Certified Wireless Network Administrator Official Study Guide

390 Pages·2002·6.7 MB·English

by  Planet3 Wireless Inc.

cwna Industry
TM
Approved!
Endorsed by the
Wireless LAN
Association
Certified Wireless
Network AdministratorTM
Official Study Guide
Exam PW0-100
Objective-by-Objective coverage
of the CWNA certification exam
Vendor-neutral wireless network
training and certification
Planet3 Wireless
CWNP™ Certification Program

The Certified Wireless Network Professional Training & Certification Program is
intended for individuals who administer, install, design, and support IEEE 802.11
compliant wireless networks. Because the CWNP program is vendor neutral, candidates
who achieve the different levels of CWNP Certification will be trained and qualified to
administer and support many different brands of wireless LAN hardware. Although there
are many manufacturers of wireless LAN hardware, the technologies behind the hardware
– Radio Frequency and Local Area Networking – are the same for each piece of gear.
Each manufacturer approaches these technologies in different ways.

The CWNP program consists of 4 levels of certification:

Administrator – Site survey, installation and management of 802.11 compliant wireless
LANs

Security Expert – Design and implementation of 802.11 security techniques, processes,
hardware, and software

Integrator – Advanced site survey, design, bridging and integration of 802.11 compliant
wireless LANs

Engineer – Lab intensive approach to design, implementation, troubleshooting & repair,
security and integration of 802.11 compliant wireless LANs

CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc.
Copyright © 2002 Planet3 Wireless, Inc., P.O. Box 412, Bremen Georgia 30110. World rights reserved. No part of
this publication may be stored in any retrieval system, transmitted, or reproduced in any way, including but not
limited to photocopying, photographing, magnetic, electronic, or other record, without the prior written agreement
and written permission of Planet3 Wireless, Inc.

ISBN: 0-9716057-2-6
Version: FAY534IR8E1

CNWP, CWNA, CWNI, CWSE, CWNE, CWAP, CWEC and their respective logos are registered marks of Planet3
Wireless, Inc. in the United States and/or other countries.

This study guide and reference manual are not sponsored by or affiliated with any wireless LAN manufacturer,
including those mentioned in the text and in the lab exercise notes.

TRADEMARKS: Planet3 Wireless, Inc. has attempted throughout this book to distinguish proprietary trademarks
from descriptive terms by following the capitalization style used by the manufacturers. The author and publisher
have made their best efforts to prepare this book, and the content is based upon final release software whenever
possible. Portions of the manuscript may be based on pre-release versions supplied by software manufactures. The
author and publisher make no representation or warranties of any kind with regard to the completeness or accuracy
of the contents herein and accept no liability of any kind including but not limited to performance, merchantability,
fitness for any particular purpose, or any losses or damages of any kind caused or alleged to be caused directly or
indirectly from this book.

Manufactured in the United States of America

CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc.
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CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc.
We at Planet3 Wireless would like to dedicate this book to our Lord Jesus Christ. It is through Him that
we have had the talent, time, encouragement, and strength to work many long months in preparing this
text. Our goal through the creation of this book and through all things that He allows us to do going
forward is to glorify Him. We acknowledge His hand in every part of our company, our work, and our
friendships. We would also like to thank our families who have been amazingly supportive, our friends
who have encouraged us and everyone that contributed to this book in any way.

“I can do all things through Christ, who strengthens me.” – Philippians 4:13

CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc.
Acknowledgements

(cid:131) Devin Akin
(cid:131) Kevin Sandlin
(cid:131) Scott Turner
(cid:131) Robert Nicholas
(cid:131) Josh McCord
(cid:131) Jeff Jones
(cid:131) Stan Brooks
(cid:131) Bill Waldo
(cid:131) Barry Oxford

Planet3 Wireless, Inc. would like to acknowledge and thank the following people for
their tireless contributions to this work:

Devin Akin, whose knowledge of wireless LANs, networking, and radio frequency
surprised even us. His talents to convey, teach, write, and edit were essential in making
this the most accurate and comprehensive writing on wireless LANs in today's market.

Scott Turner, who constantly keeps us in line and focused on what is important. Scott's
work in formatting, framing, content organization, and graphics creation was
indispensable. Scott's eye for detail and his motivation for perfection in everything he
does keep us in awe.

Kevin Sandlin, for his intellect to make difficult concepts sound simple, his skill to write
and edit the most difficult material, and his ability to motivate every member of the team
to do their best and to keep their eyes on the sometimes moving target. His leadership
skills are second to none.

Robert Nicholas, for his ability to conceptualize and create difficult graphics and radio
frequency concepts, his savvy in presentation of difficult material, and his ability to find
the answer to even the most vague concepts through diligent research and study. His
effort in support of this book is greatly appreciated.

Jeff Jones and Josh McCord, who have been with Planet3 since the beginning of this
project. Their willingness to volunteer as much time and effort as was needed to make all
of it possible has been amazing. They have been an inspiration to the entire team. Their
relentless pursuit of perfection in support of Planet3's mission is recognized and greatly
appreciated.

Stan Brooks, Bill Waldo, and Barry Oxford, each of whom brought a unique set of
skills to the review and quality assurance process for this publication. Their time, effort
and eye for necessary changes were immeasurable, and helped to publish this book in a
timely manner.

CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc.
vi Contents
Contents at a Glance

Introduction xvi
Chapter 1 Introduction to Wireless LANs 1
Chapter 2 Radio Frequency (RF) Fundamentals 17
Chapter 3 Spread Spectrum Technology 45
Chapter 4 Wireless LAN Infrastructure Devices 71
Chapter 5 Antennas and Accessories 103
Chapter 6 Wireless LAN Organizations and Standards 145
Chapter 7 802.11 Network Architecture 167
Chapter 8 MAC and Physical Layers 201
Chapter 9 Troubleshooting Wireless LAN Installations 223
Chapter 10 Wireless LAN Security 259
Chapter 11 Site Survey Fundamentals 295
Appendix A RF in Perspective 341
Glossary 347

CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc.
Contents vii
Contents

Introduction xxiv
Chapter 1 Introduction to Wireless LANs 1
The Wireless LAN Market 2
Today’s Wireless LAN Standards 3
Applications of Wireless LANs 3
Access Role 4
Network Extension 5
Building-to-Building Connectivity 5
Last Mile Data Delivery 6
Mobility 7
Small Office-Home Office 8
Summary 10
Key Terms 11
Review Questions 12
Answers to Review Questions 15
Chapter 2 Radio Frequency (RF) Fundamentals 17
Radio Frequency 18
RF Behaviors 19
Gain 19
Loss 19
Reflection 20
Refraction 21
Diffraction 22
Scattering 23
Voltage Standing Wave Ratio (VSWR) 23
VSWR Measurements 24
Effects of VSWR 24
Solutions to VSWR 25
Principles of Antennas 25
Line of Sight (LOS) 25
Fresnel Zone 26
Obstructions 27
Antenna Gain 27
Intentional Radiator 27
Equivalent Isotropically Radiated Power (EIRP) 28
Radio Frequency Mathematics 29
Units of Measure 30
Watts (W) 30
Milliwatt 30
Decibels 30
dBm 32
dBi 34
Accurate Measurements 35
Key Terms 37
Review Questions 38
Answers to Review Questions 43
Chapter 3 Spread Spectrum Technology 45
CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc.
viii Contents
Introducing Spread Spectrum 46
Narrow Band Transmission 46
Spread Spectrum Technology 47
Uses of Spread Spectrum 48
Wireless Local Area Networks 48
Wireless Personal Area Networks 49
Wireless Metropolitan Area Networks 49
FCC Specifications 49
Frequency Hopping Spread Spectrum (FHSS) 50
How FHSS Works 50
Effects of Narrow Band Interference 51
Frequency Hopping Systems 51
Channels 51
Dwell Time 52
Hop Time 53
Dwell Time Limits 53
FCC Rules affecting FHSS 54
Direct Sequence Spread Spectrum (DSSS) 55
How DSSS Works 55
Direct Sequence Systems 55
Channels 56
Effects of Narrow Band Interference 58
FCC Rules affecting DSSS 58
Comparing FHSS and DSSS 58
Narrowband Interference 58
Cost 59
Co-location 59
Equipment compatibility and availability 60
Data rate & throughput 60
Security 61
Standards Support 61
Key Terms 62
Review Questions 63
Answers to Review Questions 68
Chapter 4 Wireless LAN Infrastructure Devices 71
Access Points 72
Access Point Modes 73
Root Mode 74
Bridge Mode 74
Repeater Mode 75
Common Options 76
Fixed or Detachable Antennas 76
Advanced Filtering Capabilities 76
Removable (Modular) Radio Cards 77
Variable Output Power 77
Varied Types of Wired Connectivity 77
Configuration and Management 78
Wireless Bridges 79
Wireless Bridge Modes 80
Root Mode 80
Non-root Mode 81
CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc.
Contents ix
Access Point Mode 81
Repeater Mode 81
Common Options 82
Fixed or Detachable Antennas 82
Advanced Filtering Capabilities 83
Removable (Modular) Radio Cards 83
Variable Output Power 83
Varied Types of Wired Connectivity 83
Configuration and Management 84
Wireless Workgroup Bridges 84
Common Options 85
Configuration and Management 85
Wireless LAN Client Devices 86
PCMCIA & Compact Flash Cards 86
Wireless Ethernet & Serial Converters 87
USB Adapters 88
PCI & ISA Adapters 88
Configuration and Management 89
Driver Installation 89
Manufacturer Utilities 89
Wireless Residential Gateways 90
Common Options 91
Configuration and Management 92
Enterprise Wireless Gateways 92
Configuration and Management 94
Key Terms 95
Review Questions 96
Answers to Review Questions 100
Chapter 5 Antennas and Accessories 103
RF Antennas 105
Omni-directional (Dipole) Antennas 105
Usage 107
Semi-directional Antennas 108
Usage 109
Highly-directional Antennas 110
Usage 110
RF Antenna Concepts 111
Polarization 111
Gain 113
Beamwidth 113
Free Space Path Loss 114
The 6dB Rule 115
Antenna Installation 115
Placement 115
Mounting 116
Appropriate Use 116
Orientation 116
Alignment 117
Safety 117
Maintenance 118
Power over Ethernet (PoE) Devices 118
CWNA Study Guide © Copyright 2002 Planet3 Wireless, Inc.