Cisco Press 201 West 103rd Street Indianapolis, IN 46290 USA Cisco Press IP Telephony Self-Study Cisco DQOS Exam Certification Guide Wendell Odom, CCIE No. 1624 Michael J. Cavanaugh, CCIE No. 4516 DQOS.book Page i Wednesday, July 16, 2003 4:06 PM ii IP Telephony Self-Study Cisco DQOS Exam Certification Guide Wendell Odom and Michael J. Cavanaugh Copyright © 2004 Cisco Systems, Inc. Cisco Press logo is a trademark of Cisco Systems, Inc. Published by: Cisco Press 201 West 103rd Street Indianapolis, IN 46290 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 Library of Congress Cataloging-in-Publication Number: 2001097407 ISBN: 1-58720-058-9 First Printing July 2003 Warning and Disclaimer This book is designed to provide information about quality of service (QoS) for the Cisco Catalyst switch platform. 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. Trademark Acknowledgments All terms mentioned in this book that are known to be trademarks or service marks have been appropriately capitalized. Cisco Press or Cisco Systems, Inc. cannot attest to the accuracy of this information. Use of a term in this book should not be regarded as affecting the validity of any trademark or service mark. These materials have been reproduced by Pearson Technology Group with the permission of Cisco Systems Inc. COPYRIGHT © 2003 CISCO SYSTEMS, INC. ALL RIGHTS RESERVED. Feedback Information At Cisco Press, our goal is to create in-depth technical books of the highest quality and value. Each book is crafted with care and precision, undergoing rigorous development that involves the unique expertise of members from the profes- sional technical community. Readers’ feedback is a natural continuation of this process. If you have any comments regarding how we could improve the quality of this book, or otherwise alter it to better suit your needs, you can contact us through e-mail at feedback@ciscopress.com. Please make sure to include the book title and ISBN in your message. We greatly appreciate your assistance. DQOS.book Page ii Wednesday, July 16, 2003 4:06 PM iii Publisher John Wait Editor-In-Chief John Kane Cisco Representative Anthony Wolfenden Cisco Press Program Manager Sonia Torres Chavez Cisco Marketing Communications Scott Miller Manager Cisco Marketing Program Manager Edie Quiroz Executive Editor Brett Bartow Production Manager Patrick Kanouse Development Editor Ginny Bess Munroe Copy Editor Keith Cline Technical Editors Frank Knox and Tim Szigeti Team Coordinator Tammi Ross Book Designer Gina Rexrode Cover Designer Louisa Klucznik Compositor Octal Publishing, Inc. Indexer Larry Sweazy Proofreader Missy Pluta DQOS.book Page iii Wednesday, July 16, 2003 4:06 PM iv About the Authors Wendell Odom, CCIE No. 1624, is a senior instructor with Skyline Computer (www.skylinecomputer.com). Wendell has worked in the networking arena for 20 years, working in pre- and post-sales technical consulting, teaching, and course development. He has authored portions of over 12 courses, including topics such as IP routing, MPLS, Cisco WAN switches, SNA protocols, and LAN troubleshooting. He is author of the bestselling Cisco Press title CCNA Exam Certification Guide . Michael J. Cavanaugh, CCIE No. 4516 , has been in the networking industry for over 17 years. His employment with such companies as General Electric, Cisco Systems, and Bellsouth Communication Systems has allowed him to stay at the forefront of technology and hold leading edge certifications. His current focus is AVVID implementations, providing convergance consulting, professional services, and technical support. Michael’s passion is learning the practical applica- tions of new technologies and sharing knowledge with fellow engineers. About the Technical Reviewers Frank Knox, CCIE No. 3698 (Routing & Switching and SNA-IP) , is currently the chief technology officer for Skyline Computer Corporation. Frank also participates in the business as a consultant and instructor in the areas of design, implementation, and customer training for all aspects of networking, including IP telephony. Frank has more than 35 years of networking experience with IBM, GTE, and Skyline Computer. During that time, he has worked in field service and support, product planning, education, and management. In addition, he has developed and taught several courses for the University of Dallas (Telecommunications MBA program). Frank has a master’s degree in telecommuni- cations from Pace University. Tim Szigeti, CCIE No. 9794 , is a member of the Enterprise Solutions Engineering design team at Cisco Systems. In this role, he works closely with customers and engineering to develop advanced, scalable, and tested solutions for the Cisco AVVID Network Infrastructure (CANI). Prior to this, he was performing technical marketing and product man- agement within the Enterprise Management Business Unit, specializing in QoS Management. Dedications Wendell Odom: Mike Zanotto, or Mike Z as he’s known throughout California and the world, has had a significant impact on my personal involvement with this book. Mike let me start our company’s efforts to teach DQOS classes back in 2001—even when it didn’t look like the class would be that popular—just because it might turn into more. Well, it turned out to be a great move for Skyline Computer, and for me. Mike’s willingness to take chances like that has had a lot to do with Skyline’s success over the years. As my boss, he makes it possible for me to have time to write without totally destroying all of my time for my family! As a friend, he helps keep me laughing, and not take the networking world too seriously. Mike Z, thanks for helping make this book possible! Michael J. Cavanaugh: I would like to dedicate this book to my lovely wife KC and beautiful daughter Caitlin for their love and support through the years, but especially as I took my first steps in writing. I would like to thank Wendell Odom for giving me the opportunity to co-author this book. It has been an exciting and challenging experience. I would also like to thank all of the people at Cisco Press and the technical editors that made this book a reality. DQOS.book Page iv Wednesday, July 16, 2003 4:06 PM v Acknowledgments My uncle Eulie used to work in the meat market in the small town I grew up in. I loved hot dogs—but he’d never let me see how they made them!! He always told me that if I liked them, then I really didn’t want to know how they were made! This book has taken a while to complete, with several distractions from all directions. The path we all took to complete this book was a little messy—like making hot dogs, I’m sure—and two individuals in particular made this book possible in spite of the interruptions and diversions. Michael Cavanaugh, my co-author, worked tirelessly to finish several key components of the book. His vast practical skills have improved the book tremendously. Michael got to do some of the more challenging parts of the book, and under duress—Michael, thanks so much for making the difference! Ginny Bess, the development editor for this book, got the opportunity to jump into the mix mid-project. While many people contribute to the success of any book, the development editor is the author’s main contact for submitting and editing the content. When Gin came on board, we didn’t miss a beat, with book development running very smoothly. When job responsibilities required a change in development editors mid-stream, we knew it was a risk, but Ginny came through and did an excellent job. Chris Cleveland started the book development and gave us guidance as needed. Chris’s primary focus is to make the author’s life easier, and as always, he succeeded. Thanks for the usual stellar job! Brett Bartow, executive editor for this project, happens to be an avid baseball fan, as am I. Brett’s job requires that he be able to “hit major league curveballs”—for you non-baseball fans, that means he can hit a moving target with the best of them. Once again, Brett, your steady hand throughout the entire writing and editing process helped make this project a success. Thanks for staying on top of the positioning and business issues relating to the book. Moreso than for most books, this book required some extra effort on the figures in the book. Amy Parker created several new icons for this book, with these icons representing some relatively complex concepts. Amy came through for us, taking my general comments and rough ideas, in some cases refining them, and in others coming up with whole new (and much better) ways to represent the concepts. Thanks much! Finally, the production side of the business does not get as much notice, because the author (me) who writes these acknowl- edgements seldom works directly with them. Over the last few years, I’ve gotten to see more of their work, and believe me, I really do have the easy part of the job. I deliver Word documents and Powerpoint (rough) drawings—and all production does is somehow make this wonderfully polished book appear. Thanks for making me look good again, and again, and again! As usual, the technical editors deserve most of the credit for making the content of this book robust and complete. For this edition, Tim Szigeti and Frank Knox did the technical editing. Tim’s job requires that he help define and evangelize what Cisco views as “best practices” for QoS deployments. His practical experience and ability to communicate well helped us make this book a much more practical reference. Tim, thanks for your work and your patience in helping us resolve the occa- sional difference between what’s on the exams and in the QoS courses, as compared with Cisco’s suggested best practices! Frank Knox, dual CCIE and someone I personally credit with getting me interested in the training world 15 years ago, also worked hard on the technical editing process. Frank’s no-nonsense approach to editing, with an occasional nonsen- sical joke thrown in, both helped the manuscript improve, and kept me a little saner during my re-work of the chapters based on his comments. Thanks to you both for making this book so much better! Ultimately, Michael and I are most responsible for the contents of the book, so any errors you find are certainly our fault. However, if you do think you found an error, the best way to get in touch to report the error is to go to www.ciscopress.com, click on the “Contact Us” tab, and fill in the form. When it’s something that needs a look from the authors, the information gets to us expediently. If it’s a problem that can be handled by the publisher, they can get to it even more quickly! Finally, no section called acknowledgments could be complete without acknowledging a few others. My wife, Kris, regularly takes on all the load for practical stuff at home, instead of the usual majority of the load, when a book project comes down to the wire. This time around, we had three books on similar deadlines. As always, Kris, thanks for helping me when the timing is tight! And ultimately, in this book effort and all else, I must acknowledge Jesus Christ, my friend, intercessor, and savior! DQOS.book Page v Wednesday, July 16, 2003 4:06 PM vi Contents at a Glance Foreword xvii Introduction xviii Chapter 1 QoS Overview 3 Chapter 2 QoS Tools and Architectures 83 Chapter 3 Classification and Marking 155 Chapter 4 Congestion Management 233 Chapter 5 Traffic Policing and Shaping 319 Chapter 6 Congestion Avoidance Through Drop Policies 425 Chapter 7 Link-Efficiency Tools 479 Chapter 8 Call Admission Control and QoS Signaling 541 Chapter 9 Management Tools and QoS Design 657 Chapter 10 LAN QoS 687 Appendix A Answers to the “Do I Know This Already?” Quizzes and Q&A Sections 763 Appendix B Topics on the CCIP QoS Exam 831 Index 883 DQOS.book Page vi Wednesday, July 16, 2003 4:06 PM vii Table of Contents Foreword xvii Introduction xviii Chapter 1 QoS Overview 3 “Do I Know This Already?” Quiz 3 QoS: Tuning Bandwidth, Delay, Jitter, and Loss Questions 4 Traffic Characteristics of Voice, Video, and Data Questions 5 Foundation Topics 6 QoS: Tuning Bandwidth, Delay, Jitter, and Loss 7 Bandwidth 9 The clock rate Command Versus the bandwidth Command 11 QoS Tools That Affect Bandwidth 11 Delay 13 Serialization Delay 14 Propagation Delay 16 Queuing Delay 18 Forwarding Delay 20 Shaping Delay 20 Network Delay 22 Delay Summary 23 QoS Tools That Affect Delay 24 Jitter 27 QoS Tools That Affect Jitter 28 Loss 29 QoS Tools That Affect Loss 29 Summary: QoS Characteristics: Bandwidth, Delay, Jitter, and Loss 32 Traffic Characteristics of Voice, Video, and Data 32 Voice Traffic Characteristics 33 Voice Basics 33 Voice Bandwidth Considerations 36 Voice Delay Considerations 39 Voice Jitter Considerations 48 Voice Loss Considerations 49 Video Traffic Characteristics 52 Video Basics 52 Video Bandwidth Considerations 54 Video Delay Considerations 55 Video Jitter Considerations 56 Video Loss Considerations 57 Comparing Voice and Video: Summary 57 DQOS.book Page vii Wednesday, July 16, 2003 4:06 PM viii Data Traffic Characteristics 57 IP Data Basics 58 Data Bandwidth Considerations 63 Data Delay Considerations 64 Data Jitter Considerations 64 Data Loss Considerations 65 Comparing Voice, Video, and Data: Summary 66 Foundation Summary 67 Q&A 79 Chapter 2 QoS Tools and Architectures 83 “Do I Know This Already?” Quiz 83 QoS Tools Questions 84 Differentiated Services Questions 85 Integrated Services Questions 85 Foundation Topics 86 Introduction to IOS QoS Tools 86 Classification and Marking 86 Classification and Marking Tools 89 Queuing 90 Queuing Tools 91 Shaping and Policing 93 Shaping and Policing Tools 95 Congestion Avoidance 96 Congestion-Avoidance Tools 97 Link Efficiency 97 Link-Efficiency Tools: Summary 99 Call Admission Control and RSVP 100 CAC Tools 101 Management Tools 102 Summary 103 The Good-Old Common Sense QoS Model 104 GOCS Flow-Based QoS 105 GOCS Class-Based QoS 108 Classification and Marking at the Edge 109 The Differentiated Services QoS Model 114 DiffServ Specifications and Terminology 114 DiffServ Per-Hop Behaviors 119 The Class Selector PHB and DSCP Values 121 The Assured Forwarding PHB and DSCP Values 125 The Expedited Forwarding PHB and DSCP Values 128 DQOS.book Page viii Wednesday, July 16, 2003 4:06 PM ix DiffServ Classifiers and Traffic Conditioners 129 The Integrated Services QoS Model 133 Foundation Summary 137 Q&A 152 Chapter 3 Classification and Marking 155 “Do I Know This Already?” Quiz Questions 155 Classification and Marking Concepts Questions 156 CAR, PBR, and CB Marking Questions 157 Foundation Topics 158 Classification and Marking Concepts 158 Classification 158 Marking 162 IP Header QoS Fields: Precedence and DSCP 163 LAN Class of Service (CoS) 166 Other Marking Fields 168 Summary of Marking Fields 168 Classification and Marking Design Choices 170 Classification and Marking Tools 175 Class-Based Marking (CB Marking) 175 Network-Based Application Recognition (NBAR) 185 CB Marking show Commands 189 CB Marking Summary 193 Committed Access Rate (CAR) 193 CAR Marking Summary 200 Policy-Based Routing (PBR) 201 PBR Marking Summary 207 VoIP Dial Peer 207 VoIP Dial-Peer Summary 214 Summary of Classification and Marking QoS Features 214 Foundation Summary 217 Q&A 229 Chapter 4 Congestion Management 233 “Do I Know This Already?” Quiz 233 Queuing Concepts Questions 234 WFQ and IP RTP Priority Questions 234 CBWFQ and LLQ Questions 235 Comparing Queuing Options Questions 235 DQOS.book Page ix Wednesday, July 16, 2003 4:06 PM x Foundation Topics 236 Queuing Concepts 236 Output Queues, TX Rings, and TX Queues 239 Queuing on Interfaces Versus Subinterfaces and Virtual Circuits (VCs) 245 Summary of Queuing Concepts 248 Queuing Tools 248 FIFO Queuing 249 Priority Queuing 251 Custom Queuing 254 Weighted Fair Queuing (WFQ) 257 WFQ Classification 258 WFQ Scheduler: The Net Effect 259 WFQ Scheduling: The Process 260 WFQ Drop Policy, Number of Queues, and Queue Lengths 264 WFQ Configuration 266 WFQ Summary 271 Class-Based WFQ (CBWFQ) 272 CBWFQ Configuration 275 CBWFQ Summary 287 Low Latency Queuing (LLQ) 288 LLQ Configuration 290 LLQ with More Than One Priority Queue 295 IP RTP Priority 296 IP RTP Priority Configuration 297 Summary of Queuing Tool Features 299 Foundation Summary 301 Q&A 313 Conceptual Questions 313 Priority Queuing and Custom Queuing 313 WFQ 314 CBWFQ, LLQ, IP RTP Priority 314 Comparing Queuing Tool Options 316 Chapter 5 Traffic Policing and Shaping 319 “Do I Know This Already?” Quiz 319 Shaping and Policing Concepts Questions 320 Policing with CAR and CB Policer Questions 320 Shaping with FRTS, GTS, DTS, and CB Shaping 321 DQOS.book Page x Wednesday, July 16, 2003 4:06 PM [...]... Abbreviation and Number Building Scalable Cisco Internetworks Building Scalable Cisco Internetworks (BSCI) 642-801 Configuring BGP on Cisco Routers Border Gateway Protocol (BGP) 642-661 Implementing Cisco QoS QOS 642-641 Implementing Cisco MPLS Multiprotocol Label Switching (MPLS) 640-910 The Cisco QOS Exam 642-601 Like the DQOS exam and many other Cisco exams, Cisco lists the exam topics on their web... hands-on experience Cisco Systems has created an authorized Cisco Learning Partner program to provide you with the most highly qualified instruction and invaluable hands-on experience in lab and simulation environments To learn more about Cisco Learning Partner programs available in your area, please go to www .cisco. com/go/training The books Cisco Press creates in partnership with Cisco Systems will... attaining Cisco certifications Channel Partner IP Telephony Technology Specializations The most popular reason for taking the DQOS exam relates to the Cisco Channel Partner program Cisco calls their resellers and services partners Channel Partners The way the program works is that Cisco moves more than 90 percent of their product sales, in dollar volumes, through their Channel Partners Thus, Cisco is... Required Cisco IP Telephony Design Specialist CCDAa Enterprise Voice over Data Design Exam (9E0-411 EVODD) Deploying Quality of Service in Enterprise Networks Exam (9E0-601 DQOS) Cisco IP Telephony Support Specialist CCNP* Cisco Voice Over Frame Relay, ATM, and IP Exam (9E0-431 CVOICE) Cisco IP Telephony Exam (9E0-402 CIPT) Deploying Quality of Service in Enterprise Networks Exam (9E0-601 DQOS) Cisco. .. goals, Cisco has retained both courses DQOS.book Page xxvii Wednesday, July 16, 2003 4:06 PM xxvii Because the DQOS course is more focused on the application of QoS for voice, Cisco chose the DQOS exam for the CQS and Channel Partner Telephony certifications Similarly, when Cisco created the Cisco Certified Internetwork Professional (CCIP) certification, they chose to use the QOS 642-641 exam Cisco designed... enable high profile, mission-critical traffic to perform at an optimal level This book was developed in cooperation with the Cisco Internet Learning Solutions Group Cisco Press books are the only self-study books authorized by Cisco for CCIP and IP Telephony exam preparation Cisco and Cisco Press present this material in text-based format to provide another learning vehicle for our customers and the broader... Engineer CQS Exams/Certifications Required by Channel Partner Role, but Not by CQS Cisco IP Telephony Design Specialist Cisco Product Solutions Essentials IPT Exam v2.0 (SE0-286) IP Telephony Solutions Exam (SE0-261) Field Engineer 1 Cisco IP Telephony Support Specialist Telephony Fundamentals Exam (SE0-263) Operations Specialist Cisco IP Telephony Operations Specialist None As you can see from Table I-3,... requirements! For more information on the Cisco Channel Partner technology specializations, and the CQS program, refer to www .cisco. com The Cisco DQOS Exam 9E0-601 The DQOS exam consists of a one-hour exam administered at a proctored exam facility affiliated either with VUE (www.vue.com) or Prometric (www.2test.com) The exam typically includes approximately 70 questions Cisco lists the topics covered in the... First, you should look to www .cisco. com occasionally during the weeks in which you are studying for the DQOS exam, just to make sure nothing new has been announced about the exam Also, you should look to www.ciscopress.com/1587200589, which is where we will post any new hints about changes to the exam As you might imagine, www .cisco. com will show any announcements a little before Cisco Press will Why Should... Required Systems Engineer Cisco Certified Design Associate (CCDA)a Cisco Product Solutions Essentials IPT Exam v2.0 (SE0-286) Enterprise Voice over Data Design Exam (9E0-411 EVODD) Deploying Quality of Service in Enterprise Networks Exam (9E0-601 DQOS) IP Telephony Solutions Exam (SE0-261) Field Engineer 1 Cisco Certified Network Professional (CCNP)* Telephony Fundamentals Exam (SE0-263) Cisco Voice Over Frame . Self-Study Cisco DQOS Exam Certification Guide Wendell Odom and Michael J. Cavanaugh Copyright © 2004 Cisco Systems, Inc. Cisco Press logo is a trademark of Cisco Systems, Inc. Published by: Cisco. cooperation with the Cisco Internet Learning Solutions Group. Cisco Press books are the only self-study books autho- rized by Cisco for CCIP and IP Telephony exam preparation. Cisco and Cisco Press present. Fundamentals Exam (SE0-263) Cisco Voice Over Frame Relay, ATM, and IP Exam (9E0-431 CVOICE) Cisco IP Telephony Exam (9E0-402 CIPT) Deploying Quality of Service in Enterprise Networks Exam (9E0-601