Sixth Edition
Copyright © 2021 by John Wiley & Sons, Inc., Indianapolis, Indiana
Published simultaneously in Canada and the United Kingdom
ISBN: 978-1-119-73450-5
ISBN: 978-1-119-73633-2 (ebk.)
ISBN: 978-1-119-73453-6 (ebk.)
No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permitted under Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 646-8600. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, (201) 748-6011, fax (201) 748-6008, or online at www.wiley.com/go/permissions.
Limit of Liability/Disclaimer of Warranty: The publisher and the author make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation warranties of fitness for a particular purpose. No warranty may be created or extended by sales or promotional materials. The advice and strategies contained herein may not be suitable for every situation. This work is sold with the understanding that the publisher is not engaged in rendering legal, accounting, or other professional services. If professional assistance is required, the services of a competent professional person should be sought. Neither the publisher nor the author shall be liable for damages arising herefrom. The fact that an organization or Web site is referred to in this work as a citation and/or a potential source of further information does not mean that the author or the publisher endorses the information the organization or Web site may provide or recommendations it may make. Further, readers should be aware that Internet Web sites listed in this work may have changed or disappeared between when this work was written and when it is read.
For general information on our other products and services or to obtain technical support, please contact our Customer Care Department within the U.S. at (877) 762-2974, outside the U.S. at (317) 572-3993 or fax (317) 572-4002.
Wiley publishes in a variety of print and electronic formats and by print-on-demand. Some material included with standard print versions of this book may not be included in e-books or in print-on-demand. If this book refers to media such as a CD or DVD that is not included in the version you purchased, you may download this material at booksupport.wiley.com. For more information about Wiley products, visit www.wiley.com.
Library of Congress Control Number: 2020951883
TRADEMARKS: Wiley, the Wiley logo, and the Sybex logo are trademarks or registered trademarks of John Wiley & Sons, Inc. and/or its affiliates, in the United States and other countries, and may not be used without written permission. CWNA is a registered trademark of CWNP, LLC. All other trademarks are the property of their respective owners. John Wiley & Sons, Inc. is not associated with any product or vendor mentioned in this book.
Almost 17 years ago, we were approached by our publisher to co-author a study guide for the Certified Wireless Network Administrator (CWNA) certification exam. At the time, the phrase “Wi-Fi” was only a few years old and had yet to become ingrained in our culture. 802.11g technology had begun to emerge, and we were so excited by the blazing speeds of 54 Mbps available on the 2.4 GHz frequency band. We agreed to author the book. Six editions later, 802.11 WLAN technology has drastically evolved and Wi-Fi is now an integral part of our day-to-day lives.
The CWNA certification has long been recognized as the foundation-level certification for network professionals looking to validate their knowledge of 802.11 WLAN technology. As authors, we have been humbled by the tens of thousands of individuals who have purchased the CWNA Study Guide to assist in their pursuit of the CWNA certification. We are also humbled that many universities and colleges have selected the book as part of their curriculum for wireless technology classes. In our travels, we have met and become friends with many of our readers of the past five editions of the book. We discovered that a large number of people who purchase the book use it as a reference guide in the workplace and not just as a study guide. We have also had many people tell us that the book has helped them advance in their Wi-Fi careers. Once again, we are very humbled, and we would like to dedicate the 6th edition of the CWNA Study Guide to our readers.
Our goal has always been to educate as many people as possible about WLAN technology. If you are a newcomer to 802.11 wireless networking, we hope this book will be your first investment in Wi-Fi knowledge. If you are a veteran WLAN professional, we hope that when you are done reading this book, you will pass it along to a friend or a colleague. Sharing the Wi-Fi knowledge will be a sound investment.
Sincerely,
David Coleman and David Westcott
When we wrote the first edition of the CWNA Study Guide, David Coleman's children, Brantley and Carolina, were young children. Carolina now holds a master's degree in public policy from the University of Southern California (USC). Brantley graduated from Boston University and recently earned his Ph.D. in biochemistry at the University of Washington. David would like to thank his now adult children for years of support and for making their dad very proud. David would also like to thank his mother, Marjorie Barnes, stepfather, William Barnes, and brother, Rob Coleman, for many years of support and encouragement. David would especially like to thank his wife, Valla Ann, for bringing joy and laughter into his life every day.
David Coleman would also like to thank his friends and family at Extreme Networks (www.extremenetworks.com) and the former Aerohive Networks. There are many past and present Aerohive and Extreme employees he would like to thank, but there simply is not enough room. So thank you to all of his co-workers. It has been one wild ride the past 11 years!
David Westcott would like to thank his wife, Janie, for her love and support, and for being the cornerstone of his family. Her love and daily support of four generations of family does not go unnoticed or unappreciated.
David Westcott also would like to thank the training department at Aruba Networks. In 2004 Aruba Networks hired him as their first contract trainer. Much has changed over the years, but it is still a fun and exciting journey.
Writing CWNA: Certified Wireless Network Administrator Study Guide has once again been an adventure. We would like to thank the following individuals for their support and contributions during the entire process.
We must first thank Sybex acquisitions editor Jim Minatel for reaching out to us and encouraging us to write this sixth edition of our book. We would also like to thank our development editor, Kim Wimpsett, who has been a pleasure to work with on multiple book projects. We also need to send special thanks to our editorial manager, Pete Gaughan; our content refinement specialist, Barath Kumar Rajasekaran; Elizabeth Welch, our copyeditor; and Louise Watson, our proofreader.
We also need to give a big shout-out to our technical editor, Ben Wilson of Fortinet (www.fortinet.com). Ben has accumulated years of Wi-Fi experience working for three major WLAN vendors. The feedback and input provided by Ben was invaluable.
Special thanks must also go out to both Andrew vonNagy, CWNE #84, and Marcus Burton, CWNE #78, for their expertise as technical editors in earlier editions of the book.
Andrew Crocker has again provided us with wonderful photographs and some amazing editing of some not so wonderful photographs that we provided him. You can see much more of his work and talent at www.andrewcrocker.photography.
Thanks to Proxim and to Ken Ruppel (kenruppel@gmail.com) for allowing us to include the video Beam Patterns and Polarization of Directional Antennas with the book's online resources, which can be accessed at www.wiley.com/go/cwnasg6e.
Special thanks goes to Andras Szilagyi, for creating the EMANIM web application that is used with the exercises in Chapter 3, “Radio Frequency Fundamentals.” You can reach Andras at www.szialab.org.
Thanks to Chris DePuy of the technology research firm 650 Group (www.650group.com) for the WLAN industry trend analysis.
Thanks to Marko Tisler, CWNE #126, for his content contribution about APIs. Thanks to Gregor Vucajnk, CWNE #96, for his copy regarding LTE. Thanks to Karl Benedict for his input and content about directional antennas. Thanks to Perry Correll for his input regarding 802.11ax and Wi-Fi 6E.
Most gracious appreciation to Rick Murphy, CWNE #10, for his content regarding OFDM. Rick offers some outstanding WLAN training resources at howwirelessworks.com.
Very special thanks to Adrian Granados for all of his contributions to the wireless community. Be sure and check out his cool Wi-Fi applications at www.intuitibits.com.
We have to give a big shout-out to Lee Badman, CWNE #200, for his parody blogs and memes that he has created about past editions of this book. (He writes great technical blogs as well.)
Some other WLAN rock stars that are mentioned in the copy of this book: Sam Clements, CWNE #101; Nigel Bowden, CWNE #135; Mike Albano, CWNE #150; Eddie Forero, CWNE #160; James Garringer, CWNE #179; Glen Cate, CWNE #181; Jerome Henry, CWNE #45; François Vergès, CWNE #180; Rowell Dionicio, CWNE #210; Manon Lessard, CWNE #275; Phil Morgan, CWNE #322; Mac Deryng, CWNE #357, and Matt Starling, CWNE #369.
We would also like to thank the following individuals and companies for their support and contributions to the book:
www.divdyn.com)www.ventev.com)www.ibwave.com)www.hiveradar.com)www.acrylicwifi.com)www.wi-fi.org)www.netally.com)www.masimo.com)www.ekahau.com)www.oberoninc.com)www.metageek.com)We also want to thank Keith Parsons, CWNE #3, and his team at wirelessLAN Professionals. Keith has built a worldwide community of WLAN experts who share knowledge. You can learn more about the wirelessLAN Professionals conferences at www.wlanprofessionals.com.
We would also like to thank at Tom Carpenter, CWNE #104, of the CWNP program (www.cwnp.com). All CWNP employees, past and present, should be proud of the internationally renowned wireless certification program that sets the education standard within the enterprise Wi-Fi industry. It has been a pleasure working with all of you for the past two decades.
Finally, we would like to thank Mark Hung, Vice President, Technology and Engineering at the Wi-Fi Alliance, for the thought-provoking foreword that he wrote for this book.
David D. Coleman is the Director of Product Marketing for Extreme Networks (www.extremenetworks.com). David is a public speaker and proficient technical author who specializes in Wi-Fi and cloud technologies, and he is a member of the Extreme Networks Technical Evangelism team. David travels the world for both customer and channel partner engagements, speaking events, and training sessions. He has instructed IT professionals from around the globe in Wi-Fi design, security, administration, and troubleshooting.
David has written multiple books, blogs, and white papers about wireless networking, and he is considered an authority on 802.11 technology. Prior to working at Extreme, he specialized in corporate and government Wi-Fi training and consulting. In the past, he has provided Wi-Fi consulting for numerous private corporations, the U.S. military, and other federal and state government agencies. David is also the 2020 recipient of the Wi-Fi Lifetime Achievement Award (www.thewifiawards.com/2020-award-winners). When he is not traveling, he resides in both Atlanta, Georgia, and Lake Chapala, Mexico, with his wife, Valla Ann. David is CWNE #4, and he can be reached via email at mistermultipath@gmail.com. Please follow David on Twitter: @mistermultipath.
David A. Westcottis an independent consultant and technical trainer with more than 35 years of experience. He has been a certified trainer for more than 28 years and specializes in wireless networking, wireless management and monitoring, and network access control. He has provided training to thousands of students at government agencies, corporations, and universities in more than 30 countries around the world. David was an adjunct faculty member at Boston University's Corporate Education Center for more than 10 years. He is the author of Understanding ArubaOS: Version 8.x (Bowker, 2019) and Understanding ArubaOS: Version 6.x (Westcott Consulting, Inc., 2017), and he has co-authored multiple books, written numerous white papers, and developed many courses on wired and wireless networking technologies and networking security.
David was a member of the original CWNE Roundtable. He is CWNE #007 and has earned certifications from many companies, including Aruba Networks, Silver Peak, Cisco, Microsoft, Ekahau, EC-Council, CompTIA, and Novell. He lives in Concord, Massachusetts, with his wife, Janie. David can be reached via email at david@westcott-consulting.com. Please follow David on Twitter: @davidwestcott.
Ben Wilson has been involved with wireless since its early commercialized beginnings, working for different vendors and technologies along the way. Having worked in various roles, he has installed more APs and done more integrations than he cares to remember over the last 20 years. Today Ben works as VP of Project Management at Fortinet, where he helps drive product strategy, direction, and development for wireless and other technologies. Please follow Ben on Twitter: @AirNetworkBen.