CWNA: Certified Wireless Network Administrator Official Study Guide (Exam PW0-100)

674 Pages·2008·12.828 MB·English

by  Barrett, Joel;Carpenter, Tom

C W NA
®
Certifi ed Wireless Network Administrator
Offi cial Study Guide
(EXAM PW0-100)
FOURTH EDITION
Tom Carpenter
Joel Barrett
Series Editor
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I dedicate this book to my God, Jesus Christ, without whom I could not have written a single
word, and to my amazing wife, Tracy, and my children, Faith, Rachel, Thomas, and Sarah,
who tolerated my odd hours and lack of attention during the writing of this book. Tracy, you
are the most amazing and wonderful thing that has ever happened to me and this book exists
because of your faith in me—you have my eternal gratitude.
Acknowledgments
I would like to acknowledge the helpful staff at McGraw-Hill for bearing
with my delays on this project. Writing two books at the same time is quite
a challenge, but we did it together. I want to thank Criss Hyde particularly.
His technical knowledge of the IEEE 802.11 standard (among other
standards) is amazing, and he is an exceptional technical editor. I also want
to thank Joel Barrett, the series editor for this book, who helped to keep me
sane during the rough stages. Thanks everyone. The book turned out very
well, and it could not have happened without you all.
About the Author
Tom Carpenter is a technical experts’ expert. He teaches in-depth
courses on Microsoft technologies, wireless networking, and security,
and professional development skills such as project management, team
leadership, and communication skills for technology professionals.
Tom holds a CWNA, CSWP, and Wireless# certification with the
CWNP program and is also a Microsoft Certified Partner. The Wireless
Networking, Windows Administration, and IT Project Management
Bootcamps that Tom offers annually provide the in-depth knowledge
IT professionals need to succeed. He lives with his lovely wife, Tracy,
and their four children, Faith, Rachel, Thomas, and Sarah, in Ohio.
His company, SYSEDCO, provides training and consulting services
throughout the United States. For more information about Tom and the
services offered by his company, visit www.SYSEDCO.com.
About the Series Editor
Joel Barrett is a senior-level wireless networking expert with Cisco
Systems. Joel has attained networking certifications such as Cisco’s CCNP
and CCDP, Microsoft’s MCSE, and Novell’s Master CNE. For wireless
certifications, he holds Cisco’s Wireless Design and Support specializations,
as well as the CWNP Program’s Wireless#, CWNA, CWSP, CWAP, and
CWNE certifications. He is CWNE #6 and a founding member of the
CWNE Roundtable, a steering committee for the CWNE certification
program. Joel is also certified to instruct Cisco’s Unified Wireless and Mesh
Networking courses.
Within Cisco, Joel consults primarily with large enterprise customers
concerning wireless deployments. He is a senior advisor for Cisco’s wireless
virtual team. He is also an author and technical editor for books such as CWNP
Dictionary of Terms and Acronyms, CWNP Wireless# Exam Mega Guide,
Wireless Networks First-Step, CWSP Official Study Guide, First Edition, and
Managing and Securing a Cisco Structured Wireless-Aware Network. He is the
series editor for McGraw-Hill’s CWNP Official Study Guides.
Joel and his wife, Barbara Kurth, live with their three children, Ashley,
Shane, and Paige, in the Atlanta, Georgia, metro area. Joel has two tenets he
lives by:
■ “Do what you love, the money will come.”
■ “If it were easy, anyone could do it.”
About the Technical Editor
Criss Hyde has thirty years of IT experience beginning with punch cards
and Fortran. He holds engineering and law degrees from Pennsylvania
State University and George Mason University respectively, and current
certifications from Apple, Cisco Systems, The CWNP Program, (ISC)2,
Sun Microsystems, and WildPackets. He became an early friend to The
CWNP Program, has edited many of its books and exams, and has earned
all of its certifications. He has worked 16 years for Raytheon Company
and is a member of the IEEE Standards Association and the Virginia
Bar Association. Criss is the husband of one wife and the father of eight
home-schooled children. He heartily agrees with Vint Cerf that for the
good of mankind and the IPv6 Internet, the NAT boxes have to go away.
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Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
Part I Understanding Wireless Technologies . . . . . . . . . . . . 1
Chapter 1 Wireless Standards, Organizations,
and Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Roles Organizations Play Within the WLAN Industry . . . . . . . . . . . . . . 5
Regulatory Domain Governing Bodies . . . . . . . . . . . . . . . . . . . . . . . . 6
ITU-R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
IEEE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
IETF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Wi-Fi Alliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Spread Spectrum Technology Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Wireless LANs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Wireless PANs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Wireless MANs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Wireless WANs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Wireless LAN Technology Roles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Corporate Data Access and End-User Mobility . . . . . . . . . . . . . . . . . 21
Network Extension to Remote Areas . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Building-to-Building Connectivity: Bridging . . . . . . . . . . . . . . . . . . . 24
Last-Mile Data Delivery: Wireless ISP . . . . . . . . . . . . . . . . . . . . . . . . 25
Small Office/Home Office (SOHO) Use . . . . . . . . . . . . . . . . . . . . . . . 26
Mobile Office Networking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Educational/Classroom Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Industrial: Warehousing and Manufacturing . . . . . . . . . . . . . . . . . . . . 28
Health Care: Hospitals and Offices . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Hotspots: Public Network Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Key Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Chapter 2 Radio Frequency and Antenna Fundamentals . . . . . . . . . . 35
Electromagnetic Waves: A Quick Tour . . . . . . . . . . . . . . . . . . . . . . . . . . 37
History of Electromagnetic Waves . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Early Radio Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Fundamentals of Electromagnetic Waves . . . . . . . . . . . . . . . . . . . . . . 39
RF Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Wavelength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Amplitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
vii
viii CWNA Certifi ed Wireless Network Administrator Offi cial Study Guide
Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
RF Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Reflection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Refraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Diffraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Scattering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Absorption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
VSWR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Return Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Amplification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Attenuation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Wave Propagation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Free Space Path Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Multipath and Delay Spread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Basic RF Math . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Watt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Milliwatt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Decibel (dB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
dBm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
dBi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
dBd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
SNR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
RSSI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Link Budget and System Operating Margin (SOM) . . . . . . . . . . . . . . 77
Fade Margin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Intentional Radiator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Equivalent Isotropically Radiated Power (EIRP) . . . . . . . . . . . . . . . . 81
FCC Rules for Output Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
RF Signal and Antenna Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Visual LOS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
RF LOS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
The Fresnel Zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Beamwidths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
Azimuth and Elevation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Isotropic Radiator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Polarization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Antenna Diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Antennas and Antenna Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Omnidirectional/Dipole Antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Semidirectional Antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Highly Directional Antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Sectorized and Phased-Array Antennas . . . . . . . . . . . . . . . . . . . . . . . . 102
Multiple-Input, Multiple-Output (MIMO)
Antenna Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Key Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107