Cisco LAN Switching Kennedy Clark, CCIE No. 2175, CCSI Kevin Hamilton, CCSI Cisco Press Cisco Press 800 East 96th Street Indianapolis, IN 46240 USA ii Cisco LAN Switching Kennedy Clark, Kevin Hamilton Copyright© 2001 Cisco Press 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 8 9 10 11 12 Library of Congress Cataloging-in-Publication Number: 99-61692 ISBN: 1-57870-094-9 Eighth Printing November 2004 Warning and Disclaimer This book is designed to provide information about Cisco LAN switching. 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For more information, please contact: U.S. Corporate and Government Sales 1-800-382-3419 [email protected] For sales outside of the U.S. please contact: International Sales 1-317-581-3793 [email protected] iii Publisher John Wait Executive Editor John Kane Cisco Systems Management Michael Hakkert Tom Geitner William Warren Managing Editor Patrick Kanouse Acquisitions Editor Brett Bartow Development Editor Christopher Cleveland Project Editor Caroline Wise Copy Editor Kelli Brooks Technical Editors Tom Nosella, Jennifer DeHaven Carroll, Phil Bourgeois, Merwyn Andrade, Stuart Hamilton Team Coordinator Amy Lewis Book Designer Gina Rexrode Cover Designer Louisa Adair Production Team Steve Gifford Indexer Tim Wright iv About the Authors Kennedy Clark is CCIE No. 2175 and the founder of Remote Technology Solutions (RTS), a company that offers network-related products and services. RTS’ main product is AutoVerify, a tool that allows real-time grading and feedback of hands-on labs in such fields as training, e-learning, and testing. Kennedy also works as a consultant specializing in network architecture and design. As a former certified Cisco Systems instructor, he was one of the original Catalyst instructors for Cisco. Over the years, Kennedy has taught a wide variety of switching classes and been involved in the design and implementation of many large, switched backbones. Although he loves “technical stuff,” his favorite activity is spending time with this wife Debra, daughter Madison, and son Mason. Kevin Hamilton (RCIE # 11, RCSI # 11) is a certified Cisco Systems instructor and is seniorinstructor for Riverstone Networks where he delivers courses and consults on network topics such as LAN switching, MPLS, and routing. Prior to Riverstone, Kevin was an instructor/consultant for Mentor Technologies (formerly Chesapeake Computer Consultants) where he focused on Catalyst, ATM, and network security technologies. Kevin obtained a degree in electrical engineering from Pennsylvania State University. About the Technical Reviewers Merwyn Andrade works as a Senior Technical Marketing Engineer for Cisco Systems, Inc. in San Jose, California. Merwyn works closely with Cisco engineering and customers on features running across Cisco switches as well as enhancements to minimizing downtime and convergence and improving network availability. Merwyn also has a patent in progress in this area. Prior to Cisco, Merwyn worked with the Bombay Stock Exchange and as a Network Consultant with HCL-Hewlett Packard in India. He is an Industrial Electronics Engineer from Bombay, India. Philip B. Bourgeois has been in the computer industry for fifteen years, spending seven years as a networking specialist with IBM and the past five years as a Senior Systems Engineer with Cisco Systems. Phil is experienced in the design and implementation of large IP and multiprotocol networks, encompassing complex wide area network designs and campus local area networks. Phil is a networking consultant to the largest commercial enterprises in the northeast area, including insurance, the health care industry, aerospace, pharmaceuticals, casino/gaming industry, state government agencies, and higher education. His current position is as a Consulting Systems Engineer with a specialty focus in high-speed LAN switching and ATM network design projects. Jennifer DeHaven Carroll is a Principal Consultant for International Network Services. She is CCIE number 1402. She earned her Bachelor of Science degree in Computer Science from University of California, Santa Barbara. In the past 11 years, Jennifer has planned, designed, and implemented many networks, utilizing both Layer 2 and Layer 3 techniques. She has also developed and taught many theory and Cisco implementation classes on various networking technologies. Stuart Hamilton is the Senior Manager of Enterprise Network Design at Cisco Systems where he leads a team of engineers focused on the design requirements of enterprise customers. Stuart is a CCIE and joined Cisco in 1992 where, as a System Engineer and Consulting Engineer, worked closely in the field with numerous customers on large scale network designs and implementations. Early in Stuart’s 14 years of experience he held various technical design and engineering roles at Bell Northern Research, Northern Telecom (now Nortel Networks), and Cognos Incorporated. Tom Nosella is Manager of Network Design Engineering for Cisco’s Enterprise Line of Business. Tom and his team of network design engineers provide direction and expertise in enterprise network design for both Cisco’s worldwide systems engineers and Cisco’s enterprise customer base. Tom is a CCIE and has six years of experience in managing and designing large data networks for customers within the enterprise and service provider area. Tom joined Cisco Systems from Bell Canada where he led a team of network engineers providing outsourced network management services for large enterprise customers. v Dedications To my wife, Debbie, for being the most supportive, understanding, patient, and loving partner a person could ever ask for. And, to God, for giving me the ability, gifts, and privilege to work in such an exciting and fulfilling career. -Kennedy To my wife, Emily, the true author in our family, who taught me the joy of communication through the printed page and who now has many romantic evenings due in appreciation for the ones neglected. And to my four boys, Jay, Scott, Alex and Caleb, who endured with exceeding patience the hours dad locked himself in a quiet room instead of playing ball and camping. -Kevin vi Acknowledgments Kennedy Clark: An avid reader of all things nerdy, I have always taken acknowledgements and dedications fairly lightly. Having now been through the book-writing process myself, I can assure you that this will never be the case again. Writing a book (especially one on technology that is as fast-moving as switching) is an incredibly demanding process that warrants a huge number of “thank yous.” In the brief space I have here, I would like to express appreci- ation to a small number of the people involved in this project. First, I would like to thank Kevin Hamilton, my co- author. Kevin was willing to jump into a project that had almost been left for dead because I was feeling completely overwhelmed by the staggering amount of work it involved. I would like to thank Radia Perlman for reading the e- mails and Spanning Tree chapters of an “unknown author.” Also, the people at Cisco Press have been wonderful to work with (I would encourage other authors to check them out). Chris Cleveland and Brett Bartow deserve special mention. There are many people at Cisco to thank... Jon Crawfurd for giving a young NetWare guy a chance with router technology. Stuart Hamilton for taking this project under his wing. Merwyn Andrade for being the switching genius I someday hope to be. Tom Nosella for sticking with the project through its entirety. I owe many thanks to the people at Chesapeake Computer Consultants. I would especially like to thank Tim Brown for teaching me one of my first network courses and remaining a faithful friend and mentor. Also, Tom Van Meter for showing me the ropes with ATM. Finally, a very special thanks to my wife for her never-ending love and encouragement. And, to God, for giving me the ability, gifts, and privilege to work in such an exciting and fulfilling career. Kevin Hamilton: A project of this magnitude reflects the hard work of many individuals beyond myself. Most notably, Kennedy. He repeatedly amazes me with his ability to not only understand minute details for a vast array of subjects (many of which are Catalyst related), but to reiterate them without reference to written materials months and even years past the time when he is exposed to the point. His keen insights to networking and unique methods of communicating them consistently challenge me to greater professional depths. I, therefore, thank Kennedy for the opportunity to join him in this endeavor, and for the knowledge I gained as a result of sharing ink with him. I also must thank the staff and instructors at Chesapeake Computer Consultants for their continuous inspiration and support as we at times felt discouraged thinking we would never write the last page. And Tim Brown, who taught me that technology can be funny. And lastly, the staff at Cisco Press. Brett Bartow and Chris Cleveland must espe- cially be commended for their direction and vision in this project. They worked hard at keeping us focused and motivated. I truly believe that without their guidance, we could never have produced this book on our own. vii Contents at a Glance Part I Foundational Issues 3 Chapter 1 Desktop Technologies 5 Chapter 2 Segmenting LANs 35 Chapter 3 Bridging Technologies 55 Chapter 4 Configuring the Catalyst 83 Chapter 5 VLANs 113 Part II Spanning Tree 157 Chapter 6 Understanding Spanning Tree 159 Chapter 7 Advanced Spanning Tree 205 Part III Trunking 299 Chapter 8 Trunking Technologies and Applications 301 Chapter 9 Trunking with LAN Emulation 345 Chapter 10 Trunking with Multiprotocol Over ATM 415 Part IV Advanced Features 449 Chapter 11 Layer 3 Switching 451 Chapter 12 VLAN Trunking Protocol 537 Chapter 13 Multicast and Broadcast Services 573 Part V Real-World Campus Design and Implementation 601 Chapter 14 Campus Design Models 603 Chapter 15 Campus Design Implementation 643 Chapter 16 Troubleshooting 699 Chapter 17 Case Studies: Implementing Switches 717 Part V Real-World Campus Design and Implementation 601 Chapter 14 Campus Design Models 603 Part VI Appendix 841 Appendix A Answers to End of Chapter Exercises 843 Index 892 viii Contents Part I Foundational Issues 3 Chapter 1 Desktop Technologies 5 Legacy Ethernet 5 Carrier Sense with Multiple Access with Collision Detection (CSMA/CD) 6 Addressing in Ethernet 7 LAN Frames 10 Ethernet SlotTimes 11 Ethernet Frame Rates/Performance 13 Fast Ethernet 14 Full-Duplex and Half-Duplex Support 15 Autonegotiation 16 100BaseTX 17 100BaseT4 17 100BaseT2 17 100BaseFX 18 Media-Independent Interface (MII) 19 Network Diameter (Designing with Repeaters in a 100BaseX Network) 19 Practical Considerations 23 Gigabit Ethernet 24 Gigabit Architecture 25 Full-Duplex and Half-Duplex Support 27 Gigabit Media Options 27 Token Ring 29 Token Ring Operations 29 Token Ring Components 31 Summary 32 Review Questions 32 Chapter 2 Segmenting LANs 35 Why Segment LANs? 35 Segmenting LANs with Repeaters 37 Shared Bandwidth 39 Number of Stations per Segment 39 End-to-End Distance 40 Segmenting LANs with Bridges 42 ix Segmenting LANs with Routers 46 Segmenting LANs with Switches 48 Summary 50 Review Questions 51 Chapter 3 Bridging Technologies 55 Transparent Bridging 55 Learning 57 Flooding 58 Filtering 58 Forwarding 59 Aging 59 Switching Modes 60 Store-and-Forward Switching 62 Cut-Through Switching 63 Fragment-Free Switching 63 Token Ring Bridging 64 Source-Route Bridging 64 Source-Route Transparent Bridging 66 Source-Route Translational Bridging 69 Token Ring Switching 73 Token Ring Concentrator Relay Function (TrCRF) 73 Token Ring Bridge Relay Function (TrBRF) 74 Source-Route Switching 75 Duplicate Ring Protocol (DRiP) 77 Ethernet or Token Ring? 77 Migrating Token Ring to Ethernet 78 Summary 79 Review Questions 79 Chapter 4 Configuring the Catalyst 83 Catalyst 5000/6000 CLI Syntax Conventions 84 Catalyst 5000 Configuration Methods 84 Console Configuration 86 Telnet Configuration 87 TFTP Configuration 88