Table Of ContentSECOND EDITION
802.11® Wireless Networks: The
Definitive Guide
Matthew Gast
Beijing • Cambridge • Farnham • Köln • Sebastopol • Tokyo
802.11® Wireless Networks: The Definitive Guide, Second Edition
by Matthew Gast
Copyright © 2005 Mathhew Gast. All rights reserved.
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2008-10-20 Sixth release
2010-04-12 Seventh release
2010-08-30 Eighth release
2011-02-18 Ninth release
2013-04-05 Tenth release
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ISBN: 978-0-596-10052-0
[LSI]
1365099566
Table of Contents
Foreword ................................................................... ix
Preface ..................................................................... xi
1. Introduction to Wireless Networking ....................................... 1
Why Wireless? 1
What Makes Wireless Networks Different 6
A Network by Any Other Name... 8
2. Overview of 802.11 Networks ............................................ 13
IEEE 802 Network Technology Family Tree 14
802.11 Nomenclature and Design 15
802.11 Network Operations 24
Mobility Support 30
3. 802.11 MAC Fundamentals .............................................. 33
Challenges for the MAC 35
MAC Access Modes and Timing 38
Contention-Based Access Using the DCF 42
Fragmentation and Reassembly 45
Frame Format 47
Encapsulation of Higher-Layer Protocols Within 802.11 55
Contention-Based Data Service 56
Frame Processing and Bridging 65
4. 802.11 Framing in Detail ................................................ 69
Data Frames 69
Control Frames 78
Management Frames 84
Frame Transmission and Association and Authentication States 114
iii
5. Wired Equivalent Privacy (WEP) ......................................... 117
Cryptographic Background to WEP 118
WEP Cryptographic Operations 120
Problems with WEP 126
Dynamic WEP 130
6. User Authentication with 802.1X ........................................ 133
The Extensible Authentication Protocol 134
EAP Methods 140
802.1X: Network Port Authentication 145
802.1X on Wireless LANs 149
7. 802.11i: Robust Security Networks, TKIP, and CCMP ........................ 153
The Temporal Key Integrity Protocol (TKIP) 153
Counter Mode with CBC-MAC (CCMP) 164
Robust Security Network (RSN) Operations 168
8. Management Operations ............................................... 175
Management Architecture 175
Scanning 176
Authentication 181
Preauthentication 185
Association 189
Power Conservation 193
Timer Synchronization 202
Spectrum Management 204
9. Contention-Free Service with the PCF .................................... 219
Contention-Free Access Using the PCF 219
Detailed PCF Framing 223
Power Management and the PCF 228
10. Physical Layer Overview ............................................... 231
Physical-Layer Architecture 231
The Radio Link 231
RF Propagation with 802.11 238
RF Engineering for 802.11 244
11. The Frequency-Hopping (FH) PHY ........................................ 247
Frequency-Hopping Transmission 247
Gaussian Frequency Shift Keying (GFSK) 252
FH PHY Convergence Procedure (PLCP) 254
iv | Table of Contents
Frequency-Hopping PMD Sublayer 257
Characteristics of the FH PHY 258
12. The Direct Sequence PHYs: DSSS and HR/DSSS (802.11b) ..................... 259
Direct Sequence Transmission 259
Differential Phase Shift Keying (DPSK) 266
The “Original” Direct Sequence PHY 269
Complementary Code Keying 273
High Rate Direct Sequence PHY 274
13. 802.11a and 802.11j: 5-GHz OFDM PHY ................................... 283
Orthogonal Frequency Division Multiplexing (OFDM) 284
OFDM as Applied by 802.11a 289
OFDM PLCP 298
OFDM PMD 300
Characteristics of the OFDM PHY 304
14. 802.11g: The Extended-Rate PHY (ERP) ................................... 307
802.11g Components 307
ERP Physical Layer Convergence (PLCP) 312
ERP Physical Medium Dependent (PMD) Layer 316
15. A Peek Ahead at 802.11n: MIMO-OFDM ................................... 321
Common Features 322
WWiSE 324
TGnSync 335
Comparison and Conclusions 350
16. 802.11 Hardware ..................................................... 353
General Structure of an 802.11 Interface 353
Implementation-Specific Behavior 358
Reading the Specification Sheet 360
17. Using 802.11 on Windows .............................................. 363
Windows XP 363
Windows 2000 377
Windows Computer Authentication 379
18. 802.11 on the Macintosh ............................................... 383
The AirPort Extreme Card 383
802.1X on the AirPort 388
Table of Contents | v
19. Using 802.11 on Linux ................................................. 397
PCMCIA Support on Linux 397
Linux Wireless Extensions and Tools 406
Agere (Lucent) Orinoco 412
Atheros-Based cards and MADwifi 415
802.1X on Linux with xsupplicant 418
20. Using 802.11 Access Points ............................................. 425
General Functions of an Access Point 426
Power over Ethernet (PoE) 432
Selecting Access Points 434
Cisco 1200 Access Point 438
Apple AirPort 443
21. Logical Wireless Network Architecture ................................... 449
Evaluating a Logical Architecture 449
Topology Examples 463
Choosing Your Logical Architecture 485
22. Security Architecture .................................................. 489
Security Definition and Analysis 490
Authentication and Access Control 495
Ensuring Secrecy Through Encryption 504
Selecting Security Protocols 512
Rogue Access Points 523
23. Site Planning and Project Management .................................. 531
Project Planning and Requirements 532
Network Requirements 534
Physical Layer Selection and Design 545
Planning Access-Point Placement 550
Using Antennas to Tailor Coverage 558
24. 802.11 Network Analysis ............................................... 567
Network Analyzers 567
Ethereal 570
802.11 Network Analysis Checklist 579
Other Tools 584
25. 802.11 Performance Tuning ............................................ 587
802.11 Performance Calculations 587
Improving Performance 590
vi | Table of Contents
Tunable 802.11 Parameters 592
26. Conclusions and Predictions ............................................ 599
Standards Work 599
Current Trends in Wireless Networking 601
The End 611
Glossary ................................................................... 613
Index ..................................................................... 623
Table of Contents | vii
