch#erase startup-config Switch#reload Example 11-3 provides the commands to implement a basic switch configuration on a Catalyst 2950.255.2 255.2.1.2 255.255.1. Example 11-4 A Basic Switch Configuration on a Catalyst 1900 Switch>enable Switch#configure terminal Switch(config)#hostname SwitchA SwitchA(config)#enable secret class SwitchA(config)#ip address 192.

You should also be able to move the switch operating system to a TFTP server as a backup.bin The commands in Example 11-8 allow you to back up your switch operating system on a Cisco Catalyst 2900 switch.EA1.2.2. you can allow only one MAC address to be used per port with the following commands to enable port security: switchport mode access switchport port-security switchport port-security maximum {maximum-number-of-MACs-per-port} switchport port-security violation {restrict | shutdown} Example 11-6 Port Security Configuration Switch(config)#interface fastethernet 0/2 Switch(config-if)#switchport mode access Switch(config-if)#switchport port-security Switch(config-if)#switchport port-security maximum 1 Switch(config-if)#switchport port-security violation shutdown Port security is a good alternative to managing all MAC addresses on a network with static configuration unless you have no scruples and you are getting paid by the hour.121-13.EA1jan06.2. 6.2233.EA1. The commands in Example 11-7 allow you to back up your switch operating system on a Cisco Catalyst 2950 switch.80 Destination filename [c2950-i6q4l2-mz.bin]? c2950-i6q4l2-mz.1.24_1587131749_DAY11.7—Make sure that any new switch you are adding to a network has a basic config- uration similar to the ones in section 6.2.2 of the CCNA 3 course.2.4455 interface FastEthernet 0/3 vlan 1 Use the command no in front of Example 11-5 to remove the static MAC address configuration. . Example 11-7 Back Up the Switch Software to a TFTP Server on a Cisco Catalyst 2950 Switch Switch#copy flash tftp Source filename []? c2950-i6q4l2-mz.6 and 6.168.bin Address or name of remote host []? 192.qxd 7/28/06 8:57 AM Page 137 Day 11 137 6.121-13.121-13.4—The following command assigns a static MAC address to a port on a switch: mac-address-table static host-mac-address interface interface vlan vlan Example 11-5 Static MAC Address Configuration Switch(config)#mac-address-table static 0011. 6.5—If you are concerned about users attempting to falsify Layer 2 information (MAC spoof- ing) on your network.

hostnames.bin]? [press enter] A Catalyst 1900 switch requires you to use the configuration menu to download a new software image to your switch.bin Destination filename [c2950-i6q4l2-mz.121-13. Example 11-9 Restore the Switch Software from a TFTP Server on a Cisco Catalyst 2950 or 2900 Switch Switch#copy tftp flash Address or name of remote host []? 192. Second Edition.121-13. Once you have skimmed through the process to add passwords.EA1.168. Summary Configuring a hostname and initial passwords on a router should be as common to you as washing the dishes.EA1. You can also quiz yourself with pages 211–238 from the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study. The Catalyst 1900 is not able to upload an image.bin]? [press enter] Destination IP address or hostname []? 192.168. .EA1. pages 205–210. exam #640-801).121-13.1.bin tftp Source filename [c2950-i6q4l2-mz.80 Source filename []? c2950-i6q4l2-mz. exam #640-801).EA1. Today.121-13.bin]? c2950-i6q4l2-mz.80 Destination filename [c2950-i6q4l2-mz.bin Use the commands shown in Example 11-9 to restore the switch operating system.EA1.121-13. The initial setup of a router provides you with a quick warm-up for the advanced commands that are not as intuitive. you also covered slightly more than the initial configuration of a switch. You can also get a quick quiz fix from the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study.24_1587131749_DAY11.121-13. you should practice on a simulator or in a lab on different models.EA1jan06. and addressing to a switch.qxd 138 7/28/06 8:57 AM Page 138 31 Days Before Your CCNA Exam Example 11-8 Back Up the Switch Software to a TFTP Server on a Cisco Catalyst 2900 Switch Switch#copy flash:c2950-i6q4l2-mz. Second Edition.1.

qxd 7/28/06 8:57 AM Page 139 Day 11 Your Notes 139 .24_1587131749_DAY11.

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255 Router(config)#access-list 25 permit any Router(config)#int fa0/0 Router(config-if)#ip access-group 25 in The term any represents a source of 0.” discussed ACL design and theory. CCNA 2. For this final countdown to the CCNA.0 and source-wildcard of 255. “Troubleshoot an Access List.1. “Evaluate Rules for Packet Control.255.1.0. Table 10-1 Access Control List Number Specifications Protocol Range Standard IP 1–99. 1300–1999 Extended IP 100–199.0.0 0.0.255. Today provides the third installment of the access control list (ACL) quartet in this book.qxd 7/28/06 8:57 AM Page 141 Day 10 Implement an Access List Ten days to the exam. All of these days review the information covered in Module 11 of CCNA 2. You can only assign . and Day 3. Day 25.0. Today you review ACL configuration.255. Module 11 11.” and Day 19.168.3—Table 10-1 defines the range of numbers that you can use to define ACLs.” briefly covers ACL troubleshooting. You should also keep in mind that a default deny any exists at the end of all access lists. you will encounter short chapters that will allow you to review quickly and still have time for hands-on practice and practice exams. “Develop an Access List to Meet User Specifications. 2000–2699 AppleTalk 600–699 IPX 800–899 Extended IPX 900–999 IPX Service Advertising Protocol 1000–1099 You use the following commands to configure a standard access list and then to apply that access list to an interface: access-list ACL-number {deny | permit} source-address wildcard-mask ip access-group ACL-number {in | out} Example 10-1 Standard Access Control List Router(config)#access-list 25 deny 192.25_1587131749_DAY10.

2.168.23 eq www Router(config)#access-list 101 permit tcp any any Router(config)#int fa0/0 Router(config-if)#ip access-group 101 in The term host in an access list substitutes the wildcard mask 0.25_1587131749_DAY10.168. destination address.0.1–11. The following examples of extended ACLs display these additional filtering options: access-list ACL-number {deny | permit} protocol source wildcard destination wildcard operator port ip access-group ACL-number {in | out} Example 10-3 Extended Access Control List Filtering a Web Server Router(config)#access-list 101 deny tcp any host 192. you can use www or the port number 80 to represent the Layer 4 HTTP protocol.23 eq www Router(config-ext-nacl)#permit tcp any any Router(config-ext-nacl)#exit Router(config)#int fa0/0 Router(config-if)#ip access-group filterweb in .0.0 to match just one address.0. access-list ACL-number {deny | permit} protocol source wildcard-mask destination wildcard-mask ip access-group ACL-number {in | out} Example 10-2 Extended Access Control List Router(config)#access-list 101 deny tcp 192.3—While standard access lists filter only the source IP address.0.2.255 Router(config)#access-list 101 permit tcp any any Router(config)#int fa0/0 Router(config-if)#ip access-group 101 in 11.255 192. You can use the following commands to configure an extended access list. A named access list allows you to configure an alphanumeric name for an ACL and bypass the limits of numbering.0.0. an extended ACL can filter the source address.5.1.168. The following commands allow you to configure a named ACL: access-list {extended | standard} name {deny | permit} protocol source wildcard destination wildcard operator port ip access-group acl-name {in | out} Example 10-4 Named Access Control List Filtering a Web Server Router(config)#access-list extended filterweb Router(config-ext-nacl)#deny tcp any host 192.qxd 142 7/28/06 8:57 AM Page 142 31 Days Before Your CCNA Exam one access list per protocol per direction per interface. and the Layer 4 protocol.1. In Example 10-3.0 0.1.0 0.168.

you need to design. The following commands allow you to restrict vty access: access-list ACL-number {deny | permit} source-address wildcard-mask access-class ACL-number {in | out} Example 10-5 Restrict vty with an Access Control List Router(config)#access-list 5 permit host 192. document.2. .168.25_1587131749_DAY10. remember to put an extended ACL as close to the source of the traffic you are filtering as possible. Second Edition.30 Router(config)#line vty 0 4 Router(config-line)#access-class 5 in Summary To truly perform well on the access list portion of the CCNA exam.1. and troubleshoot ACLs on a functioning or simulated network. It would also help to read through pages 456–476 in the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study.2. exam #640-801). implement.6—You can restrict vty access using access lists. You should put a standard ACL as close to the destination of the traffic you are filtering as possible. 11.qxd 7/28/06 8:57 AM Page 143 Day 10 143 11. You should apply the same restrictions to all vty lines. The access-class command replaces the access-group command when configuring access lists for vty lines. Spend some time in the Cisco IOS software at your lab or with a simulator to memorize the commands covered in this chapter.4—As a quick reminder from Day 25.

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Module 1 from CCNA 2 and Modules 3. but they act as WAN devices as well and can require additional configuration to facilitate WAN connectivity. routers choose the best path for Layer 3 packets across a network. and Frame Relay. Module 3 3. Integrated Services Digital Network (ISDN).1. compression.4—On a LAN.1 and 3. and load balancing: encapsulation ppp compress {predictor | stac} ppp quality {1 to 100 as a percentage} ppp multilink Example 9-1 Enabling PPP Router(config)#interface serial 0/0 Router(config-if)#encapsulation ppp Router(config-if)#compress predictor Router(config-if)#ppp quality 50 Router(config-if)#ppp multilink 3. error detection. CCNA 4.3.3—Use the following commands to set up PPP authentication: username name password secret-password encapsulation ppp ppp authentication {chap | chap pap | pap chap | pap} ppp pap sent-username username password password . “Evaluate Key Characteristics of WANs. and 5 from CCNA 4 discuss WAN protocol configuration.26_1587131749_DAY09. 4. and multilink features in PPP.2—You can configure authentication. On a WAN. routers also function at Layer 3 to direct packets. link quality.3. dial-on-demand routing (DDR).3.” you evaluated and selected routing protocols. Today you review the configurations of the WAN technologies Point-to-Point Protocol (PPP). Module 1 1. CCNA 2. “Develop an Access List to Meet User Specifications.qxd 7/28/06 8:57 AM Page 145 Day 9 Implement Simple WAN Protocols On Day 24. The following commands enable PPP encapsulation and configure compression.” and Day 19.

2. Module 4 4.2—To configure ISDN PRI.qxd 146 7/28/06 8:57 AM Page 146 31 Days Before Your CCNA Exam Example 9-2 PPP Authentication Router(config)#username cisco password class Router(config)#interface serial 0/0 Router(config-if)#encapsulation ppp Router(config-if)#ppp authentication chap pap Router(config-if)#ppp pap sent-username cisco password class 3. or you can specify the switch type for specific interfaces.3.1—You can configure ISDN to use the same switch type for all interfaces on the router.2. The following commands allow you to set these parameters for an ISDN PRI T1: controller t1 framing {sf | esf} linecode {ami | b8zs | hdb3} pri-group timeslots range interface serial {slot/port: | unit:} {23 | 15} isdn switch-type switch-type . you specify the switch type as well as the controller. The following commands will configure ISDN to use the same switch type for all interfaces using BRI: isdn switch-type switch-type isdn spid{number} spid-number local-dial-number encapsulation ppp Example 9-3 ISDN BRI Configuration Router(config)#isdn switch-type basic-ni Router(config)#interface bri0/0 Router(config-if)#isdn spid1 51086750000001 8675000 Router(config-if)#isdn spid2 51086750010001 8675001 4.26_1587131749_DAY09. and speed. group timeslot. line coding. framing type.4—You can verify the PPP encapsulation configuration with the following command: show interfaces show interfaces serial CCNA 4.

and PPP configuration: dialer-list number protocol protocol {permit | deny | list [access-list-number]} interface interface . If the link comes up due to interesting traffic.3—The following commands allow you to verify your ISDN configuration: show isdn status show isdn active show dialer show interface 4. You can define a dialer-list on a Cisco router that tells the router what traffic should cause it to bring up a DDR link.1—Dial-on-demand routing (DDR) defines interesting traffic as network activity that causes a router to connect to a network.2. all traffic can pass over the link while it is active. DDR configurations do not filter traffic.2–4. Access lists can also help you to better define interesting traffic. an access list.26_1587131749_DAY09.3. you need to use static routes to lower the cost of the route.qxd 7/28/06 8:57 AM Page 147 Day 9 Example 9-4 147 ISDN PRI T1 Configuration Router(config)#controller t1 1/0 Router(config-controller)#framing esf Router(config-controller)#linecode b8zs Router(config-controller)#pri-group timeslots 1-24 Router(config-controller)#interface serial3/0:23 Router(config-if)#isdn switch-type primary-5ess Router(config-if)#no cdp enable You would use the following commands to configure an ISDN PRI E1: controller e1 framing {crc4 | no-crc4} linecode {ami | b8zs | hdb3} pri-group timeslots range interface serial {slot/port: | unit:} {23 | 15} isdn switch-type switch-type Example 9-5 ISDN PRI E1 Configuration Router(config)#controller e1 1/0 Router(config-controller)#framing crc4 Router(config-controller)#linecode hdb3 Router(config-controller)#pri-group timeslots 1-31 Router(config-controller)#interface serial3/0:15 Router(config-if)#isdn switch-type primary-net5 Router(config-if)#no cdp enable 4.3.5—To configure DDR.3. 4. You would use the following commands to create a basic configuration for legacy DDR including a static route.

you can do the following: ■ Use different encapsulations and access lists ■ Set minimum and maximum calls ■ Enable and disable features You can add configurations to virtual dialer interfaces and then apply them to a pool of physical interfaces.168.255.168.0 192.0 192.3.26_1587131749_DAY09.1.168.255.168.1 name RouterB 8675309 4. If you use dialer profiles with DDR.0 255.3.3.168.1.1.255.2 RouterA(config)#dialer-list 1 protocol ip list 101 RouterA(config)#access-list 101 deny tcp any any eq ftp RouterA(config)#access-list 101 deny tcp any any eq telnet RouterA(config)#access-list 101 permit ip any any RouterA(config)#username RouterB password class RouterA(config)#interface bri0/0 RouterA(config-if)#dialer-group 1 RouterA(config-if)#encapsulation ppp RouterA(config-if)#ppp authentication chap RouterA(config-if)#dialer idle-timeout 180 RouterA(config-if)#dialer map 192.2 RouterA(config)#dialer-list 1 protocol ip permit RouterA(config)#username RouterB password class RouterA(config)#interface bri0/0 RouterA(config-if)#dialer-group 1 RouterA(config-if)#encapsulation ppp RouterA(config-if)#ppp authentication chap RouterA(config-if)#dialer idle-timeout 180 RouterA(config-if)#dialer map 192.1 name RouterB 8675309 Example 9-7 Legacy DDR Configuration with Access Lists RouterA(config)#ip route 192.168.3. router interfaces can apply the configuration on a per-call basis.qxd 148 7/28/06 8:57 AM Page 148 31 Days Before Your CCNA Exam dialer-group number dialer idle-timeout seconds-after-last-traffic dialer map ip next-hop name next-hop-hostname dial-number Example 9-6 Legacy DDR Configuration Without Access Lists RouterA(config)#ip route 192.1.6 and 4. With dialer profiles. The following commands allow you to configure dialer profiles: dialer-list number protocol protocol {permit | deny | list [access-list-number]} interface dialer virtual-interface-number dialer-group number dialer remote name next-hop-hostname .255.0 255.7—Legacy DDR applies the configuration to a specific interface.

0 RouterA(config-if)#dialer-group 1 RouterA(config-if)#dialer remote name RouterB RouterA(config-if)#dialer string 8675309 RouterA(config-if)#dialer pool 1 RouterA(config-if)#interface bri0/0 RouterA(config-if)#encapsulation ppp RouterA(config-if)#ppp authentication chap RouterA(config-if)#dialer idle-timeout 180 RouterA(config-if)#dialer pool-member 1 priority 50 4.168. and the default encapsulation type is Cisco HDLC.1.168. Module 5 5.qxd 7/28/06 8:57 AM Page 149 Day 9 149 dialer string dial-number dialer-pool number dialer idle-timeout seconds-after-last-traffic dialer pool-member number priority priority Example 9-8 DDR Profile Configuration Without Access Lists RouterA(config)#ip route 192.5—You can configure your router for Frame Relay on a serial interface.255.0 192.8—The following commands allow you to verify your DDR configuration: show dialer show isdn active show isdn status CCNA 4.2 RouterA(config)#dialer-list 1 protocol ip permit RouterA(config)#username RouterB password class RouterA(config)#interface dialer 0 RouterA(config-if)#ip address 192. you can also use the Internet Engineering Task Force (IETF) standard encapsulation. Although many non Cisco routers support this encapsulation.1.168.255.3.255. The following commands configure a basic Frame Relay permanent virtual circuit (PVC): encapsulation frame-relay {cisco | ietf} frame-relay map protocol protocol-address dlci broadcast .26_1587131749_DAY09.1 255.3.1–5.0 255.2.255.2.

168.2 151 ietf broadcast RouterA(config-if)#description PVC to Portland.0.1.168.255. DLCI 130 RouterA(config-if)#ip address 192.1 255.168.255. DLCI 151 For multiple connections across a Frame Relay network. DLCI 131 RouterA(config-if)#ip address 192.168.1 255.130 point-to-point RouterA(config-if)#description PVC to Boise.0 RouterA(config-if)#frame-relay interface-dlci 130 RouterA(config-if)#interface serial 0. you can configure subinterfaces.2.0 RouterA(config-if)#no shutdown RouterA(config-if)#no keepalive RouterA(config-if)#frame-relay map ip 192.26_1587131749_DAY09.255. The subinterfaces can exist in their own subnet as point-to-point links.131 point-to-point RouterA(config-if)#description PVC to Seattle.1 255.qxd 150 7/28/06 8:57 AM Page 150 31 Days Before Your CCNA Exam Example 9-9 DTE Frame Relay PVC Configuration Without a Frame Relay Switch (No Local Management Interface [LMI]) RouterA(config)#interface serial 0 RouterA(config-if)#encapsulation frame-relay ietf RouterA(config-if)#ip address 192.255.2.255.0.6—The following commands allow you to verify your Frame Relay configuration: show interfaces show frame-relay lmi show frame-relay pvc dlci-number show frame-relay map . or you can configure the subinterfaces to share a single subnet as multipoint links.0 RouterA(config-if)#frame-relay interface-dlci 131 5. The following example shows a Frame Relay configuration with subinterfaces: encapsulation frame-relay {cisco | ietf} frame-relay lmi-type {ansi | cisco | q933a} interface serial {subinterface-number} {point-to-point | multipoint} frame-relay interface-dlci DLCI-number Example 9-10 Frame Relay Configuration with Subinterfaces RouterA(config)#interface serial 0 RouterA(config-if)#encapsulation frame-relay ietf RouterA(config-if)#frame-relay lmi-type ansi RouterA(config-if)#no shutdown RouterA(config-if)#interface serial 0.255.

. ISDN. You can also quickly test your knowledge with pages 511–574 in the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study. and Frame Relay configurations allow you to create complete networks that can span wide geographic areas.26_1587131749_DAY09. PPP. it is a good idea to at least work through simulations and practice the commands for the CCNA exam. Second Edition. DDR.qxd 7/28/06 8:57 AM Page 151 Day 9 151 Summary Although it is more difficult to find hands-on practice for WAN configurations. exam #640-801).

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27_1587131749_Pt4.qxd 7/28/06 8:57 AM Page 153 Part IV 8–1 Day(s) Before the Exam— Troubleshooting Day 8: Utilize the OSI Model as a Guide for Systematic Troubleshooting Day 7: Perform LAN and VLAN Troubleshooting Day 6: Troubleshoot Routing Protocols Day 5: Troubleshoot IP Addressing and Host Configuration Day 4: Troubleshoot a Device as Part of a Working Network Day 3: Troubleshoot an Access List Day 2: Perform Simple WAN Troubleshooting Day 1: Key Points From Each Day for Relaxed Skimming .

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Day 8
Utilize the OSI Model as a Guide for
Systematic Troubleshooting
The OSI seven-layer model allows you to chew a network into smaller, more digestible chunks.
This division also provides a great framework for troubleshooting. OSI model–related troubleshooting is discussed in Module 2 from CCNA 1; Modules 8, 9, and 10 from CCNA 2; and
Module 6 from CCNA 4.

CCNA 1, Module 2
2.3.3—Table 8-1 provides a quick review of the OSI seven-layer model.
Table 8-1

The Open System Interconnection Seven-Layer Model

Layer Number

Layer Name

Protocol Data Unit

Devices

7

Application

Data

N/A

6

Presentation

Data

N/A

5

Session

Data

N/A

4

Transport

Segment

N/A

3

Network

Packet

Router

2

Data link

Frame

Bridge, Switch

1

Physical

Bit

Hub, Repeater

CCNA 2, Module 8
8.1.5—You can test connectivity at OSI Layer 3 with the ping command. The ping command
issues an Internet Control Message Protocol (ICMP) echo request and then receives an echo reply
to verify connectivity. You typically issue the ping command followed by the IP address of the
destination device.

CCNA 2, Module 9
9.2.1—The OSI model provides an excellent structure for network troubleshooting. You can begin
at Layer 1 and work up to Layer 7 until you discover, solve, and document the issue.

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9.2.2—The following steps outline a typical troubleshooting model:
Step 1

Collect information and analyze the symptoms of the problem.

Step 2

Localize the problem to a segment of the network, device, or user.

Step 3

Isolate the problem to a specific piece of hardware or software.

Step 4

Correct the problem.

Step 5

Verify that the problem has been corrected.

Step 6

Document the problem.

Steps 2 through 4 can be incorporated with the OSI model by checking, fixing, and verifying each
layer, starting with Layer 1.
9.2.3–9.2.5—Problems at the first three layers of the OSI model are characterized by the following issues:

Physical layer (1)—Problems with cables and power. Cables in the wrong port, improperly
attached cables, and incorrect cable types are Layer 1 issues. Data terminal equipment (DTE)
and data communications equipment (DCE) cable problems or transceiver issues also qualify
as Layer 1 problems. Check all indicator LEDs and power LEDs before any other troubleshooting.

Data link layer (2)—Improper or missing configurations for clock rate and encapsulation
classify as Layer 2 issues. Serial and Ethernet configuration issues occur at Layer 2. Problems
with a NIC can also be considered Layer 2 issues.

Network layer (3)—IP addressing and routing protocol configuration issues occur at Layer 3.
Incorrect subnet masks also classify as Layer 3 issues. Problems identified with the ping
command (after testing Layers 1 and 2) are often Layer 3 issues. If you ping another device
and receive the ICMP destination unreachable message, the packet was not delivered. You can
use an extended ping command by typing ping without an IP address or hostname.

9.2.5—Telnet tests all seven layers of the OSI model. If you have a password configured for a vty

on your routers and you can telnet between them, all seven layers of the OSI model function on
your network. If you can ping a router but you cannot telnet to the router, you should first check
your vty setup.
9.2.6—If you issue the show interfaces command, Layer 1 issues are indicated by the line status.

If a router responds that the interface is down, it indicates that there is an issue with the cable or a
connected device.
9.3.1–9.3.3—The show interfaces command can also provide you with information about Layer

2 problems. If the show interface command for a serial interface returns that the serial 0/0 is
administratively down, you have not enabled the interface. A message that the interface is up but
the line protocol is down indicates a Layer 2 issue, such as keepalives on the link or improper
encapsulation. To verify connectivity at Layer 2 with Cisco devices, you can also use Cisco
Discovery Protocol (CDP). You review CDP on Day 7, “Perform LAN and VLAN
Troubleshooting.”

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CCNA 2, Module 10
10.1.3—A less obvious connectivity issue can occur at Layer 4 of the OSI model. The three-way

handshake that occurs at the transport layer is susceptible to a denial of service (DoS) attack carried out with continuous synchronization flooding. You can use software to monitor and detect
DoS attacks.

CCNA 4, Module 6
6.2.2 and 6.2.4—The OSI group also directed the development of a network management

model. This model deals with network management applications that operate at the transport and
application layers and often use Simple Network Management Protocol (SNMP) on Layer 4 port
161 and 162 User Datagram Protocol (UDP). The network information gathered by a management
information base (MIB) can provide valuable network statistics for troubleshooting and recognizing issues with OSI Layers 4 through 7.

Summary
A clear understanding of the seven layers of the OSI model aids your ability to describe a network
and to describe, document, and fix network issues. Although you covered them on Day 30,
“Describe the Spanning Tree Process,” it might not be a bad idea to return to pages 13–34 of the
CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study, exam #640-801), Second Edition
for some good old OSI review.

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Your Notes

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The Cisco Networking Academy Program covers methods for troubleshooting LANs and VLANs in Modules 4. This means you can properly connect and power up two Cisco devices and expect that they will exchange CDP advertisements over Layer 2 once you have enabled the interfaces with the no shutdown command and configured a clock rate for interfaces with a data communications equipment (DCE) cable attached. The command clear cdp counters clears gathered CDP information.1. CDP gives you that extra layer of troubleshooting when ping and telnet yield unsatisfactory results. Module 4 4.1. and 9 from CCNA 2 and Module 8 from CCNA 3. you can use the command cdp enable to start CDP on a specific interface.29_1587131749_DAY07. 4. The following commands will display information about CDP and CDP-enabled devices: show cdp traffic show cdp show cdp neighbors show cdp neighbors detail . CCNA 2. This makes your job a little easier when troubleshooting connectivity issues.2—The show cdp neighbors command reveals the following information about directly connected neighboring Cisco devices: ■ Device ID ■ Local interface ■ Holdtime ■ Capacity ■ Platform 4.1.3 and 4.1—All Cisco devices have CDP turned on by default. CDP version 2 (CDPv2) is the protocol running on devices with Cisco IOS Software Release 12.1.4—If you enter the command cdp run at the privileged EXEC prompt. CDP uses the Subnetwork Access Protocol (SNAP) to communicate over a network with directly connected neighbors. It is important to remember that the show cdp command shows information about the protocol only and that show cdp neighbors reveals information about connected devices. you enable CDP on all interfaces on a device.qxd 7/28/06 8:58 AM Page 159 Day 7 Perform LAN and VLAN Troubleshooting Cisco Discovery Protocol (CDP) is a great troubleshooting tool with Cisco devices. If you enter into interface configuration mode. CDP is media and protocol independent and operates at the data link layer of the OSI model.0(3)T or later. 5.

including Layer 3 configurations of neighboring devices.1. Module 9 9.2.2. troubleshoot.3.1. 4. In HyperTerminal. “Customize a Switch Configuration to Meet Specified Requirements and Manage System Image and Device Configuration Files (Two Objectives).29_1587131749_DAY07.5—The following two commands will turn off CDP globally or on a specific interface: no cdp run no cdp enable 4.3—As mentioned in Module 4 of CCNA 2.3 and 5. Module 5 5. the show cdp neighbors detail command is a very valuable tool.qxd 160 7/28/06 8:58 AM Page 160 31 Days Before Your CCNA Exam You can use the show cdp neighbors detail command to reveal the most information. . This command displays device details such as the following items: ■ Active interfaces ■ Port ID ■ Device type ■ Cisco IOS version ■ IP address of a neighboring device’s interface You have to bring the interface up with the no shutdown command and set a clock rate (if necessary) in order to receive CDP advertisements.4—On Day 12. and monitor CDP activity on your Cisco device: clear cdp table show debugging debug cdp adjacency debug cdp events debug cdp ip debug cdp packets cdp timer cdp holdtime CCNA 2.” you reviewed the backup of configuration files using a TFTP server discussed in Module 3 from CCNA 2. you can use the menu items Transfer > Capture Text and then Transfer > Send Text to capture and then later place a configuration on a router.6—The following commands allow you to view. CCNA 2. Module 5 from CCNA 2 repeats this information and provides more detail on the use of HyperTerminal to capture a configuration.

exam #640-801).2—VLANs have become common in networks due to their ability to logically divide and organize traffic flow. you can then check other parameters with the following show commands. Module 8 8. Step 6 Look at traffic patterns and identify possible bottlenecks. and show commands outlined today. Step 2 Pick one switch as a starting point and work outward. Step 4 Check Layer 2. If STP is running properly.qxd 7/28/06 8:58 AM Page 161 Day 7 161 CCNA 3.29_1587131749_DAY07.3–8. might also be helpful as you prepare for the CCNA exam. . Second Edition. you can check the router interfaces and the Cisco IOS software trunking compatibility with the following commands: show interfaces interface trunk show interfaces interface switchport show interface status show running-config show version Summary If you use the OSI model as a reference and the cdp. Step 5 Check VLANs that span multiple switches. Pages 240–258 and 383–386 in the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study.3. You can use the following steps to troubleshoot VLANs: Step 1 Check LEDs and cables. Step 3 Check Layer 1. you have a great toolkit to solve LAN and VLAN issues. protocols.1 and 8. which allow you to look for errors in VLAN setup.5—If Spanning Tree Protocol (STP) is not functioning properly. and naming: show vlan show spanning-tree debug sw-vlan packets If you are having trouble establishing a trunk connection between a router and a switch.3.3.3. 8. your network could be experiencing broadcast storms. debug.

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show ip protocols Displays routing protocol information. Table 6-1 Routing Table–Related Troubleshooting Command Examples Definition show ip route show ip route rip Displays routing table information. show ip protocols .168. show ip route igrp show ip route static show ip route 192. The second example also defines a default route with a static route.1. CCNA 2.7 and 7.0.1–9. and 3 from CCNA 3.0/0 ip route 0.0.0 Sets a default route.0 ip route 0.0 192. The show commands can provide a valuable snapshot.0.0 0.168.9—Table 6-1 provides a definition and examples of troubleshooting and configuration commands that pertain to the routing table.qxd 7/28/06 8:58 AM Page 163 Day 6 Troubleshoot Routing Protocols An advantage to using the command-line interface (CLI) of Cisco IOS software is your ability to use show and debug commands to obtain information about your network.0.3.0.0.1. The Cisco Networking Academy Program curriculum covers routing protocol–related troubleshooting commands in Modules 7 and 9 from CCNA 2 and in Modules 1. as a specific example: show interface show running-config show ip protocols show ip route debug ip igrp events debug ip igrp transactions ping traceroute CCNA 2. 2.1. including the Interior Gateway Routing Protocol (IGRP). show ip rip database show ip rip database Displays RIP updates.5. Module 9 9.168. Module 7 7.0 ip default-network ip default-network 192.8—The following commands allow you to verify and troubleshoot routing proto- cols.1. whereas debug commands can display real-time routing protocol activity.30_1587131749_DAY06.3.

3. 0 for an outgoing interface EIGRP summary route 5 eBGP 20 EIGRP (internal) 90 IGRP 100 OSPF 110 IS-IS 115 RIP 120 EIGRP (external) 170 iBGP 200 CCNA 3.qxd 164 7/28/06 8:58 AM Page 164 31 Days Before Your CCNA Exam A quick look at the routing table can help you to determine which route has the lowest administrative distance.30_1587131749_DAY06. ■ Make sure that your interfaces are not on different network types. Table 6-2 Default Administrative Distances Routing Protocol Default Administrative Distance Directly connected 0 Static 1 for a next hop IP address. ■ Make sure that you do not have different hello and dead interval timers. Notice that the pattern of troubleshooting commands is similar for each protocol.7—If you have configured Open Shortest Path First (OSPF) and the routers are not communi- cating.5 and 1.6—The following commands allow you to verify and troubleshoot the Routing Information Protocol (RIP).2. . show ip protocols show ip route show ip interface brief show running-config debug ip rip It is also useful to know that the undebug all or no debug all commands turn off all debugging. CCNA 3. you should consider the following possibilities: ■ Make sure that the neighbors are sending hellos. Module 1 1. Default administrative distances for common routing protocols are listed in Table 6-2.2. Module 2 2.

EIGRP. CCNA 3.3.30_1587131749_DAY06. ■ Make sure that you have issued the no shutdown command for each interface. consider the following points: ■ Clearly define the problem and gather all the related facts. Table 6-3 Troubleshooting Commands for Routing Protocols Routing Protocol Troubleshooting Commands RIP show running-config show ip protocols show ip route debug ip rip IGRP show running-config show ip protocols show ip route debug ip igrp debug ip igrp events EIGRP show running-config show ip protocols show ip eigrp neighbors OSPF show running-config show ip protocols show ip route show ip ospf neighbor debug ip ospf events debug ip ospf packet 165 . ■ Make sure that the addressing is set up correctly. including wildcard masks. ■ Document the fix. Module 3 3. change one thing at a time until you can isolate the problem.1—When you are troubleshooting routing issues. Table 6-3 provides the common troubleshooting commands for RIP. IGRP. Expect some repetition in commands.qxd 7/28/06 8:58 AM Page 165 Day 6 ■ Make sure that authentication is set up correctly. and OSPF. ■ Create and implement an action plan. ■ If the plan does not work.

You can also pick out the troubleshooting command questions from pages 425–454 of the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study.30_1587131749_DAY06. Your Notes .qxd 166 7/28/06 8:58 AM Page 166 31 Days Before Your CCNA Exam Summary The absolute best way to learn these commands is to have someone else royally mess up your network routing configurations and put you to work finding the errors. Second Edition for a quick review. exam #640-801).

You can resume a session by using the resume command followed by the host or IP address or by using the Enter key. then x key combination. Module 4 4. The Cisco Networking Academy Program discusses IP addressing troubleshooting commands in Modules 4 and 9 of CCNA 2.6—A quick way to test all seven layers of the OSI model is with the telnet command. If Telnet does not function. and to disconnect a specific session. If you telnet to a router by hostname. The following command will initiate a Telnet session with another router: telnet {remote-router-ip-address | remote-router-hostname} Example 5-1 Initiate a Telnet Session Using an IP Address Router#telnet 192.2 Example 5-2 Initiate a Telnet Session Using a Hostname Router#telnet RouterB You can suspend a Telnet session with the Ctrl-Shift-6. To view all of your sessions. you can type disconnect followed by the host or IP address. you can test Layer 3 network connectivity using the following commands: ping traceroute show ip route . CCNA 2.0. you need to make sure that you have configured Domain Name System (DNS) or the ip host command on your router. You can specify up to five (0 through 4) vty sessions on a router to allow incoming Telnet connections to your router. All configurations and protocols have to function correctly to support a Telnet session.qxd 7/28/06 8:58 AM Page 167 Day 5 Troubleshoot IP Addressing and Host Configuration When you understand the design and configuration of a network. Telnet operates at the application layer of the OSI model and allows you to connect remotely to another router.2.168.1–4. simple commands such as ping and telnet provide great troubleshooting tools.31_1587131749_DAY05. you can type show sessions.2. The extended ping command on a router enables you to set very specific options when testing your IP configurations.

Timestamp.31_1587131749_DAY05. Module 9 9.2.5—To use the extended ping command. Strict. Record.0. You could also flip through pages 255–258 in the CCNA Flash Cards book. you type ping and press Enter and then specify the options shown in Example 5-3.qxd 168 7/28/06 8:58 AM Page 168 31 Days Before Your CCNA Exam CCNA 2. Example 5-3 The Extended ping Command Router#ping Protocol [ip]: Target IP address:192.2 Repeat count [5]: Datagram size [100]: Timeout in seconds [2]: Extended commands [n]:y Source address or interface:192.0. This short chapter just begs you to take a CCNA practice exam today.168. Second Edition. . Verbose[none]: Sweep range of sizes [n]: Summary Often a mistyped IP address or incorrectly configured subnet mask proves to be the problem in a network that will not return a successful ping. Schedule a Cisco Networking Academy practice CCNA exam with your instructor or use the exam on the CD-ROM that accompanies the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study.1 Type of service [0]: Set DF bit in IP header? [no]: Validate reply data? [no]: Data pattern [0xABCD]: Loose.168. exam #640-801).

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5.” and Day 6. Step 3 Document your work. If part of the command was understood.1. .2. Module 1 1. Module 4 4. CCNA 2. Module 2 2. “Troubleshoot IP Addressing and Host Configuration. CCNA 1.2. These troubleshooting topics originate from Module 1 from CCNA 1 and Modules 2.2. “Customize a Switch Configuration to Meet Specified Requirements and Manage System Image and Device Configuration Files (Two Objectives).” as a review of key show. Step 2 Cycle through each layer of the OSI model to fix the problem starting at Layer 1. CCNA 2.9—You can use the same basic steps to troubleshoot all network devices: Step 1 Collect information.10—As you troubleshoot a router.” and Day 7. 4. CCNA 2. “Perform LAN and VLAN Troubleshooting. Before restoring a captured configuration. be sure to delete unwanted text and add no shutdown to all configured interfaces. You can also use the show version command to determine the Cisco IOS software version running on the router and what commands are supported. Once you have verified Layer 3 connectivity.2. the ping and traceroute commands allow you to check Layer 3 connectivity on your network.2.4—As described on Day 12. debug. “Troubleshoot Routing Protocols. Module 5 5.” you can quickly fix a configuration issue with a router by restoring an earlier running-config capture with your terminal program. You can look for the carat symbol (^) to determine the portion of the command that the router did not understand. you can type that portion of the command followed by a question mark (?) to view the options for that command.32_1587131749_DAY04.qxd 7/28/06 8:58 AM Page 171 Day 4 Troubleshoot a Device as Part of a Working Network Today combines with Day 5. you can use Telnet to test all seven layers of the OSI model. some commands may not work. and connectivity-related commands.9 and 2. and 9 from CCNA 2.5 and 4.6—As mentioned on Day 5.

3. displays the type of cable that is connected and whether clocking is detected on the interfaces of the router. traceroute Identifies each hop on a path between two destinations. The debug all command displays all events and uses system resources to the point that it should not be implemented on a production router. Summary As mentioned yesterday. protocol events. including connected and known networks. The traceroute command allows you to isolate the interface that is dropping packets on a network. networks that are being advertised. including error messages. the source of routing updates. this command is useful. If you are remotely connected to a router and cannot physically inspect the cables. Debug can be processor intense and should be used only to troubleshoot. exam #640-801). show ip protocols Displays configured protocols. If show ip route provides no information other than connected routes. show controllers If a cable is connected. and which interfaces are sending updates. Pages 231–238 of the CCNA Flash Cards and Exam Practice Pack (CCNA SelfStudy. and interface events. The command undebug all or no debug all turns off all debugging. you need to spend time using these troubleshooting commands to identify and fix network issues. terminal monitor Redirects debug information to a remote terminal session.4–9.7—Table 4-1 provides a list of some common troubleshooting commands and tactics: Table 4-1 Troubleshooting Commands Command Definition show ip route Allows you to view all information provided to the router through configured routing protocols. . Lab time or practice with a simulator will strengthen your knowledge of these topics.32_1587131749_DAY04. Module 9 9. you can check configured routing protocols with the show ip protocols command.3. Second Edition also review these topics. debug Shows events on the router as they occur.qxd 172 7/28/06 8:58 AM Page 172 31 Days Before Your CCNA Exam CCNA 2.

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Pages 473–476 in the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study.4—Where you place an ACL on a router can affect how it filters packets. One way to remember this is to think that you always stand at your destination when you arrive.qxd 7/28/06 8:59 AM Page 175 Day 3 Troubleshoot an Access List The final installment in the review about access lists provides a list of show commands outlined in Module 11 from CCNA 2 that help you to see how the lists are configured. or retake. CCNA 2. Take. Table 3-1 Access List show Commands Command Function show ip interface Displays interface information. exam #640-801). Remember that you place standard access lists as close to the destination of the traffic you want to filter and place extended access lists as close to the source of the traffic you want to filter. a Cisco Academy online practice CCNA exam and then have somebody wreak havoc on an access list configuration for you to fix.2. including access list configurations 11. Summary Short day. Do not forget that all statements end with an implicit deny by default unless you specify otherwise.33_1587131749_DAY03. and you can verify access lists with the commands outlined in Table 3-1. . including whether an access list is assigned show access-lists Displays all access lists on a router show running-config Shows the entire running configuration. Keep in mind that troubleshooting also requires you to review your design and protocols to check access list functionality.1. ok…anyway. Second Edition can help you review today as well. Module 11 11. Stand…standard.5—You can test your access lists by creating sample traffic on your network.

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CCNA 4. As you recognize these commands. Table 2-1 displays all the options that you can use with the debug ppp command. Table 2-1 PPP Troubleshooting Command Definition debug ppp authentication Displays authentication messages between routers debug ppp packet Displays sent and received PPP packets debug ppp negotiation Displays PPP packets during PPP startup as negotiation occurs debug ppp error Displays PPP protocol errors and statistics debug ppp chap Displays Challenge Handshake Authentication Protocol (CHAP) packets CCNA 4.2.3.qxd 7/28/06 8:59 AM Page 177 Day 2 Perform Simple WAN Troubleshooting Cisco IOS software provides a number of show and debug commands to troubleshoot WAN connectivity. you can verify PPP encapsulation with the show interface command and use the debug ppp command. and 5 of CCNA 4 in the Cisco Networking Academy curriculum. 4. Module 3 3. . it is important to note the protocol and concept that you are troubleshooting.34_1587131749_DAY02. you can use the following two commands to view ISDN Layer 2 messages: debug isdn q921 debug isdn q931 You can also use the debug ppp commands previously discussed to identify and troubleshoot Layer 2 issues.5—To troubleshoot a serial connection. Module 4 4. These commands are outlined in Modules 3.4—You can verify ISDN with the following commands: show interface show isdn status If show isdn status does not show Layer 1 as ACTIVE and Layer 2 as MULTIPLE_FRAME_ESTABLISHED.

7—The command debug frame-relay lmi allows you to view sent and received Local Management Interface (LMI) packets. The more you see the output and recognize key variables.2. Module 5 5. Table 2-2 DDR Troubleshooting Command Definition Debug isdn q921 Used to observe signaling events between the router and the ISDN switch. A type 0 full LMI status message can provide further information with the following hex values: ■ The value 0x0 indicates added/inactive or that the data-link connection identifier (DLCI) is programmed but not usable. ■ The value 0x2 indicates added/active or that the DLCI is usable and functioning properly.3. but is no longer programmed. Second Edition also review WAN troubleshooting and verification. Summary Test the commands described today on a router if you have time. exam #640-801).qxd 178 7/28/06 8:59 AM Page 178 31 Days Before Your CCNA Exam 4.9—The commands in Table 2-2 provide troubleshooting information for dial-on-demand routing (DDR). the quicker you will be able to answer related questions in the CCNA exam.2. . Pages 541–546 and 571–574 in the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study.6—The following commands can be used to verify Frame Relay: show interfaces show frame-relay lmi show frame-relay pvc show frame-relay map 5. such as obtaining a terminal endpoint identifier (TEI) dynamically Debug isdn q931 Displays call setup information for outgoing and incoming calls Debug dialer packets Displays DDR link connections and interesting traffic that caused the connection Debug dialer events Displays packets sent to the DDR interface isdn call interface interface Forces the local router to dial the remote router Clear isdn bri Clears established connections and resets the interface CCNA 4. ■ The value 0x4 indicates deleted or that the DLCI was programmed at one point.34_1587131749_DAY02.

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qxd 7/28/06 8:59 AM Page 181 Day 1 Key Points from Each Day for Relaxed Skimming Today you should try to take a timed practice test using either the Cisco Academy practice CCNA or the exam simulation that accompanies the CCNA Flash Cards and Exam Practice Pack (CCNA Self-Study. SQL Data 3 Transport 4 Transport End-to-end communications. Today you also focus on the common CCNA details that may show up on the exam. Table 1-1 The TCP/IP Model Versus the OSI Model TCP/IP Model OSI Model Key Points PDU 4 Application 7 Application User interaction Data 6 Presentation Encryption and compression Data 5 Session Session control. The following sections outline the details from each day that you should feel comfortable with. Treat today as if you were skimming through a configuration file to find the key details of a router configuration. Second Edition. exam #640-801). Day 31 The benefits of using a layered model are as follows: ■ Reduces complexity ■ Standardizes interfaces ■ Facilitates modular engineering ■ Ensures interoperable technology ■ Accelerates evolution ■ Simplifies teaching and learning Table 1-1 provides an overview of both the TCP/IP model and the OSI model. switch Frames 1 Physical Media and signals. Something as simple as a default TCP port number or a default administrative distance can quickly highlight the correct answer in the CCNA exam. routers Packets 1 Network Access 2 Data link LLC and MAC.35_1587131749_DAY01. including a short description and the protocol data unit (PDU) for each layer. hub Bits . TCP and UDP Segments 2 Internet 3 Network Path determination. or at least be able to recognize as part of a larger concept.

■ Elect a root bridge—The switch with the lowest bridge priority becomes the root bridge. all ports are in the blocking or forwarding state until there is a topology change. ■ Cycle ports through the STP states—After the network has converged. Table 1-3 Spanning-Tree Port States Port State Description Blocking The port looks only at BPDUs. Table 1-3 describes the port states. Listening The port checks for multiple paths to the root bridge and blocks all ports except the port with the lowest cost path to the root bridge.qxd 182 7/28/06 8:59 AM Page 182 31 Days Before Your CCNA Exam Table 1-2 Application Layer Protocols and Transport Layer Ports Application Layer Protocol Transport Layer Port/Protocol http Port 80 TCP Connection-Oriented FTP Port 21 TCP Connection-Oriented FTP-Data Port 20 TCP Connection-Oriented Telnet Port 23 TCP Connection-Oriented SMTP Port 25 TCP Connection-Oriented DNS Port 53 UDP and TCP TFTP Port 69 UDP Connectionless SNMP Port 161 UDP Connectionless Day 30 Switches perform the following Spanning Tree Protocol (STP) actions to prevent loops in a redundant switched network: ■ Send out bridge protocol data units (BPDUs)—Each switch sends BPDUs that include the bridge ID (BID) containing the bridge priority and MAC address. Forwarding The port learns MAC addresses. Learning The port learns MAC addresses but does not forward data. .35_1587131749_DAY01. ■ Specify a root port—The port with the best bandwidth connection (lowest cost path) becomes the root or designated port. forwards data. and processes BPDUs.

Mesh All devices connected to all other devices. Uses CSMA/CD. FDDI is a logical ring topology. Routers use the LSAs to build a full topology of the network. . Routers use the Shortest Path First (SPF) algorithm and LSAs to build a shortest path tree as well as a routing table. Routers send link-state advertisements (LSAs) to update other routers. Star All devices connected to a hub or switch. Table 1-4 LAN Topologies Topology Description Bus All devices are connected.35_1587131749_DAY01. Ethernet is a logical bus topology. Routers flood LSAs only when there is a topology change. ■ Cut-through—In cut-through mode. Switches can operate in cut-through or store-and-forward modes: ■ Store-and-forward—Store-and-forward mode results in the switch receiving the entire frame before forwarding the information. a switch either sends the frame as soon as it knows the destination MAC address (fast-forward) or the switch reads the first 64 bytes and then sends the frame (fragment-free). Routers use a metric to determine the cost path for a route and build a routing table. Routers see only neighboring routers.qxd 7/28/06 8:59 AM Page 183 Day 1 183 Day 29 Table 1-4 describes the different LAN topologies. Hierarchal A pyramid of physical star networks connected to a main proxy. These topologies can describe logical or physical characteristics of a LAN. Ethernet is an example of a nondeterministic physical star topology. To develop a full loop-free topological database requires more memory in a router. Day 28 Table 1-5 compares the features of distance vector and link-state protocols. Table 1-5 Distance Vector and Link-State Protocols Distance Vector Link-State Routers send periodic updates of the entire routing table to neighbors. This topology is deterministic. Ring Hosts connected to other hosts.

To avoid a single point of failure. they also elect a backup designated router (BDR). Backup routes.0. and E IP Addresses Class Binary Start 1st Octet Range Network (N) and host (H) Octets Number of Hosts Bits in Network Address Class A 0 1–126* N.H. If the connection is point-to-point. ■ The neighboring and topology table allow EIGRP to use DUAL to identify the best route. D.H. ■ Enhanced Interior Gateway Routing Protocol (EIGRP) uses a neighboring table in the same way that OSPF uses an adjacency database to maintain information on adjacent routers. triggered updates. C.0.10 to communicate with neighbors. and E IP addresses. however. D. ■ Split horizon does not allow a router to send an update for a route to the router that originally advertised the route. If the connection is multiaccess.0 is reserved for the loopback.N. B.0. are kept only in the topology table.0.5.N.H Multicast 28 Class E 1111 240–255 RESEARCH RESEARCH RESEARCH * The Class A address 127. Routers that are connected on broadcast multiaccess networks such as fiber or Ethernet or nonbroadcast multiaccess networks such as Frame Relay elect a single router called the designated router (DR) to handle updates. B. and enter it into the routing table. ■ If you were to run Open Shortest Path First (OSPF) on a fiber network. EIGRP.H.H About 16 million 8 Class B 10 128–191 N.H 65.qxd 184 7/28/06 8:59 AM Page 184 31 Days Before Your CCNA Exam Routers can avoid loops with the following tactics: ■ You can combine route poisoning with the maximum hop count.0.H. . ■ EIGRP sends hello packets on 224. ■ OSPF hello packets typical to link-state protocols go out over the multicast address 224.35_1587131749_DAY01.H 254 24 Class D 1110 224–239 H. or feasible successor routes. OSPF avoids a network of never-ending neighbors with an election. Day 27 Table 1-6 explains Class A. C.0.N. Table 1-6 Class A. the packets go out every 30 seconds. and a holddown timer to prevent routing loops. uses a distance-vector diffusing update algorithm (DUAL) to recalculate a topology.H. all routers would technically be connected on the fiber ring to each other. the hellos go out every ten seconds. or the successor route.535 16 Class C 110 192–223 N. This means that each router would be a neighbor to every other router.

IP address assignment occurs at Layer 3. it loads the configuration file from NVRAM. and initializes the IOS from flash. ■ TCP uses positive acknowledgment. and TCP functions: ■ Address Resolution Protocol (ARP) finds a MAC address using the IP address.qxd 7/28/06 8:59 AM Page 185 Day 1 185 The following points discuss ARP. or ROM. registered ports (1024 to 49151). Once the IOS is loaded. loads a bootstrap. ■ The process in sliding windows where TCP requests that a host resend information is called positive acknowledgement and retransmission (PAR). and a three-way handshake and is the Layer 4 connection-oriented protocol. ■ User Datagram Protocol (UDP) is the Layer 4 connectionless protocol and relies on upper layers for error correction. it first performs a power-on self test (POST). An example could be a web server that provides HTTP access on port 80 at the same time as Telnet access on port 23. ARP occurs when a host has a destination IP address for a packet but needs to determine the MAC address to send the packet over the LAN. The repeater would only regenerate the bad frame and not the simultaneous TX and RX.35_1587131749_DAY01. IP. The location of the IOS can be specified in the configuration register. Day 25 A local collision occurs when a network card notices that the receive (RX) wires and the send (TX) wires are active at the same time. the Cisco IOS software searches for a TFTP server to load the configuration file. and MAC address assignment occurs at Layer 2. sliding windows. ■ A more concise definition of port number ranges includes well-known ports (0 to 1023). If there is no TFTP server. A remote collision occurs when a frame is too small but does show the same symptoms as a local collision. the IOS starts the setup dialog. and dynamic ports (49152 to 65535). Day 26 Consider the following full image name: C2600-is-mz The following defines the image name sections: ■ C2600 = platform = Cisco 2600 series ■ is = feature set = IP Plus ■ mz = image location/compression = RAM/zipped When a Cisco router powers up. ■ Port number assignment occurs at Layer 4 of the OSI model. . A remote collision is likely the result of a local collision on the other side of a hub or repeater. ■ A host can provide services simultaneously on two different ports. If there is no configuration file in NVRAM. a TFTP server.

Frame Relay switches create a virtual circuit (VC) between communicating hosts that exists only when the frame is being transferred.255 ■ Class B 172. wildcard masks serve an entirely different function from subnet masks.0.255 . and C address ranges for private LANs.255.0 to 192.31.168. The wildcard mask 0. Runts are usually made up of collision fragments. A runt is a frame that is below the minimum size of 64 octets.255.35_1587131749_DAY01. You can define a dialer-list on a Cisco router that tells the router what traffic should cause it to bring up a DDR link.0. 0. it is considered a cyclic redundancy check (CRC) error.0 can also be represented by the term any or host in an ACL.168. A frame that exceeds the maximum legal frame size will cause a network diagnostic tool to report jabber on the connection.0. Day 23 RFC 1918 states that there are reserved Class A.0.255.0. Day 24 A WAN connection uses a Layer 2 frame to encapsulate data. Some common data link layer WAN encapsulation types include the following: ■ Cisco proprietary HDLC ■ PPP ■ LAPB Frame Relay is an example of a Layer 2 WAN connection-oriented packet-switching system where the route is determined by switches and each frame carries an identifier called a data-link connection identifier (DLCI).0. Dial-on-demand routing (DDR) interesting traffic is network activity that causes a router to connect to a network. The Layer 2 network card cannot recognize this type of collision and must rely on the upper layers to request retransmission.qxd 186 7/28/06 8:59 AM Page 186 31 Days Before Your CCNA Exam A late collision occurs after the first 64 bits of data have been transmitted for a frame.0. and the ISDN connection allows for a PPP-encapsulated link. A binary 1 means ignore and a binary 0 means match in a wildcard mask.255. The ISDN delta (D) channel is used to set up the call and for signaling.255 ■ Class C 192.0.0 to 172.0 states that the access control list (ACL) should match the entire host. Do not look for a relationship between wildcard masks and subnet masks. ISDN bearer (B) channels carry data at 64 kbps for each channel.0 to 10. The VC is identified by the DLCI. The private ranges are as follows: ■ Class A 10.16. The call with Integrated Services Digital Network (ISDN) is faster than a modem. If a frame does not match its own frame check sequence (FCS). B.

Routers can also act as firewalls and provide a WAN connection. which connect through horizontal cross-connects (HCCs) to hosts. Data link (2) To microsegment collision domains you should use switches.35_1587131749_DAY01. Switch ports have only two hosts per collision domain with a source and destination host. Table 1-8 Class C Subnet Chart Bits Borrowed 1 2 3 4 5 6 7 8 Slash format /25 /26 /27 /28 /29 /30 /31 /32 Mask 128 192 224 240 248 252 254 255 Bits borrowed 1 2 3 4 5 6 7 8 Total subnets 2* 4 8 16 32 64 N/A N/A Usable subnets* 0* 2* 6* 14* 30* 62* N/A N/A Total hosts 128* 64 32 16 8 4 N/A N/A Usable hosts 126* 62 30 14 6 2 N/A N/A *Stars refer to CCNA 3. Table 1-7 LAN Design by OSI Layer OSI Layer Design Considerations Network (3) Routers commonly forward data based on IP addressing and connect LANs and divide broadcast domains between LANs. but you need a router to communicate between VLANs. Physical (1) Fiber optic for distances over 100 meters and unshielded twisted pair (UTP) for 100 meters or less. The use of hubs instead of switches increases the size of collision domains to all hosts connected and affects bandwidth. The /25 subnet is sometimes usable as well as total subnets (all 0s and all 1s) in later versions of the IOS and if you enter the ip subnet zero command. You can divide Layer 2 switches into VLANs to separate networks at Layer 3. Day 22 You can use Table 1-8 to quickly determine the details necessary to subnet a Class C network. Module 1.qxd 7/28/06 8:59 AM Page 187 Day 1 187 Table 1-7 outlines LAN design considerations divided by OSI layer. . The main distribution facility (MDF) connects through the vertical cross-connects (VCCs) to the intermediate distribution facilities (IDFs).

Metropolitan-area network (MAN) Connect LANs in a metropolitan area using private lines. Table 1-10 Network Types Network Type Designed To: Wide-area network (WAN) Connect LANs using serial interfaces over a large geographic area to provide remote resources.0. Supports variable-length subnet mask (VLSM). updates only when there is a change in topology. hybrid Uses both link-state and distance vector features and multicasts updates on 224. fault-tolerant. Routing Information Protocol Version 2 (RIPv2) 120 Interior. Storage-area network (SAN) Provide high-performance. Supports VLSM. Virtual private network (VPN) Provide a private network that exists inside of a public network. or optical services.35_1587131749_DAY01.0. Table 1-9 Routing Protocols Protocol Name AD Type Description Routing Information Protocol (RIP) 120 Interior.qxd 188 7/28/06 8:59 AM Page 188 31 Days Before Your CCNA Exam Day 21 Table 1-9 charts the routing protocols discussed in the Cisco Networking Academy curriculum. Border Gateway Protocol (BGP) 20 Exterior. a wireless bridge. and Internet access. Interior Gateway Routing Protocol (IGRP) 100 Interior. Day 20 Table 1-10 defines four types of internetworks. Clients connect through a secure tunnel to the VPN router at the destination. scalable storage for servers over a separate network from the client/server network. distance vector Broadcasts updates every 90 seconds and uses bandwidth. . OSPF 110 Interior. distance vector Used to route between autonomous systems. distance vector Multicasts updates every 30 seconds using the address 224. link-state Nonproprietary protocol.9 and includes subnet mask in updates. load.10. distance vector Broadcasts updates every 30 seconds and uses hop count as the metric with a maximum of 16. e-mail. EIGRP 90 Interior.0.0. and delay as a metric.

■ At the end of every ACL. ■ Place standard ACLs closest to the destination. ■ Place extended ACLs closest to the source.35_1587131749_DAY01. Frame Relay Packet-switched Uses DLCIs to identify circuits and LMI messages to learn about the network. PRI has 1 signaling channel and 23 data channels. Table 1-11 highlights key points about ISDN. Frame Relay.qxd 7/28/06 8:59 AM Page 189 Day 1 189 Day 19 Remember the following points about ACLs: ■ The way to revise an ACL is to delete and recreate it unless you are using a named ACL and can add statements to the end. ■ Do not work with an access list that is applied and active. it sends an ICMP implicit deny. ATM Cell-switched High-bandwidth WAN protocol that uses a 53-byte cell. ■ Outbound ACLs do not affect traffic originating from the router. ■ When an IP ACL rejects a packet. there is an implicit deny. then LCP opens the connection with a configuration acknowledgment frame. Table 1-12 PPP Session Establishment Phase Description Link-establishment phase Each device sends Link Control Protocol (LCP) frames and negotiates LCP options. ■ A router stops checking ACL statements after the first match. continues . Day 18 WAN protocols operate at the physical and data link layers of the OSI seven-layer reference model. ■ An ACL should filter specific addresses first and then groups of addresses. and ATM. ■ A router checks ACL statements in the order in which you create them. Table 1-11 WAN Connection and Protocol Examples WAN Protocol Network Type Key Points ISDN Circuit-switched BRI has 1 channel for signaling and 2 channels for data. and Table 1-12 describes PPP session establishment. Good for video and streaming applications. ■ You can apply to each interface one ACL per protocol per direction.

0.qxd 190 7/28/06 8:59 AM Page 190 31 Days Before Your CCNA Exam Table 1-12 PPP Session Establishment continued Phase Description Authentication phase (optional) The established link can authenticate using Password Authentication Protocol (PAP) or Challenge Handshake Authentication Protocol (CHAP) and also check link quality.0.921 link access procedure on the D channel (LAPD) and the Q. Day 17 Table 1-13 lists the syntax for different types of routing protocols. including Q. The NT2 connects at the T reference to the NT1. and the NT1 connects at the U reference to the local loop. Network layer protocol phase PPP devices send Network Control Protocol (NCP) packets to configure network layer protocols and allow Layer 3 transmission.35_1587131749_DAY01. Table 1-13 Routing Protocol Command Syntax Protocol Commands Static ip route destination-network subnet-mask {outgoing-interface | nexthop-address} Default ip route 0.0 0. so you first connect at the R reference to the terminal adapter (TA) and then to the NT2. The NT2 connects at the T reference to the network termination type 1 (NT1). and the NT1 connects at the U reference to the local loop. ■ You have a TE2 that is not native ISDN. so you may sometimes see an S/T interface.0 {outgoing-interface | next-hop-address} RIP router rip network directly-connected-network IGRP router igrp autonomous-system-number network directly-connected-network OSPF router ospf process-id network network-address wildcard-mask area area-id exit . The three categories of ISDN protocols are as follows: ■ E series—Telephone network standards ■ I series—ISDN concepts and terminology ■ Q series—How switching and call setup (signaling) function.0. S and T references can be similar.931 ISDN network layer The following two examples describe ISDN reference points: ■ You have a TE1 that is a native ISDN interface that connects at the S reference to the customer switching network termination type 2 (NT2).0.

qxd 7/28/06 8:59 AM Page 191 Day 1 Protocol 191 Commands interface loopback 0 ip address ip-address subnet-mask OSPF simple authentication interface interface ip ospf authentication-key password exit area area-number authentication OSPF authentication with MD5 interface interface ip ospf message-digest-key key-id md5 key area area-number authentication message-digest exit router ospf process id area area-id authentication message-digest EIGRP router eigrp autonomous-system-number network network-number eigrp log-neighbor-changes bandwidth bandwidth no auto-summary Day 16 You use the following command syntax to configure a serial interface. interface type slot/port ip address ip-address netmask clock rate clock-rate no shutdown Example 1-1 Configuring a Serial Interface Router>enable Router#configure terminal Router(config)#interface serial 0/0 Router(config-if)#ip address 172.255.16.255. You will only use the clock rate command if the interface is data communications equipment (DCE).0 Router(config-if)#clock rate 56000 Router(config-if)#no shutdown .35_1587131749_DAY01.1 255.1.

0.1.200. and DHCP. Table 1-14 Set the Console and vty Passwords Console Password Configuration VTY Password Configuration line console 0 line vty 0 4 password cisco password cisco login login Table 1-15 NAT and DHCP Configuration Commands Static NAT Configuration DHCP Configuration ip nat inside source static local-IP global-IP ip dhcp pool pool-name interface interface network network-address subnet-mask ip nat outside default-router default-router-address interface interface dns-server dns-server-address ip nat inside domain-name domain-name Example 1-2 NAT Configuration with Overload for One Outside IP Address Router(config)#access-list 1 permit 192.255 Router(config)#ip nat pool isp-pool 209.0 0.224 Router(config)#ip nat inside source list 1 pool isp-pool overload Router(config)#interface serial 0 Router(config-if)#ip nat outside Router(config-if)#interface fa 0/0 Router(config-if)#ip nat inside .225 209.255.255 Router(config)#ip nat inside source list 1 interface serial 0 overload Router(config)#interface serial 0 Router(config-if)#ip nat outside Router(config-if)#interface fa 0/0 Router(config-if)#ip nat inside Example 1-3 NAT Configuration with Overload for a Pool of Outside IP Addresses Router(config)#access-list 1 permit 192.0 0.35_1587131749_DAY01.0.168.165.0.200.168.0.1. vty.165.qxd 192 7/28/06 8:59 AM Page 192 31 Days Before Your CCNA Exam Day 15 Table 1-14 and Table 1-15 recount additional router configurations such as console. NAT.235 netmask 255.255.

However. Table 1-16 and Table 1-17 define Virtual Terminal Protocol (VTP) modes and provide static VLAN. You would use 802. Trunk.1q to connect a Cisco switch to a non-Cisco device. Transparent Only forward advertisements Does not modify its VLAN database. ■ VLAN membership provides security settings assigned for each logical group. geographic VLANs have become more common than end-to-end VLANs. but as previously stated geographic VLANs are more common. and VTP configuration commands. ■ VLAN membership can be configured to follow the users when they change location on the network in an end-to-end network. modify. and delete VLANs Sends VTP messages out all trunk ports and saves VLAN configuration in the NVRAM. Table 1-17 Switch Static VLAN. Table 1-16 VTP Switch Modes VTP Mode Capabilities Definition Server Can create. but forwards received VTP messages.1Q. trunk.qxd 7/28/06 8:59 AM Page 193 Day 1 193 Day 14 Remember the following points about VLANs: ■ VLAN membership is based on job assignment regardless of location (referred to as end-toend).35_1587131749_DAY01. ■ The two types of frame tagging are Cisco proprietary Inter-Switch Link (ISL) and IEEE 802. VTP clients process changes and forward messages. and delete VLANs Better for switches that do not have enough memory for large configurations. and VTP Configuration Commands Configuration Type Commands Static VLAN vlan database vlan vlan-number interface interface switchport access vlan vlan-number Trunk switchport trunk encapsulation {isl | dot1q} VTP vlan database vtp v2-mode vtp domain domain vtp {client | server | transparent} vtp password password . due to the wide use of Internet access. modify. Client Cannot create.

typically a serial port on a host to a console port on a router or switch Day 12 Bridges and switches divide collision domains and filter at Layer 2.qxd 194 7/28/06 8:59 AM Page 194 31 Days Before Your CCNA Exam Day 13 Table 1-18 provides a description for different types of UTP networking cable. Table 1-18 UTP Cabling for Network Devices Cable Used to Connect Description Crossover cable Switch to switch TIA/EIA-568-A on one end and TIA/EIA-568-B on the other end. Router to hub Host/server to switch Host/server to hub Rollover cable Terminal to console Pins 1–8 reversed on either end. if there is no other option. 2. and lastly. configuration. then looks for a TFTP server that could have the IOS. the router first looks for a configuration file in the NVRAM. Once the Cisco IOS software is loaded. then looks for a TFTP server that might have the configuration. Each port on a bridge or switch is microsegmented into its own collision domain. 3. The router first looks for the Cisco IOS software in the flash memory. Often converted to 9-pin port on a device for serial on one end. The router checks the hardware (POST) and loads the bootstrap code from the read-only memory (ROM). loads a stripped version of the IOS from ROM. Layer 2 switches can also divide broadcast domains with VLANs. but you need a router to communicate between VLANs. Layer 3 switches and routers filter at Layer 3 of the OSI model and divide broadcast domains. and lastly. A router starts using the following sequence: 1. Switch to hub Hub to hub Router to router Host/server to host Router to host Straight-through cable Router to switch TIA/EIA-568-A on both ends or TIA/EIA-568-B on both ends.35_1587131749_DAY01. if there .

Use b to boot the system. Table 1-19 Router Configuration and Image Backup Commands Configuration Backup Image Backup copy running-config tftp copy flash tftp copy tftp running-config copy tftp flash xmodem -c image-file-name set tftpdnld Cisco IOS release 12. use the show version command to see if the configuration register value is 0x2142. the system boots the first image in flash. Table 1-19 lists router configuration and backup commands. Table 1-20 Configuration Register Values Register Value Example Description 0x___0 0x2100 System enters ROM monitor mode.qxd 7/28/06 8:59 AM Page 195 Day 1 195 is no configuration. 0x___1 0x2101 Boots the first image in flash. If there are no commands.0 and later: copy location:URL location:URL The following commands allow you to define how a router will boot: boot system flash IOS-filename boot system tftp IOS-filename tftp-address boot system rom config-register configuration-register-value Table 1-20 deciphers the values in the configuration register. This setting will boot the limited ROM version on older platforms.35_1587131749_DAY01. 0x2102 Looks in the NVRAM for boot system commands. The specific example 0x2142 ignores any configuration in the NVRAM. 0x2102 would apply the configuration in the NVRAM. outputs a set of questions to the console to ask the user for configuration parameters. If your router boots to a nonconfigured router (and you saved to startup-config). 0x___2 to 0x___F 0x2142. .

35_1587131749_DAY01. Table 1-21 Cisco IOS Editing Keys and Commands Command/Keystroke Definition Tab Automatically complete a command Ctrl-P or Up Arrow Repeat previously typed commands Ctrl-A Move to the beginning of a command line Esc-B Move back one word Ctrl-B or Left Arrow Move back one character Ctrl-E Move to the end of the command line Ctrl-F or Right Arrow Move forward one character Esc-F Move forward one word Ctrl-Z Exit configuration mode show history Display the command buffer terminal history size number Set the history buffer size terminal no editing Turn off advanced editing terminal editing Enable advanced editing Table 1-22 Common Initial Router Commands and Switch Commands Router Commands Switch Commands enable enable configure terminal configure terminal hostname hostname hostname hostname banner motd copy running-config startup-config enable secret password copy running-config startup-config .qxd 196 7/28/06 8:59 AM Page 196 31 Days Before Your CCNA Exam Day 11 Table 1-21 and Table 1-22 cover the keystrokes used in the Cisco IOS software as well as editing commands and initial router commands.

ISDN. Table 1-24 WAN Configuration Commands Protocol Basic Commands PPP encapsulation ppp compress {predictor | stac} ppp quality {1 to 100 as a percentage} ppp multilink username name password secret-password encapsulation ppp ppp authentication {chap | chap pap | pap chap | pap} ppp pap sent-username username password password continues .qxd 7/28/06 8:59 AM Page 197 Day 1 197 Day 10 Table 1-23 provides the commands needed to configure different ACLs. DDR.35_1587131749_DAY01. Table 1-23 Access List Commands ACL Type ACL Commands Standard access-list ACL-number {deny | permit} source-address wildcard ip access-group ACL-number {in | out} Extended access-list ACL-number {deny | permit} protocol source wildcard-mask destination wildcard-mask operator port ip access-group ACL-number {in | out} Restrict VTY access-list ACL-number {deny | permit} source-address wildcard-mask ip access-class ACL-number {in | out} Named ACL access-list {extended | standard} name {deny | permit} protocol source wildcard destination wildcard-mask operator port ip access-group ACL-number {in | out} You can use numbers from the following ranges to identify a numbered access list: ■ Standard IP ACL—Numbers 1–99 or 1300–1999 ■ Extended IP—Numbers 100–199 or 2000–2699 ■ AppleTalk—Numbers 600–699 Day 9 Table 1-24 lists the commands that you would use for PPP. and Frame Relay.

legacy dialer-list number protocol protocol {permit | deny | list [access-list-number]} interface interface dialer-group number dialer idle-timeout seconds-after-last-traffic dialer map ip next-hop name next-hop-hostname dial-number DDR.35_1587131749_DAY01. dialer profiles dialer-list number protocol protocol {permit | deny | list [access-list-number]} interface dialer virtual-interface-number dialer-group number dialer remote name next-hop-hostname dialer string dial-number dialer-pool number dialer idle-timeout seconds-after-last-traffic dialer pool-member number priority priority Frame Relay (no LMI) encapsulation frame-relay {cisco | ietf} frame-relay map protocol protocol-address dlci broadcast Frame Relay encapsulation frame-relay {cisco | ietf} frame-relay lmi-type {ansi | cisco | q933a} interface serial subinterface-number {point-to-point | multipoint} frame-relay interface-dlci DLCI-number .qxd 198 7/28/06 8:59 AM Page 198 31 Days Before Your CCNA Exam Table 1-24 WAN Configuration Commands Protocol Basic Commands ISDN BRI isdn switch-type switch-type continued isdn spid{number} spid-number local-dial-number encapsulation ppp ISDN PRI controller t1 framing {sf | esf} linecode {ami | b8zs | hdb3} pri-group timeslots range interface serial {slot/port: | unit:} {23 | 15} isdn switch-type switch-type controller e1 framing {crc4 | no-crc4} linecode {ami | b8zs | hdb3} pri-group timeslots range interface serial {slot/port: | unit:} {23 | 15} isdn switch-type switch-type DDR.

DTE and DCE cable problems or transceiver issues. Table 1-25 OSI Model Troubleshooting Layer Common Issues Layers 7–4 Ping works. but Telnet does not work. Layer 2 Improper or missing configurations for clock rate and encapsulation. LED indicators and power LED–related issues. use the command show cdp neighbors. Day 7 Make sure that you are familiar with the following commands for LAN and VLAN troubleshooting: cdp run show debugging no cdp run debug cdp adjacency no cdp enable debug cdp events clear cdp counters debug cdp ip cdp enable debug cdp packets show cdp traffic cdp timer show cdp cdp holdtime show cdp neighbors show debug show cdp neighbors detail show vlan clear cdp table The command show cdp does not show information about neighboring devices.qxd 7/28/06 8:59 AM Page 199 Day 1 199 Day 8 Table 1-25 pinpoints the common issues you encounter on a network in relation to the OSI sevenlayer model. Telnet tests all seven layers of the OSI model. Layer 3 IP addressing and routing protocol configuration issues. . Layer 1 Incorrect cables.35_1587131749_DAY01. Ping tests Layer 3. To see information about neighboring devices. It tells you about the configuration of CDP on the device you are using.

170 show ip ospf neighbor iBGP.0/0 eBGP. you can type that portion of the command followed by a question mark (?) to view the options for that command. 115 no debug all RIP. 200 debug ip ospf events debug ip ospf packet Days 5 and 4 Be sure to remember the commands. and key combinations that you can use with the Cisco IOS software while troubleshooting a network.0. 120 show ip eigrp neighbors EIGRP (external).35_1587131749_DAY01. 5 ip route 0. Table 1-26 Routing Protocol Troubleshooting Commands Default Administrative Distances debug ip igrp events Directly connected. 0 debug ip igrp transactions Static. show ip route show ip protocols show controllers debug all terminal monitor traceroute ping You can look for the carat symbol (^) to determine the portion of the command that the router did not understand. 100 show running-config OSPF.qxd 200 7/28/06 8:59 AM Page 200 31 Days Before Your CCNA Exam Day 6 Table 1-26 specifies the commands that can aid you while troubleshooting a routing protocol. The telnet command can . If part of the command was understood. 1 ip default-network EIGRP summary route. concepts.0. 110 undebug all IS-IS. 20 show ip rip database EIGRP (internal). 90 show ip interface brief IGRP.

Day 3 Tahe following show commands can help you troubleshoot an access list: show access-lists show ip interface show running-config Standard access lists should be placed as close to the destination of the traffic you want to filter. the Cisco IOS software. All of the information in this book. What is possibly the most important factor for success on the exam is your attitude. Read with a smile. Good luck on the test. Treat each detail like a familiar old friend and not a hard. Use debug commands only when you are troubleshooting. I do realize that this last day is an abbreviation of my abbreviation of the Academy curriculum. while show commands provide a specific snapshot for a point in time on a network.qxd 7/28/06 8:59 AM Page 201 Day 1 201 be suspended with the keystroke Ctrl-Shift-6. and extended access lists should be placed as close to the source of the traffic you want to filter. Summary All the topics discussed today should be floating around in your head within reach for test day. . Your passion for this subject will come through on test day just as clearly as it will come through in a job interview or planning meeting. and the Academy Curriculum can be whittled down to just one four-letter word on your resume: CCNA.35_1587131749_DAY01. Day 2 The following commands allow you to troubleshoot WAN protocols such as PPP. You can look at all sessions with the command show sessions and use disconnect to disconnect a session and resume to resume a session. then x. and Frame Relay: debug ppp authentication debug isdn q931 debug ppp packet debug dialer packets debug ppp negotiation debug dialer events debug ppp error isdn call interface interface debug ppp chap clear isdn bri show isdn status debug frame-relay lmi debug isdn q921 Remember that debug commands are an ongoing presentation of changes on a network. cold obstacle. ISDN.

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36_1587131749_Pt5.qxd 7/28/06 8:59 AM Page 203 Part V Exam Day and Post-Exam Information Exam Day: Becoming a CCNA Post-Exam: After the CCNA Exam .

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Ninety minutes and 65 questions stand between you and your CCNA certification. What You Need for the Exam Write the exam location. and technology sections of the exam.com explains that the scoring scale . Use the following information to focus on the details specific to the day of your CCNA exam. and troubleshoot a network. or military identification. ■ The testing center will store any personal items while you take the exam. It is best to bring only what you will need. The report will also include your percentage in the planning and design. What You Should Receive After Completion When you complete the exam. date.qxd 7/28/06 8:59 AM Page 205 Exam Day Becoming a CCNA Today is your opportunity to prove that you know how to describe. The minimum score required to pass is around 800 (the minimum score listed on my last exam report was 849). you will see an immediate electronic response as to whether you passed or failed. ■ The test proctor will take you through the agreement and set up your testing station after you have signed the agreement. ■ The test proctor will give you a sheet for scratch paper or a dry erase pad. exam center phone number.37_1587131749_ExamDay. implementation and operation. plan. troubleshooting. Cisco. exam time. The proctor will give you a certified score report with the following important information: ■ Your score based on a scale of 300 to 1000 points. ■ You will be monitored during the entire exam. Do not take these out of the room. implement. passport. and the proctor’s name in the lines that follow: Location: Date: Exam Time (arrive early): Exam Center Phone Number: Proctor’s Name: Remember the following items on Exam Day: ■ You must have two forms of ID that include a photo and signature such as a driver’s license.

Summary Your state of mind is a key factor in your success on the CCNA exam. Bring earplugs in the off chance that your testing neighbor has a bad cough or any loud nervous habits. Arrive early to the exam. ■ Identification information that you will need to track your certification.qxd 206 7/28/06 8:59 AM Page 206 31 Days Before Your CCNA Exam could change without notice. Do not let an extremely difficult or specific question impede your progress. you can begin the exam with confidence and focus. . Do not lose your certified examination score report. so answer each question confidently and keep an eye on the timer.37_1587131749_ExamDay. If you know the details of the curriculum and the details of the exam process. You cannot return to questions on the exam that you have already answered. but the scoring has remained the same for the last three versions of the CCNA.

You will need your examination score report to log in to the certification tracking system and set up a login to check your certification status. be sure to add your CCNA certification to your resume. A master’s degree might be the exception to this rule. place your certifications or degrees in a section titled Education and Certifications.D. It is presumptuous to pretend that your latest certification is the equivalent to someone who has spent 4–7 years pursuing a Ph. 2005.38_1587131749_PostExam. Your certificate will be mailed to the address you provided when you registered for the exam. A certificate hanging on a wall is much harder to lose than a certificate in a filing cabinet or random folder.custhelp.com/ When you receive your certificate. Many network engineers have avoided the CCNA exam for years. you will receive your official CCNA certificate and wallet card about six weeks (eight weeks internationally) after exam day. . while simultaneously building your network of contacts that lead to your dream position. or some other advanced degree. Moran also discusses good strategies for breaking into the IT industry once you have earned your CCNA: The most important factor is that you are moving toward a career goal. ISBN: 1587131560): I don’t believe you should place your certifications after your name. You might not get the title or job you want right out of school. Receiving Your Certificate If you passed the exam. you must pass the CCNA again or pass another Cisco exam in a path to a professional level certification before the end of the three year period. you should be satisfied. Matthew Moran provides the following advice for adding certifications to a resume in his book. you may want to frame it and put it on a wall.qxd 7/28/06 9:00 AM Page 207 Post-Exam Information After the CCNA The accomplishment of signing up for and actually taking the CCNA exam is no small feat. You never know when an employer or academic institution could request a copy. The IT Career Builder’s Toolkit (Cisco Press. You must build your career piece by piece. If you do not receive your certificate. Instead. The following sections discuss your options after test day. you have to open a case in the certificate online support located at the following web address: http://ciscocert. It won’t happen all at once. Determining Career Options After passing the CCNA exam. If you can master those skills at your current position. To keep your certificate valid. Your CCNA is valid for three years.

and employed for a lifetime. . it is important to highlight your networking skills that pertain to the CCNA in your job and skills descriptions on your resume. Both of these certifications require you to pass multiple tests. Examining Certification Options Although passing the CCNA exam is not an easy task. continued network study and testing should feel more familiar. If you are familiar with the general concepts. focus on taking practice exams and memorizing the small details that make the exam so difficult. but it will place you ahead of other candidates. Your CCNA certificate proves that you are disciplined enough to commit to a rigorous course of study and follow through with your professional goals. The ability of our society to continually improve communication will keep you learning. The score report outlines your weaknesses. you have to wait at least five calendar days after the day of the exam to retest. As a Cisco Networking Academy alumnus. Stay motivated and sign up to take the exam again within a 30-day period of your first attempt. Even though you have listed the CCNA on your resume. discovering. When you log in to the online certification tracking tool (use the exam report to do this). Two common professional certifications are the Cisco Certified Network Professional (CCNP) and the Cisco Certified Security Professional (CCSP). This link provides specific information about professional-level certifications that you can work toward with your CCNA as the base. If You Failed the Exam If you fail your first attempt at the CCNA. It is unlikely that you will be hired simply because you have a CCNA. and Packet Tracer provides an excellent simulator for most CCNA configurations. you have access to the curriculum.38_1587131749_PostExam.qxd 208 7/28/06 9:00 AM Page 208 31 Days Before Your CCNA Exam Moran also outlines in his book that certifications such as the CCNA are part of an overall professional skill-set that you must continually enhance in order to further your IT career. but with a CCNA under your belt. remember to marvel at the innovation and creativity behind each concept you learn. be sure to view the certification progress link. it is the starting point for more advanced Cisco certifications. Summary Whether you display your certificate and update your resume or prepare to conquer the test on your second attempt. and finding a study group or online community can help you with those difficult topics. Consider your first attempt as a formal practice exam and as excellent preparation for passing the second attempt.

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197 creating. 141 numbered. 60 private.qxd 7/28/06 9:00 AM Page 211 Index SYMBOLS $ (dollar signs). 186 administrative distance (AD). 73 user protection. 69 vty. 137 network. 58-61 troubleshooting. restricting. 27 obtaining. 61-62 network addresses. 19. 197 overview. 52 addresses broadcast. 133 ? (question marks). 184 finding. 27. 73 configuring. 60 application layer OSI. 40. 39 placement. 6. 73 anemd. 29 determining. 73 IP address matching. 182 TCP/IP. 5 OSI layers. 207 Address Resolution Protocol (ARP). 133 128-bit IP version 6 (IPv6). 110 IP allocation. 29. 71 American Registry of Internet Numbers (ARIN). 9 VPNs. 6 port associations. 208 advertisement requests. 189 packets. 6 hosts. 143. 58 classes. 49 AD (administrative distance). 73 active hubs. command errors. 15 clearing/viewing. 28 IPv6. 40. 6 protocols. 53 octets. 60 MAC. 57 private. 142 guidelines. 40. 52-53 DHCP. 74 verifying. line scrolling. 74 applying. 175 vty access. 79 AND operator. 4 protocols. 57. 40 name associations. 133 ^ (caret symbols). obtaining. 58 reserved network. 30 matching. See ACLs layers. 143 access-class command. 136 finding. controlling. 9 .39_1587131749_Index. 141. 143 access-list command. 54 adaptive cut-through mode (switches). 30 A access control lists. 142 filtering options. 167-168 VLSMs. 117 allocating IP addresses. 91 advanced certifications. 58 subnetting. 19. 29. 71 binary-to-decimal conversion. 30 Internet. 142 number specifications. 29 classes (LANs). router commands. 74 traffic. determining. 17 adding CCNA to resumes. 57 broadcast. 40 named. 19 analog dial-up WAN service. 73 ACLs (access control lists). 74 wildcard masks. 107 NAT. 30 private. 51 static configuration. 27. 74. restricting. 73 extended. 91 adaptability of LANs. 74. 175 standard. 143 VTY lines.

58 DHCP. 159 cdp run command.qxd 212 7/28/06 9:00 AM Page 212 applying ACLs applying ACLs. 195 switches. 12 Boolean logic. 159 activity. 159 cdp enable command. 85 BGP (Border Gateway Protocol). 36 boot system commands. 17 Layer 2. 50 coaxial. 27 Boot ROM. 121 bridges IDs. 17 root. See MAC addresses buses. 20. 133 Carrier Sense Multiple Access/Collision Detection (CSMA/CD). 35. 57 bindings (DHCP). 159 starting. 159 SNAP. 194 WANs. 111 bits per second (bps). 127-128. 17 burned-in addresses (BIA). 30. 49 C cable modem WAN service. 11 bps (bits per second).39_1587131749_Index. 208 CDP (Cisco Discovery Protocol). improving. 129 routers. 80 cabling. 136 CCNP (Cisco Certified Network Professional). 15. 97 interfaces. 184 B backing up IOS images. 20. 159 information. 124 ScTP. 95 PPP. 122 STP. 159 central office (CO). 121-122 BECN (Backward ECN). 159 turning off. monitoring. 207 certified score reports. 127 booting routers. 65 BIA addresses. 122 types. 94 LANs. See MAC addresses BIDs (bridge IDs). 73 ARIN (American Registry of Internet Numbers). 11 broadcasts addresses. 65 BPDUs. 49-51 network functionality. viewing. 160 device details. 52 AS (autonomous system) numbers. 208 CCSP (Cisco Certified Security Professional). 145-146 avoiding loops. 121 blocking port state. 207 caret symbols (^). 27. 11 LANs. 17. 43 central processing unit (CPU). 80 authentication OSPF. 122 legacy 10 Mbps Ethernet standards. 111 LANs. 136 Catalyst 2950 switch configuration. 51 career options. 6. 122 fiber-optic. 159 CDPv2 (CDP version 2). sending. 19 ATM WAN service. 19 ARP (Address Resolution Protocol). 11 binary-to-decimal conversions. 29. clearing. 35 certificates. 43 CAM (content addressable memory). 160 enabled devices. 122-123. 195 BOOTP (Bootstrap Protocol). 137-138 bandwidth EIGRP. 205 . 39 Catalyst 1900 switch configuration. 71 Border Gateway Protocol (BGP). 160 version 2. 122 UTP. command errors.

208 Certified Security Professional (CCSP). 99 commands access-class. 159 ACLs. 196 routers. 100. 73 ACLs. 199-201 no cdp enable. 82 Cisco Certified Network Professional (CCNP). 133 debug DDR. 184 clear cdp counters command. 160 cdp enable. 197 boot system. 133 clock rate command. ignoring. 196 viewing. 43 coaxial cables. 178 clock. 134 213 . 163 isdn call interface. 60 passive-interface. 163-165 OSPF. 178 EIGRP. 159 Cisco IOS editing. troubleshooting. 165 IGRP verification. 165 RIP verification. 155. 191 CO (central office). 172 show flash. 111 ip route 0. 73 ip classless. 55 class boundaries. 17.39_1587131749_Index. 134 errors. troubleshooting. 134 configure terminal. 52 late. 36. 159 show cdp neighbors detail. 91 ping ICMP messages. 98. 37 Three-Layer Hierarchical Model. 164 no ip subnet-zero. 106-107. 177 editing. 195 configuration/backup. 159-160 HDLC encapsulation. 133 clock rate. 178 debug ip dhcp server events. 133 show. 51 remote. 159 cdp run. 191 command history. 143 access-list. 90 ip default-network. 36. 175 EIGRP verification. 163-165 OSPF. 130 show history. 51 clock command. troubleshooting.qxd 7/28/06 9:00 AM Page 213 commands CHAP (Challenge Handshake Authentication Protocol). 165 IGRP. 164-165 show access-lists. 133 extended ping. 100. 187 classes address. 29. 196 clear cdp counters. 52-53 IP addresses. 135 CLI (command-line interface). 165 RIP. 178 LANs. 171 routers booting. 122 collisions domains. 175 show cdp neighbors. 186 local. 99 client/server models. 111 debug ppp interface. 172 debug frame-relay lmi. 195 initial. verifying. 82 IOS. 57. 159 clear isdn bri command. 90 Class C Subnet chart.0. 168 history. 127 CDP activity monitoring. 39. 159-160 Discovery Protocol. 36. 178 clearing MAC addresses.0/0. 208 devices.0. 32 Layer 3 connectivity. 159 clear isdn bri. troubleshooting. 185 command-line interface (CLI). 164-165 troubleshooting. 160 show controllers. 136 switches. 160 no cdp run. 160 no debug all. configuring. 163 ip helper-address. 185 networks. 134 ip access-group.

78 switches. 164 vlan database. 137 RIP. 35 configuration files copying. 171-172 troubleshooting. 192 Frame Relay PVC. 141 commands. 163. 133 configuring ACLs. 3 serial WANs. 96-98 Frame Relay.qxd 214 7/28/06 9:00 AM Page 214 commands show interface. 149-150 IGRP. 192 verifying. 192 DHCP. 36 show vlan. 199-201 WANs. 107 NAT overload. 45. 172 undebug all. 197-199 xmodem. 163 show ip route. 137 static NAT. 39 LANs. 44 components LANs. 90. 172 show ip rip database. 163. 172 terminal no editing. 93-95 passwords. 52 networks. 134 terminal history size. 94 deleting. 172 show isdn status. 167 terminal editing. 109. 93 routers commands. 115 switches. 150 . 195 configure terminal command. 115. 91 local intranets. 110 dynamic NAT. 105-106 port security. 7 WAN data. 128 values. 130 communication CSMA/CD. 89 serial interfaces. 43. 177 show ip dhcp binding. 134 terminal monitor. 93 ISDN. 171 vty. 111 show ip interface. 101-102 IP addressing conventions. 92 interfaces bandwidth. 196 telnet. 191 static MAC addresses. 146-147 load balancing paths. 102 serial. 90 static. 99 nodes. 130 traceroute. 135 NAT. 175 show version. 177 show running config. 15 routers. 192 restoring. 108 static routes. 108 EIGRP. 100-102 VLSMs. 101 descriptions. 110 OSPF. 142 DDR. 128 restoring. 101 Ethernet. 69 login banners. 99 loopbacks. 135. 114-115 VLANs. 175 show ip protocols. 51 TCP. 195 console. 111 show ip dhcp server statistics. 91 subinterfaces. 105 initial configuration example. 149 hostnames. 127 storing. 142 named.39_1587131749_Index. 147-149 DHCP. 94. 81 service providers. 192 routes default. 134 tftpdnld. 197 extended. 126 configuration registers customizing.

74 215 convergence networks. 43 CPU (central processing unit). 117. 136 clearing. troubleshooting. 9 CPE (customer premises equipment). 172 debug frame-relay lmi command. 165 IGRP. 19 copying configuration files. 73 VTY lines with ACLs. 171 Layer 4. 193 WANs commands.39_1587131749_Index. 105 TIA/EIA-232 port connections. 77 speeds. 114-115 vlan database command. troubleshooting. 164-165 troubleshooting. 44. 114 VTP. 39-40 data link layer OSI. 163-165 OSPF. 136 Catalyst 2950. 43 digital. 113 global configuration mode. 128 core layer (three-layer hierarchical model). 45. 193 VLANs. 39 customer premises equipment (CPE). 164 . 117 trunking. 11 routers. 147-149 troubleshooting. 178 EIGRP. 125-126 VLANs. 43 physical. 45 equipment. 111 debug ppp command. 16 Frame Relay. 11 routers. 165 RIP. 161 WANs. 145 connections Frame Relay networks. 178 debug ip dhcp server events command. 78 data terminal equipment (DTE). 27 default administrative distances. 43 branch networks. 81 cabling. 43 DDR (dial-on-demand routing). 35-36 trunk. 39 D data field (IP packets). 192 passwords. 128 switch configurations. 31 data flow. 123 crosstalk. 51 control messages. 157 redundant. 39 crossover cables. 95 debug commands DDR. 17. 77 console configuring. 178 dead intervals (OSPF). 115 verifying. 128 routers boot process. 135 customizing. troubleshooting. 116 cyclic redundancy check (CRC). 43 HSSI. 37 content addressable memory (CAM). 85 switches. 193 subinterfaces. 35 CRC (cyclic redundancy check). 177 decimal and binary conversions. 44. 79 types. 43 demarcation points. 197-199 PPP encapsulation.qxd 7/28/06 9:00 AM Page 215 default administrative distances switches Catalyst 1900. 43 customizing configuration registers. 114 static commands. 16 Layer 3. 85 LANs. 43 switched circuits. 178 configuring. 32 controlling traffic. 125-126 trunk. 122-123 CSMA/CD (Carrier Sense Multiple Access/Collision Detection). 4 WANs.

111 starting/stopping. 49 DHCP (Dynamic Host Configuration Protocol). 192 host IP addresses. 97-98 topology tables. 20. 205 excluding addresses (DHCP). 16 interfaces. 64. 110. 69 . 45 digital subscribe line (DSL). 23 packets. 54 Ethernet frames. 159-160 network. 49 exterior routes (IGRP). 133 extending ACLs. 111 broadcasts. 67 bandwidth. 110 EXEC mode routers. 92 VLANs. line scrolling. 165 verifying. 77 distance vector protocols. See EIGRP enterprise servers (LANs). 40. 115 demarcation points (WANs). 70 IP address allocation. 6 dollar signs ($). 33 designs LANs. 71 message counts. 81 destination address field (IP packets). 111 configuring. 96 verifying. 90 propagating with OSPF. 9 WANs.qxd 216 7/28/06 9:00 AM Page 216 default routes default routes. 50 Layer 2 technology. 186 encrypting passwords. 183 distribution layer (three-layer hierarchical model). 16. 187 networks. 31 devices Cisco. 25 features. 20. 111 dial-on-demand routing. 133 DoS (denial-of-service) attacks. 111 processes. See DHCP dynamic NAT. 33 DSL (digital subscriber line). 43 DUAL (diffusing update algorithm).39_1587131749_Index. 22 extranet VPNs. 168 stars. 77 DSL WAN service. 30. See DDR dialer profiles. excluding. 22 configuring. 145 SNMP. 24. 101-102 LANs. 64 advanced features. 108 E editing keys/commands. 24-25 Dynamic Host Configuration Protocol. 148-149 diffusing update algorithm (DUAL). 97 configuring. 112 encapsulation PPP. 66 multiprotocol support. 96 DUAL algorithm. 24 troubleshooting. 53 internetworks. 101 static routes. 80 DTE (data terminal equipment). 106 Enhanced Interior Gateway Routing Protocol. 17 exam day. 9 DNS (Domain Name System). 134 EIGRP (Enhanced Interior Gateway Routing Protocol). 145-146 WANs. 43 denial-of-service (DoS) attacks. 74. 5 networks. 15. 24 route summaries. 70 addresses. 98 enabling PPP. 142 ping command. 24-25 digital connections (WANs). 90 deleting interface configurations. 110 bindings.

111 frames. 85 switches. 33 traffic. 7 simultaneous services. 31 flash. 83 Layer 2 frames. 44 full-duplex bandwidth. 6-7 Forward ECN (FECN). 5 TCP segments. 31 ISDN frames. 49 . 5 feasible distance field (EIGRP topology table). 24 FECN (Forward ECN). 178 217 virtual circuits. 49 networks.qxd 7/28/06 9:00 AM Page 217 hubs F failing the exam. 30. 127 storing. 95 hello packets.39_1587131749_Index. 53 HSSI (High-Speed Serial Interface). 16 IP packets. 114 HCCs (horizontal cross-connects). 79. 39 WANs. 149-150 connections. 35. 123 FDDI (Fiber Distributed Data Interface). 85 FEXT (far-end crosstalk). 186 configuring. 81 flow control. 85 inverse ARP messages. 134 horizontal cross-connects (HCCs). 5 fiber-optic cables. 52 flags field (IP packets). 78 history of commands. 80 frames Ethernet. 17 runts. 31 hello intervals. 83 Layer 2. 142 traffic. 122 fields EIGRP topology table. 85 WANs. 54 host-to-network layer. 78 header checksum field (IP packets). 52 sessions. 85. 23 hierarchy defined. 78 hubs. 43. 208 far-end crosstalk (FEXT). 5 processing. 11 port state. 85 LMIs. 6 hostnames (routers) configuring. 86 LAN connections. 128 restoring. 24 feasible successor routes. 31 Frame Relay. 15 high-bandwidth low latency WANs. obtaining. 108 hosts full-duplex bandwidth. 16 forwarding. 24 Ethernet frames. 12 fragment offset field (IP packets). 54 HDLC frames. 11 HDLC. 105 testing. 17 G-H Gbps (gigabits per second). 130 flat WAN topology. 81 High-Speed Serial Interface (HSSI). 17 interfaces. 8 files (configuration) copying. 85 forwarding DHCP broadcasts. 53 LANs. 126 filtering ACL options. 44-46. 85 verifying. 123 Fiber Distributed Data Interface (FDDI). 78 ISDN. 99 IP addresses. 121 global configuration mode (VLANs). 43.

102 serial. 100 configuring bandwidth. 80 intranet VPNs. 28 IPv6. 24 ISDN. 163 IP header length field (IP packets). 54 Internet Control Message Protocol (ICMP). 71-72.0. obtaining. 71 binary-to-decimal conversion. 70 NAT/PAT. 102 VLSMs. 185 initial router commands. 84 OSPF costs. See IGRP interior routes (IGRP). 163-165 verifying. 29. 61-62 network addresses. 64 configuring. 58-60 troubleshooting. 21 system routes. 53 octets. 94. 99 loopbacks. 29. 22 routing updates. 86 IOS File System (IFS). 32 identification field (IP packets). 60 ip classless command. 54 IEEE (Institute of Electrical and Electronics Engineers). 129-130 IOS naming conventions. 188 VLANs. 31 ip helper-address command. 167-168 VLSMs. 35. 111 IP packets. 101-102 IP addressing conventions. 113 Integrated Service Digital Network. 30 Internet. 90 IP Control Protocol (IPCP). 93 information field (EIGRP topology table). 163 . 113 interfaces configuration mode (routers). 32 IP addresses. 95 routing. 28 layer (TCP/IP). 57 private.39_1587131749_Index. 30 matching. 57. 73 IP addresses allocating. 82 ip default-network command. 22 troubleshooting. 107 NAT. 191 Interior Gateway Routing Protocol. 101 Ethernet. 135 Institute of Electrical and Electronics Engineers (IEEE).0/0 command. 70 WANs. 57 broadcast. 70-71 dividing switches into VLANs. determining. 129 ip access-group command. 129-130 names. 6 hosts. 70 types. 91 serial. 31 IDF (intermediate distribution facility). 163 images IOS. 100. 22 intermediate distribution facility (IDF). 128 IOS images. 6 internetworks DHCP. 31 ip route 0. 113 IFS (IOS File System). 69 inverse ARP messages. 22 interior routes. 128 IGRP (Interior Gateway Routing Protocol). 184 finding. 58 classes. See ISDN Inter-Switch Link (ISL). 92 exterior routes. 27 obtaining. 58 subnetting.0. 20. 40 name associations. 196 initial router configuration example. 94 deleting. 101 descriptions.qxd 218 7/28/06 9:00 AM Page 218 ICMP (Internet Control Message Protocol) I ICMP (Internet Control Message Protocol). 58 reserved network.

50 requirements. 17 local intranets. 16 data. 82 IPv6 (128-bit IP version 6). 183 traffic. 124 types. 178 ISL (Inter-Switch Link). 51 networks. 121-122 bridges. 51 wireless. 54 gateways to WANs. 15 connections.39_1587131749_Index. 43 late collisions. 83 PRI. 52 physical layers. 52 bandwidth. 16 Frame Relay. 17 Layer 2 frames. identifying. 83. 50 LAPF (Link Access Procedure for Frame Relay). 51 host traffic. 190 reference points. regulating. 79 isdn call interface command. 51 Layer 2 broadcasts. 5 . filtering. 51 topologies. 63 signals. 52-53 ARP. 55 OSI Layer 3 schemes. 134 LANs (local area networks) adaptability. 53 local machines. 146 PRI E1. 159-161 commands. 17 cabling legacy 10 Mbps Ethernet standards. 177 WANs. 122 UTP. 51-52 noise. 52 IP addresses. 54 address classes. 84 out-of-band signaling. 52 components. 54 network devices. 190 verifying. 17. 54 scalability. 54 segmenting with routers. 53. 199-201 virtual circuits. 49 NICs. 52 troubleshooting CDP. 186 repeaters.qxd 7/28/06 9:00 AM Page 219 Layer 2 frames IPCP (IP Control Protocol). 50-51 broadcasts. 54 routers. 113 The IT Career Builder’s Toolkit. 45. 186 latency LANs. 77 BRI. 30 ISDN (Integrated Service Digital Network). 51-52 communication. 50 219 expectations. 54 private addresses. 55 peer-to-peer networks. 17 functionality. 85 last mile. 147 protocols. 187 enterprise servers. 53 ports. 54 Ethernet. 78 hosts. 51 collisions. 54 OSI Layer 2 schemes. 147 frame fields. 83-84. 54 full-duplex bandwidth. 122-123 OSI Layer 1 schemes. analyzing. 55 client/server models. 146 configuring. 54 designs. 51 performance. 50. 16. 17 Layer 2 broadcasts. 121 keys. 69 manageability. 17. 122 switches content addressable memory. 123 Cisco Three-Layer Hierarchical Model. 83 interfaces. 39. 53 latency. 35. 207 J-K-L kbps (kilobits per second). 85 switches.

39. 82 link management identifiers (LMIs). 64 updates. viewing. 6 transport. 85 Link Control Protocol (LCP). 36 MANs (metropolitan-area networks). 155. 199 TCP/IP. 35 routers. 91 local area networks. 43 local machines (LANs). 69 masks (VLSMs). 86 VTP. 69 microsegmentation. 78 LCP (Link Control Protocol). 54 Media Access Control. 107 loopback interfaces.39_1587131749_Index. 12 M MAC (Media Access Control) addresses. 50. 12 leased line WAN service. 116 metropolitan-area networks (MANs). 17 models layered. 181 testing. 121 MDF (main distribution facility). 44 models. configuring. 65 distance vector protocols. See MAC addresses megabits per second (Mbps). 21 listening port state. 82 learning port state. 44 TCP/IP. 121 membership (VLANs). 54 management ports. 12 LMIs (link management identifiers). 167 troubleshooting. 102 loops avoiding. 155 Layer 4 connectivity. 53 logical topologies. 51 nonvolatile random-access (NVRAM). 6-8 three-layer hierarchical model. 181 OSI. 36 mesh. 111 inverse ARP. 171 Layer 4 connectivity. 80 LED lights (routers). 20. 21 switching.qxd 220 7/28/06 9:00 AM Page 220 Layer 3 connectivity Layer 3 connectivity testing. 182 routers. 28 application. 60 Mbps (megabits per second). 85 load balancing paths/routers. 6 port associations. 32 WANs. 160 . 51 static configuration. 70 memory content addressable. 15 login banners. 22 vector. 69 local loops. 85 link-state protocols. 5-6. 6 network access. 137 main distribution facility (MDF). 157 layers data link. 184 redundancy. 15 messages control. 157 networks. 37 Link Access Procedure for Frame Relay (LAPF). 32 counts (DHCP). 183 Linksys routers. 185 local intranets. compared. 136 finding. See LANs local collisions. 15 clearing/viewing. 3-5 physical LANs. 155 troubleshooting. 181 OSI Layer 3 connectivity. 155-157 overview. 54 WANs. 9 transport. 181 monitoring CDP activity. 49 mesh networks. 35 read-only (ROM). 9 internet.

Matthew. 185 IOS naming conventions. 17 layer. 171 types. 108 internetworks. 108 NCP (Network Control Protocol). 107 NAT (network address translation). 4 OSI management model. 29. 4 session. 27. See protocols 221 PSNs. 129 IP address association. 17 functionality. 82 network interface cards (NICs). 4 physical.qxd 7/28/06 9:00 AM Page 221 OSI (Open Source Initiative) Moran. 36 options field (IP packets). 55 Layer 3 schemes. 30 troubleshooting. 122-124 class boundaries. 57 official certificates. 60 private. 55. 17 latency. 35 O octets (IP addresses). improving. 155-156. 51-52 communication. 54 Layer 2 schemes. 61. 187 Layer 1 schemes. 4-5 LAN designs. 3 Layer 3 connectivity. 160 no debug all command. 70 IP addresses. 4 presentation. 122 subnetworks. 192 dynamic.39_1587131749_Index. 157 paths (routers). 187 collisions. 116 N names ACLs. 63 peer-to-peer. 142 images. 4 transport. 157 . 90 Class C Subnet. 110 static. 40. 79 segments. 63 network. 74. 155 Layer 4 connectivity. 9 devices (LANs). 207 multicasting (VTP). 39. 61-62 overload. 6 addresses. 49 Ethernet. 31 Organizational Unique Identifiers (OUIs). 141 numbered ACLs. 15 OSI (Open Source Initiative) layers application. 123 NICs (network interface cards). 188 NEXT (near-end crosstalk). 15 protocols. 122-123 number specifications (ACLs). 82 near-end crosstalk (NEXT). 49-52 networks access layer. 160 no cdp run command. 123 network address translation. 110. 70 signals. 207 Open Shortest Path First. 70 configuring. 164 no ip subnet-zero command. 49-52 no cdp enable command. 11 designing. 29 determining. 52 physical topology. 4 data link. ignoring. 197 NVRAM (nonvolatile random-access memory). 3 noise (LANs). 4 PDUs. 30 cabling. 99 convergence. 51 performance. See NAT Network Control Protocol (NCP). 4 model benefits. 109 packets. 60 nodes of communication. 69. See OSPF operating environments.

123 power supplies (routers). 23 IP. 33 number ranges. 95 loopback interface. 3-4 networks. 8. 91 Password Authentication Protocol (PAP). 94 priorities. 65-66 hello packets. 83 overload (NAT). See PPP port address translation (PAT). 33 passive-interface command. 44 physical layers LANs. 95 configuring. 95 interface costs. 43 MAC address associations. 105 encrypting. 137 STP states. 28 testing. 33 security. 15 out-of-band signaling. 106 privileged EXEC mode. 155-157 overview. 93. 51 per-packet load balancing. 24 hello. 79 Personal Computer Memory Card International Association (PCMCIA). 35 PDUs (protocol data units). 77 power sum near-end crosstalk (PSNEXT).qxd 222 7/28/06 9:00 AM Page 222 OSI (Open Source Initiative) layers. 155. 79 packets ACL management. 110 paths. 96 troubleshooting. 4 OSPF (Open Shortest Path First). 171 plain old telephone service (POTS). 181 TCP/IP. 22-23 OUIs (Organizational Unique Identifiers). 91 permanent virtual circuits (PVCs). propagating. 182 switches. 82 passwords console. 19-20 PCMCIA (Personal Computer Memory Card International Association). 164-165 updates. 181 peer-to-peer networks. 64. 93 databases. 168 ICMP messages. 91 packets. 28. 19-20 padding field (IP packets). 35 . 51 transport layer. 167 troubleshooting. compared. 77 ping command extended. 22 default routes. 35 phone calls (WANs).39_1587131749_Index. 4 WANs. 106 virtual terminal. 23 hello/dead intervals. 44. 78 physical topology (networks). 39 EIGRP. 70 ports demarcation points. 96 features. 31 PAP (Password Authentication Protocol). 164 authentication. 70 paths load balancing. 12. 192 P packet-switched networks (PSNs). 54 OSI. 82 PAR (positive acknowledgement and retransmission). 15 physical WAN connections. 50. 51 number assignments. 155. 94 testing. 32 Layer 3 connectivity. 31 NAT. compared. 33 POTS (plain old telephone service). 44. 182 positive acknowledgement and retransmission (PAR). 109. 77 Point-to-Point Protocol. 105 PAT (port address translation). 199 TCP/IP.

25 223 features. 145 encapsulation. 32 IGRP. 20. 208 protecting users (ACLs). 28. 20. 110 bindings. 186 networks. 145-146 enabling. 24 route summaries. 53 internetworks. 22 troubleshooting. 163-165 verifying. 83. 192 host IP addresses. 111 distance vector. 84 out-of-band signaling. 22 routing updates. 110. 67 bandwidth. 65 distance vector protocols. 145-146 LCP. 6.qxd 7/28/06 9:00 AM Page 223 protocols PPP (Point-to-Point Protocol). 9. 22 vector.39_1587131749_Index. 31 protocols application layer. 164 . 64 updates. 82 session establishment. 21 priorities OSPF. 92 defined. 71 CDP. 82 PPP. 30 RIP. 83 PRI. 146 configuring. 159-160 CHAP. 165 verifying. 64. viewing. 20. 83 interfaces. 111 starting/stopping. 24. 74 protocol data units (PDUs). 94 routes. compared. 92 exterior routes. 20. 82 session establishment. 64 advanced features. 182 ARP. 58 LANs. 181 protocol field (IP packets). 82 configured. 111 broadcasts. 91 troubleshooting. 21 system routes. 82 link-state. 190 reference points. 30 privileged EXEC mode. 71 message counts. 91 private addresses IP addresses. 70 IP address allocation. excluding. 82 network. 21 load balancing. 164-165 verifying. 96 DUAL algorithm. 183 EIGRP. 82 authentication. 190 presentation layer (OSI). 98 ICMP. 97-98 topology tables. 111 configuring. 64 configuring. 106. 4 preventing loops. 82 NCP. 133 processes (DHCP). 111 processing frames. 145-146 enabling. 111 processes. 77 BRI. 190 verifying. 17 professional certifications. 183 NCP. 190 RARP. 82. 90 Linksys support. 82. 6. 146 PRI E1. 147 protocols. 53. 30. 52 BOOTP. 97 configuring. 147 frame fields. 22 interior routes. 145 encapsulation. 30. 23 packets. 24 troubleshooting. 83-84. 82 NCP. 15 PAP. 163 ISDN. 66 multiprotocol support. 49 DHCP addresses. 82 authentication. 145-146 LCP. 64 configuring. 177 LCP.

7 TCP segments. 32 UDP. 161 TCP/IP DoS attacks. 201 RSTP. 63 BGP. 127 IOS images. 22. 164 version 1. 65 default administrative distances. 164 distance vector. 63 OSPF. 20. 33 PDUs.qxd 224 7/28/06 9:00 AM Page 224 protocols version 1. 182 redundant connections. 28 network communication. 90 Linksys support. 49 RIP (Routing Information Protocol). 182 reference points (ISDN). 129-130 routers. 64 configuring. 22. 65 version 2. 117. 171 switches. 12 SNAP. 193 messages. 143 retaking the exam. See EIGRP IGRP. 205 LANs. 11 switching loops. 5-8. 7 TCP communication. 20. 11 loops. preventing. See RIP syntax. 49-50 reported distance field (EIGRP topology table). 22. 50 RAM (random-access memory). 190 remote collisions. 64. 6. 20 EIGRP. 22-23. 208 Reverse Address Resolution Protocol (RARP). 83-84. 8 VTP. 79 Q-R question marks (?). 21 load balancing. 159 STP BIDs. 64-66 RIP. 123 PSNs (packet-switched networks). 188 OSI Layer 3. 91 troubleshooting. 33 layers. 113 configuring.39_1587131749_Index. 8 transport layer. 11 loop redundancy. 182 network convergence. 30 RF (radio frequency). 50 rings. 12. 20. 93 routing. 193 multicasting. 28 ports. 58 restoring configuration files. 202 PSNEXT (power sum near-end crosstalk). 15. 33 hosts. 93 . 6. 22. 65. 64 link-state. 28 overview. 190-191 troubleshooting. 116 modes. 116 WANs. 39. 12 RARP (Reverse Address Resolution Protocol). 4. 30 read-only memory (ROM). 19. router commands. 99 OSI. 133 radio frequency (RF). 65. 35 redundancy connections. 44. 65 version 2. 189. 164-165 verifying. 35 Rapid Spanning Tree Protocol (RSTP). 24 requirements exam day. 138 restricting vty access. 11 port states. 181 PAR. 33 sliding windows. 12 troubleshooting. 20-22. 116 switch modes. 54 reserved network IP addresses. 22 listing of. 79 PVCs (permanent virtual circuits). compared. 185 repeaters (LANs).

123 ROM (read-only memory). 192 connecting. 145 routes default. 195 boot process. 50 rollover cables. 37 CLI modes. 64 link-state. 36 packets. 65 default administrative distances. improving. 35 LANs. 99-100 NAT. enabling. 36 root bridges. 24 interior. 196 configuration commands. 63 LED lights. 19 . 22 feasible successor. 37 convergence. 37 Linksys. 97-98 exterior. 133 flash. 20-22. 195 traffic. 19-20 restoring. 35 ROM Monitor (ROMMON). 24 system. 171 VTY lines. 63 operating environments. 21 225 memory. 24 route status field (EIGRP topology table). 21 protocols BGP. 89-91 deleting. 108 initial configuration example. 188 OSI Layer 3. 112 software compatibility. 195 Cisco. 64-66 RIP. compared. 52 troubleshooting. viewing. 36 commands. 22-23. 192 Frame Relay PVC. 90 propagating with OSPF. 133 backing up. 20. 126 vty. 20-22 listing of. 178 metrics. 127-12. 128 saving. 90 functionality. 22 updates. 96 verifying. 22 configuring. 91 static configuring. 21 priorities. 19 default routes. 36 ROMMON (ROM Monitor). 91 loops avoiding. 135 interfaces. 99 internal components. 36 starting. See RIP routed protocols. 21 routing metrics. 24 routers ACL placement. customizing. 192 registers. 52 segmenting. 130 hostnames configuring. 92 verifying. See EIGRP IGRP.qxd 7/28/06 9:00 AM Page 225 routing RJ-45 connectors. 54 communication. 171 route poisoning. 74 as WAN devices. 90 EIGRP summaries. 17 paths. 164 distance vector.39_1587131749_Index. 11 route source field (EIGRP topology table). 22 poisoning. 20 EIGRP. 35-36 console TIA/EIA-232 port connections. 90 successor. 149 modes. 195 console. 175 available commands. 105 testing. 21 SNMP. 63 OSPF. 91 routing DDR. 49. 21 load balancing. 22 EXEC mode. 192 DHCP. filtering. 64. 184 preventing. 36 networks class boundaries.

100-102. 159 SNMP (Simple Network Management Protocol). 111 show ip interface command. 81 serial interfaces. 111 storage-area networks (SANs). 126 scalability (LANs). 111 show ip dhcp server statistics command. configuring. 70 stopping DHCP. See RIP RSTP (Rapid Spanning Tree Protocol). 191 service profile identifiers (SPIDs). 165 Routing Information Protocol. 190-191 troubleshooting. 36 SONET (Synchronous Optical Network). 54 ScTP (screened twisted pair). 175 EIGRP. 91 deleting. 90 static VLANs. 159 DHCP. 77 source address field (IP packets). See STP SPIDs (service profile identifiers). 84 standard ACLs. 98. 122 SIMMs (single inline memory modules). 159 show cdp neighbors command. 4 sessions PPP. 190 starting. 186 S SANs (storage-area networks). 122 security ports. 112 software compatibility (routers). 111 routers. 45. 160 show commands. 137 user protection. 126 . 163. 6. 175 show ip protocols command. 16. 165 IGRP. 7 shielded twisted pair (STP).39_1587131749_Index. 165 RIP. 163-165 OSPF. 106-107 ACLs. 172 show ip rip database command. 40. 122 show access-lists command. 108 static routes administrative distance. 84 session layer (OSI). 11 serial communication (WANs). 19. 6 SNAP (Subnetwork Access Protocol). 172 show flash command. 31 Spanning Tree Protocol. 74 WANs.qxd 226 7/28/06 9:00 AM Page 226 routing syntax. 69 storing configuration files. 8 sending BPDUs. 137 static NAT. 70 TCP. 81 segments LANs. 175 show version command. 89. 74 stars. 163 show ip route command. 195 static MAC address configuration. 134 show interface command. 130 show history command. 177 show running config command. 36 show vlan command. 39. 177 show ip dhcp binding command. 7 SMTP (Simple Mail Transfer Protocol). 115 signals (network). troubleshooting. 63 networks. 19 configuring. 15. 159 show cdp neighbors detail command. 69 saving router configurations. 35 sliding windows (TCP/IP). 172 show isdn status command. 35 single inline memory modules (SIMMs). 92 verifying. 115. 164-165 show controllers command. 163 troubleshooting. 175 show cdp command. 49 starting CDP. 201 tables. 12 runts.

182 trunks. 125-126 dividing into VLANs. 6 transport. 77 system routes (IGRP). 33 PDUs. 85 virtual circuits. improving. 11 switching loops. 16 content addressable memory. 122 straight-through cables. 28 ports. 44. 12 troubleshooting. 163 topology. 61 Subnetwork Access Protocol (SNAP). 17 backing up. 6 network access. 11. 58 eight borrowed bits. 19. 60 wildcard masks. 53 local machines. 182 network convergence. regulating. 138 static VLANs. 22 T tables routing. 117 SVCs (switched virtual circuits). 53 ports. 196 communication. 117 subnet masks VLSMs. 79 WANs. 30 subset advertisements. 58 borrowed bits with corresponding mask. 24 summary advertisements. 137 restoring. 5-6. 12 Synchronous Optical Network (SONET).qxd 7/28/06 9:00 AM Page 227 TCP/IP (Transmission Control Protocol/Internet Protocol) STP (Spanning Tree Protocol). 51 configuring Catalyst 1900. 33 sliding windows. compared. 115 switching loops. 11. 11 commands. 79 switched circuits (WANs). compared. 24 Tbps (terabits per second). 117 successor routes. 4. 182 BIDs. 136-137 microsegmentation. 51 MAC addresses. 135 customizing.39_1587131749_Index. 9 internet. 60 seven borrowed bits. 159 subnetworks. 60 two borrowed bits. 8 TCP/IP (Transmission Control Protocol/Internet Protocol) DoS attacks. 136 Catalyst 2950. preventing. 181 PAR. 121 TCP segments. 28 overview. 11 BPDUs. 137-138 BIDs. 113 STP. 7 . 33 layers. identifying. 17 network functionality. 136 clearing. 11 processing. 123 subinterfaces configuring. 11 loop redundancy. 51 host traffic. 79 switches adaptive cut-through mode. 99 OSI. 6-8 network communication. 33 hosts. 70 227 Frame Relay. 11 port states. 44-46 frames forwarding. sending. 28 application. 12. 17 port security. 59 VLSMs. 161 STP (shielded twisted pair). 187 IP addresses. 40 subnetting Class C networks. determining. 17 LANs. 150 VLANs. 182 redundant connections. 49 connections. 60 network addresses.

155 Layer 4 connectivity. 6. 115 VLANs. 164-165 RIP. 115 turning off CDP. 32 flow control. 164 unencrypted passwords. 31 traceroute command. 96 routers. 182 TCP/IP. 165 protocols. 167 OSPF. 202 serial connections. 172 terminal no editing command. 165 extended ping command. 6-7 ports. 172 DDR. 168 IGRP. 108 tftpdnld command. 7 troubleshooting. 161 switches. 7 TCP communication. 160 EIGRP route summaries. 8 transport layer. 199 OSPF. 171 OSI model. 97 type of service field (IP packets). 157 OSI model. 177 trunk configuring. 9 time division multiplexing (TDM). 8 undebug all command. 178 ISDNs. 171 routing. 163-164. 199-201 WANs Frame Relay. 73 filtering. 167 terabits per second (Tbps).qxd 228 7/28/06 9:00 AM Page 228 TCP/IP (Transmission Control Protocol/Internet Protocol) TCP communication. 8 sessions. 183 logical. 134 terminal history size command. 155-156. 15 tables. 106 unshielded twisted pair (UTP). 199-201 Layer 3 connectivity. 122-123. 165 IP addresses. 22 OSPF. 4 ports. 81 three-layer hierarchical model. 193 connections. 22-23 routes. See also testing commands. 130 three-layer designs (WANs). 167-168 LANs CDP. 31 U-V UDP (User Datagram Protocol). 163 STP. 161. 91 . 52 hosts. 7 segments. See TCP/IP transport layer OSI. 159-161 commands. 165 routers. 201 tables. 171-172 traffic controlling. 178 DoS attacks. 81 time to live field (IP packets). 194 updates link-state protocols. 81 telnet command. 33 EIGRP. 5 topologies LANs. 161 trunk connections.39_1587131749_Index. 177 protocols. 121 terminal editing command. 161 VLANs. 15 physical. 24 total length field (IP packets). See also troubleshooting Layer 3 connectivity. 31 Token Ring Layer 2 technology. 32 TDM (time division multiplexing). 134 terminal monitor command. 134 testing. 53 Transmission Control Protocol/Internet Protocol. 171 networks.

114-115 VLAN Trunking Protocol. 193 multicasting. 74. 61 VPNs (virtual private networks). 43 speeds. 117. 43 provider central office. 199-201 trunking. See VCs Virtual LANs. See VTP VLANs (Virtual LANs). 69. 192 lines. 82 communication service providers. 43 branch networks. 149 EIGRP. 133 configured protocols. 136 memory. 145 connections. 116 modes. 105 vlan database command. 110 OSPF priorities. 45 equipment. 31 vertical cross-connects (VCCs). See VLANs virtual private networks (VPNs). 130 MAC addresses. 122-123. 161. 74 W WANs (wide-area networks). 113 global configuration mode. 177 NAT configurations. 197-199 PPP encapsulation. 43 switched circuits. 90 routing protocols. 114 static commands.39_1587131749_Index. 8 users. 143 configuring. 36 NAT packets. 69. 117 verifying. 175 DDR configuration. 85 LANs. 193 static. 77 . 77 VTP (VLAN Trunking Protocol). 159 Cisco neighboring devices. 113 configuring. 60. 193 multicasting. 79 Frame Relay networks. 114-115 version field (IP packets). restricting. controlling. 110 virtual circuits. 43. 114 229 customizing. 92 DHCP. 77 virtual terminal passwords. 117 messages. 51 verifying ACLs. 147. 44. 150. 93 IP address subnets. 54 VCs (virtual circuits). 193 messages. 116 modes. See VLSMs VCCs (vertical cross-connects). 43 digital. 69 Cisco HDLC encapsulation. 79 types. 54 viewing cdp-enabled devices. 115 dividing switches into. 114-115 vlan database command. 115 VTP configuring. 81 cabling. 159 commands. 111 flash. 163-164 VLAN configuration. 43 HSSI. 193 subinterfaces. 70 overview. 94 routes. configuring. 74 UTP (unshielded twisted pair). 78 configuring commands.qxd 7/28/06 9:00 AM Page 229 WANs (wide-area networks) User Datagram Protocol (UDP). 92 interfaces. 113 membership. 116 vty access. 113 configuring. 43 demarcation points. 116 switch modes. 116 VLSMs (variable-length subnet masks). 194 variable-length subnet masks. 70 features. 70 troubleshooting. 116 switch modes. 178 ISDNs. 116 deleting. 98 Frame Relay. protecting.

84 out-of-band signaling. 146 PRI E1. 147 frame fields. configuring. 78 high-bandwidth/low latency. 202 routers connecting.25 WAN service. configuring. 145-146 LCP. 190 protocols. 83 reference points. 145 security. 81 encapsulation. 85 frames. 86 LAN connections. 85 configuring. 147-149 defined. 40 WLANs (wireless LANs). 81 Frame Relay.qxd 230 7/28/06 9:00 AM Page 230 WANs (wide-area networks) data communication. 149-150 connections. 36 as WAN devices. 79-80 three-layer designs. 130 YAOMC (Yet Another OSI Model Chart). 82 NCP. 80 xmodem command. 177-178 websites certificate online support. 3 wildcard masks ACLs. 73 subnet masks. 44 physical connections. 83 PRI. 81 troubleshooting. 147 protocols. 83 interfaces. 50 X-Y-Z X. 85 LMIs. 45. configuring. 45. 145-146 enabling. 82. 85 virtual circuits. 3-4 .39_1587131749_Index. 207 Wikipedia. 145 encapsulation. 81 services. compared. 146 configuring. 78 PPP authentication. 69 designing. 44. 82 session establishment. 85 switches. 189. 83-84 verifying. 77 physical layers. 44-46. See WANs Wikipedia website. 186 flat topology. 147 packet-switched networks. 44 phone calls. 78 DDR. 44 gateways to LANs. 81 serial communication. 85 inverse ARP messages. 44 data link layers. 3 wide-area networks. 81 internetworks. 71-72. 80 ISDN BRI. 44.

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