Designing and Deploying 802.11 Wireless Networks: A Practical Guide to Implementing 802.11n and 802.11ac Wireless Networks For Enterprise-Based Applications, 2nd Edition

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 distribution system for maximum reliability, manageability, and performance
• Make the right tradeoffs and decisions to optimize range, performance, and roaming
• Secure WLANs via encryption, authentication, rogue AP detection, RF shielding, and policies
• Master design and site survey tools and methods for planning 802.11ac networks and migrations
• Efficiently install and test any 802.11ac or 802.11n wireless network
• Establish specialized support for wireless networks, including help desk operations
• Systematically troubleshoot connectivity, performance, and roaming issues
• Design efficient mesh networks and city-wide deployments

Table of Contents

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
    

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