Published by Cisco Press (April 29, 2015) © 2015
Jim Geier
Designing and Deploying 802.11 Wireless Networks
Second Edition
A Practical Guide to Implementing 802.11n and 802.11ac Wireless Networks For Enterprise-Based Applications
Plan, deploy, and operate high-performance 802.11ac and 802.11n wireless networks
The new 802.11ac standard enables WLANs to deliver significantly higher performance. Network equipment manufacturers have refocused on 802.11ac- and 802.11n-compliant solutions, rapidly moving older versions of 802.11 toward “legacy” status. Now, there’s a complete guide to planning, designing, installing, testing, and supporting 802.11ac and 802.11n wireless networks in any environment, for virtually any application.
Jim Geier offers practical methods, tips, and recommendations that draw on his decades of experience deploying wireless solutions and shaping wireless standards. He carefully introduces 802.11ac’s fundamentally different design, site survey, implementation, and network configuration techniques, helping you maximize performance and avoid pitfalls.
Geier organizes each phase of WLAN deployment into clearly defined steps, making the entire planning and deployment process easy to understand and execute. He illuminates key concepts and methods through realistic case studies based on current Cisco products, while offering tips and techniques you can use with any vendor’s equipment. To build your skills with key tasks, you’ll find several hands-on exercises relying on free or inexpensive tools.
Whether you’re deploying an entirely new wireless network or migrating from older equipment, this guide contains all the expert knowledge you’ll need to succeed.
Jim Geier has 30 years of experience planning, designing, analyzing and implementing communications, wireless, and mobile systems. Geier is founder and Principal Consultant of Wireless-Nets, Ltd., providing wireless analysis and design services to product manufacturers. He is also president, CEO, and co-founder of Health Grade Networks, providing wireless network solutions to hospitals, airports, and manufacturing facilities. His books include the first edition of Designing and Deploying 802.11n Wireless Networks (Cisco Press); as well as Implementing 802.1X Security Solutions and Wireless Networking Handbook. Geier has been active in the IEEE 802.11 Working Group and Wi-Fi Alliance; has chaired the IEEE Computer Society (Dayton Section) and various conferences; and served as expert witness in patent litigation related to wireless and cellular technologies.
- Review key 802.11 concepts, applications, markets, and technologies
- Compare ad hoc, mesh, and infrastructure WLANs and their components
- Consider the impact of radio signal interference, security vulnerabilities, multipath propagation, roaming, and battery limitations
- Thoroughly understand today’s 802.11 standards in the context of actual network deployment and support
- Plan your deployment: scoping, staffing, schedules, budgets, risks, feasibility analysis, and requirements
- Architect access networks and distribut
Introduction xxv
Part I: Fundamental Concepts
Chapter 1 Introduction to Wireless LANs 1
Wireless LAN Markets and Applications 1
Retail 2
Warehousing 2
Healthcare 4
Hospitality 5
Voice over WLAN 5
Video Surveillance 6
Home and Small Office 7
General Enterprise Systems 8
Location-Aware Wireless Applications 8
Benefits of Wireless Networks 10
Mobility 10
Installation in Difficult-to-Wire Areas 11
Increased Reliability 11
Reduced Installation Time 12
Long-Term Cost Savings 12
Productivity Gain Is the Answer 12
Wireless LAN Technologies 14
Initial 802.11 16
802.11a 16
802.11b 16
802.11g 17
Current Standards: 802.11n and 802.11ac 18
Comparison of 802.11 Standards 19
Wi-Fi Certification 19
Wireless LANs: A Historical Perspective 21
The Early Days 21
Initial 802.11 Standardization 22
802.11n and 802.11ac Standardization 23
Summary 25
Chapter 2 Radio Wave Fundamentals 27
Radio Wave Attributes 27
Amplitude 28
Frequency 28
Phase 29
RF System Components 29
RF Transceiver 29
RF Modulation 30
Amplitude-Shift Keying 31
Frequency-Shift Keying 32
Phase-Shift Keying 33
Quadrature Amplitude Modulation 33
Spread Spectrum 33
Orthogonal Frequency-Division Multiplexing 36
RF Signal Propagation 36
Attenuation 37
Free Space Loss 37
Physical Obstacles 38
Multipath Propagation 39
Noise and Signal-to-Noise Ratio 39
RF Mathematics 41
Converting Units 41
Summary 42
Chapter 3 Wireless LAN Types and Components 43
Types of Wireless LANs 43
Ad Hoc Wireless LANs 43
Infrastructure Wireless LANs 45
Wireless Mesh Networks 48
Wireless LAN Components 50
Client Devices 50
Client Radio 51
Industry Standard Architecture 53
Peripheral Component Interconnect 54
Mini-PCI 54
PC Card 54
ExpressCard 55
CompactFlash 55
Universal Serial Bus 55
Access Points 56
Autonomous Access Points 56
Controller-Based Access Points 57
Wi-Fi Routers 58
Mesh Nodes 60
Antennas 60
RF Amplifiers 62
Repeaters 63
Bridges 64
Network Infrastructure Components 65
Network Distribution Systems 65
Switches 65
Optical Fiber 67
Power over Ethernet 67
Application Connectivity Software 70
Terminal Emulation 70
Browser-Based Approaches 71
Direct Database Interfaces 72
Wireless Middleware 72
Summary 74
Chapter 4 Wireless LAN Implications 75
Security Vulnerabilities 75
Passive Monitoring 76
Unauthorized Access 79
Unauthorized Access Leads to Compromise of Financial Data 82
Denial-of-Service Attacks 83
Radio Signal Interference 85
Microwave Oven Interference 86
Cordless Phone Interference 88
Bluetooth Interference 90
Neighboring Wireless LAN Interference 92
Impacts of Multipath Propagation 95
Roaming Issues 96
Battery Limitations 97
Interoperability Problems 98
Installation Issues 98
Summary 99
Part II: The 802.11 Standard
Chapter 5 Introduction to IEEE 802.11 and Related Standards 101
The Importance of Standards 101
Types of Standards 102
Institute of Electrical and Electronics Engineers 103
Benefits of the 802.11 Standard 104
Appliance Interoperability 104
Fast Product Development 105
Stable Future Migration 105
Price Reductions 106
Avoiding Silos 106
The IEEE 802 LAN Standards Family 107
802.11 MAC Sublayer 109
802.11 Physical Layer 110
IEEE 802.2 110
Unacknowledged Connectionless Service 111
Connection-Oriented Service 112
Continuous ARQ 113
Stop-and-Wait ARQ 114
Acknowledged Connectionless Service 115
IEEE 802.11 Features 116
Station Services 117
Authentication 117
Deauthentication 118
Privacy 118
Distribution System Services 118
Association 118
Disassociation 118
Distribution 118
Integration 119
Re-association 119
Station States and Corresponding Frame Types 119
Summary 121
Chapter 6 IEEE 802.11 Medium Access Control (MAC) Layer 123
Primary 802.11 MAC Layer Functions 123
Data Delivery 124
Medium Access 125
Distributed Coordination Function 126
Hybrid Coordination Function 127
Error Recovery 129
Data Frame Acknowledgements 129
Dynamic Rate Switching 130
Data Frame Aggregation 131
MSDU Aggregation 132
MPDU Aggregation 132
Data Frame Fragmentation 132
Encryption 134
Wired Equivalent Privacy 134
Temporal Key Integrity Protocol 135
CCMP 136
Multicasting 136
Connectivity 138
Scanning for Networks 138
Authentication 140
Open System Authentication 140
Shared Key Authentication 141
IEEE 802.1X Port-Based Authentication 142
Associating with the Access Point 143
4-Way Handshake 145
Timing and Synchronization 145
Short IFS 146
PCF IFS 146
DCF IFS 147
Extended IFS 147
RTS/CTS 147
Power Management 149
802.11 MAC Frame Structures 150
Protocol Version Field 150
Type Field 150
Subtype Field 151
To DS Field 152
From DS Field 152
More Frag Field 152
Retry Field 153
Power Management Field 153
More Data Field 153
Protected Frame Field 153
Order Field 153
Duration/ID Field 153
Address 1, 2, 3, and 4 Fields 154
Sequence Control Field 154
QoS Control Field 155
HT Control Field 155
Frame Body Field 155
Frame Check Sequence Field 155
MAC Frame Types 156
Management Frames 156
Association Request Frame 156
Association Response Frame 156
Re-association Request Frame 157
Re-association Response Frame 157
Probe Request Frame 157
Probe Response Frame 157
Beacon Frame 157
ATIM Frame 159
Disassociation Frame 159
Authentication Frame 159
Deauthentication Frame 160
Action Frame 160
Action No ACK Frame 160
Management Frame Body Contents 160
Control Frames 162
Control Wrapper Frame 162
Block ACK Request Frame 162
Block ACK Frame 162
Power-Save Poll Frame 162
Request-to-Send Frame 162
Clear-to-Send Frame 162
Acknowledgement Frame 163
Contention-Free End Frame 163
CF End + CF ACK Frame 163
Data Frames 163
Interoperability 164
Summary 165
Chapter 7 IEEE 802.11 Physical (PHY) Layers 167
802.11 Physical Layer Architecture 167
PLCP Sublayer 168
PMD Sublayer 168
802.11 Physical Layer Functions 169
Carrier Sense Function 169
Transmit Function 169
Receive Function 170
Legacy 802.11 Physical Layers 170
Frequency-Hopping Spread Spectrum PHY 170
Direct-Sequence Spread Spectrum PHY 172
Infrared PHY 175
Orthogonal Frequency-Division Multiplexing PHY (802.11a) 175
High-Rate Direct-Sequence Spread Spectrum PHY (802.11b) 178
Extended-Rate PHY (802.11g) 180
High-Throughput (802.11n) 180
MIMO Concepts 180
Transmit Beamforming 180
Spatial Multiplexing 181
Channel Bonding 183
802.11n Modulation 184
Interoperability 188
Very High-Throughput 6 GHz (802.11ac) 188
RF Channel Bandwidth 188
Multi-User MIMO 189
Interoperability 189
Summary 190
Part III: Wireless Network Design
Chapter 8 Planning a Wireless LAN Deployment 191
Project Management Principles 191
Wireless LAN Deployment Planning Steps 193
Step 1: Defining the Project Scope 194
Project Charter 194
Assumptions 194
Constraints 194
Step 2: Developing the Work Breakdown Structure 196
Requirements Definition Phase 196
Design Phase 197
Implementation Phase 199
Operations and Maintenance Phase 201
Step 3: Identifying Staffing 204
Step 4: Creating a Schedule 206
Step 5: Developing a Budget 207
Preliminary Requirements and Design 207
Hardware and Software Costs 208
Deployment Services Costs 211
Ongoing Operations and Maintenance Costs 212
Step 6: Evaluating Risks 215
Step 7: Analyzing Feasibility 217
Costs 217
Benefits 218
Impacts on Users 218
Impacts on Existing Systems 219
Making the Decision to Proceed 219
Executing the Project 221
The Kickoff Meeting 222
Evaluating the Outcome of the Project 223
Summary 225
Chapter 9 Defining Requirements for a Wireless LAN 227
Requirements Attributes 227
Requirements Definition Steps 228
Step 1: Gathering Information 229
Interviewing Users 229
Interviewing IT Staff 230
Reviewing the Existing Infrastructure and Systems 230
Step 2: Analyzing Requirements 231
Application Requirements 231
Client Device Requirements 233
Signal Coverage Requirements 234
Utilization Requirements 236
Mobility Requirements 238
Security Requirements 240
Scalability Requirements 243
Existing Network Infrastructure Requirements 244
Environmental Requirements 245
Aesthetic Requirements 248
Step 3: Documenting Requirements 248
Step 4: Obtaining Requirements Approval 249
Summary 250
Chapter 10 System Architecture Considerations 251
Architectural Considerations 251
Wireless Access Networks 252
Autonomous Access Point Architecture 253
Controller-Based Access Point Architecture 254
Mesh Network Architecture 256
Ad Hoc Architecture 258
2.4-GHz Versus 5-GHz 259
Geographic Location Considerations 260
Performance Considerations 260
Existing Client Device Considerations 260
Facility Size Considerations 260
Radio Signal Interference Considerations 261
Hybrid Frequency Band Considerations 261
Common Infrastructure Considerations 262
Migration Considerations 264
Redundancy Considerations 264
Controller Redundancy 264
Access Point Redundancy 267
Distribution Systems 269
Switch Considerations 269
PoE Considerations 269
Voice over WLAN Systems 271
Single-Site Architecture 271
Multisite WAN with Centralized Call Processing 272
Multisite WAN with Distributed Call Processing 274
Application Connectivity 277
Terminal Emulation Considerations 277
Browser-Based Connectivity Considerations 279
Direct Database Considerations 280
Wireless Middleware Considerations 282
Summary 285
Chapter 11 Range, Performance, and Roaming Considerations 287
Range Versus Performance 287
Range Considerations 288
Signal Coverage Requirements 288
Radio Frequency Bands 289
Transmit Power Settings 290
Transmission Channel Settings 291
Data Rate Settings 292
Antennas 294
Amplifiers 295
Repeaters 296
Physical Obstacles 297
Radio Signal Interference 297
Performance Considerations 299
Throughput Versus Data Rate 299
Radio Frequency Bands 300
Transmit Power Settings 300
Transmission Channel Settings 301
Data Rate Settings 302
Antennas 302
Amplifiers 303
Radio Signal Interference 304
Channel Width Settings 304
Signal Coverage 305
Fragmentation Settings 305
RTS/CTS Settings 306
Bandwidth Control Mechanisms 306
Microcell Deployment Strategies 307
Roaming Considerations 309
Roaming Levels 309
Access Point Roaming 310
Subnet Roaming 310
Wireless ISP Roaming 312
Wireless IP Phone Roaming 312
Mobility Settings 313
Summary 313
Chapter 12 Radio Frequency Considerations 315
Frequency Band Selection 315
2.4-GHz Frequency Band 315
5-GHz Frequency Band 316
Transmission Channel Settings 316
Manual Channel Settings 316
Single-Level Facilities 317
Multilevel Facilities 319
Adaptive Channel Settings 321
Difficult-to-Cover Areas 321
Signal Coverage in Elevators 322
Signal Coverage in Stairwells 324
Signal Coverage in Parking Areas 324
Radio Signal Interference Reduction 325
Summary 326
Chapter 13 Security Considerations 327
Security Elements 327
Encryption 328
Authentication 330
EAP Methods 331
Authentication Servers 332
Guest Access 333
Rogue Access Point Detection 334
RF Shielding 335
Wireless Security Policies 337
Summary 339
Part IV: Wireless Network Installation and Testing
Chapter 14 Test Tools 341
Tool Considerations 341
Spectrum Analyzers 342
Real-Time Fast Fourier Transform 342
FFT Duty Cycle 344
Swept Spectrogram 345
Active Devices 345
Recording Spectrum Data 346
Signal Coverage Testers 346
Heat Maps 346
Positioning 347
Passive Versus Active Modes 349
Simulation 349
Free Signal Coverage Tester: NetStumbler 349
Wireless Protocol Analyzers 350
Filtering Frames 351
Recording Traces 352
Free Protocol Analyzer: WireShark 352
Summary 354
Chapter 15 Performing a Wireless Site Survey 355
Wireless Site Survey Considerations 356
Reviewing Requirements 357
Selecting Site Survey Tools 358
Obtaining Floor Diagrams 359
Inspecting the Facility 360
Assessing the Existing Network Infrastructure 360
Communications Rooms 360
Switches and Power over Ethernet 361
WAN 361
Identifying Potential Radio Signal Interference 361
Defining Signal Values for Acceptable Signal Coverage 364
Minimum Received Signal Strength 364
Minimum SNR 364
Uplink Versus Downlink Signal Values 365
Identifying Optimum Access Point Antenna Installation Locations 367
Propagation Testing 367
Test Access Point Configuration 367
Antenna Considerations 368
Identifying Test Locations 369
Measuring Test Signals 371
Assessing Propagation Test Results 372
Cell Overlap Considerations 374
Annotating Access Point Antenna Installation Locations 375
Writing an RF Site Survey Report 376
Summary 377
Chapter 16 Installing and Configuring a Wireless LAN 379
Wireless LAN Installation Considerations 379
Planning the Installation 380
Developing an Installation Plan 380
Points of Contact 380
Safety Tips 381
Installation Procedures 381
Required Facility Changes 382
Tools 382
References to Design Documentation 382
Schedule 383
Resources 383
Budget 383
Risks 383
Coordinating the Installation 383
Staging the Components 384
Installing Access Points 386
Mounting Practices 386
Antenna Alignment 387
Configuring Access Points 387
Configuration Setting Access 388
Firmware 388
Access Point Configuration Settings 388
802.11n/ac Enable 388
SSID 389
Beacon Interval 389
Radio Frequency Bands 390
Transmit Power 390
Transmission Channel 391
Data Rates 392
Antenna Diversity 392
Channel Width 393
Fragmentation Threshold 394
RTS/CTS Threshold 394
Testing the Installation 395
Documenting the Installation 395
Summary 396
Chapter 17 Testing a Wireless LAN 397
Wireless LAN Testing Considerations 397
Signal Coverage Testing 398
Wireless Site Survey Coverage Testing 398
As-Installed Coverage Testing 399
Considering Beacon Rates 399
Performance Testing 400
Association Tests 401
Registration Tests 401
Authentication Tests 401
Network Connection Tests 402
Application Connection Tests 402
Application Tests 402
Load Tests 403
In-Motion Testing 404
Security Vulnerability Testing 405
Security Settings Verification 405
Penetration Testing 405
Private-Side Testing 405
Public-Side Testing 406
Acceptance/Verification Testing 407
Simulation Testing 408
Prototype Testing 409
Pilot Testing 409
Test Documentation 410
Summary 411
Part V: Operational Support Considerations
Chapter 18 Managing a Wireless LAN 413
Operational Support Considerations 413
Help Desk 414
Connection Problems 414
Poor Signal Coverage 415
Poor Performance 415
System Status 415
Additional Considerations 415
Network Monitoring 416
Performance Monitoring 416
Access Point Monitoring 416
Configuration Monitoring 417
Security Policy Management 417
Installation Control Policies 417
Monitoring Policies 418
Periodic Testing Policies 418
Maintenance 418
Inoperative Access Points 418
Poor Performance 418
Poor Signal Coverage 419
Broken Hardware 419
Firmware Updates 419
Signal Coverage Verification 420
Access Point Inspections 420
Troubleshooting 420
Sparing 420
Engineering 421
Advanced Problem Resolution 421
Coverage Expansion 421
Capacity Increases 422
Firmware Review 422
Technology Upgrades 422
Design Review 422
Configuration Management 422
Change-Control Processes 423
Security Management 424
Reviewing Existing Security Policies 424
Reviewing the System Architecture 425
Reviewing Management Tools and Procedures 425
Interviewing Users 425
Verifying Configurations of Wireless Devices 425
Investigating Physical Installations of Access Points 426
Identifying Rogue Access Points 426
Performing Penetration Tests 426
Analyzing Security Gaps 427
Recommending Improvements 427
Trouble Ticket Coordination 427
Help Desk Group 428
Desktop Support Group 428
Network Support Group 428
Preparing for the Transfer to Operational Mode 429
Summary 429
Chapter 19 Troubleshooting a Wireless LAN 431
Troubleshooting Methodology 431
Identifying the Problem 431
Identifying the Underlying Cause of the Problem 432
Fixing the Problem 432
Connection Problems 432
Insufficient Signal Coverage 433
Radio Signal Interference 434
Access Point Failure 434
Incompatible Client Radio 434
Faulty Firmware 435
Incorrect Client Radio Configuration 435
Performance Problems 436
Insufficient Signal Coverage 436
Radio Signal Interference 436
Faulty Firmware 437
Non-optimal Client Radio Configuration 437
Non-optimal Access Point Configuration 437
Misaligned Antennas 438
High Utilization 439
Summary 439
Chapter 20 Preparing Operational Support Staff 441
Support Staff Considerations 441
Availability of Existing Staff 442
Experience Requirements 442
Education and Training Requirements 443
Vendor-Neutral Training 443
Vendor-Specific Training 443
College Education 444
Certifications 444
Staffing Sources 445
Summary 445
Glossary 447
Index 455