Designing and Deploying 802.11 Wireless Networks

Introduction xxvPart I: Fundamental ConceptsChapter 1 Introduction to Wireless LANs 1Wireless LAN Markets and Applications 1Retail 2Warehousing 2Healthcare 4Hospitality 5Voice over WLAN 5Video Surveillance 6Home and Small Office 7General Enterprise Systems 8Location-Aware Wireless Applications 8Benefits of Wireless Networks 10Mobility 10Installation in Difficult-to-Wire Areas 11Increased Reliability 11Reduced Installation Time 12Long-Term Cost Savings 12Productivity Gain Is the Answer 12Wireless LAN Technologies 14Initial 802.11 16802.11a 16802.11b 16802.11g 17Current Standards: 802.11n and 802.11ac 18Comparison of 802.11 Standards 19Wi-Fi Certification 19Wireless LANs: A Historical Perspective 21The Early Days 21Initial 802.11 Standardization 22802.11n and 802.11ac Standardization 23Summary 25Chapter 2 Radio Wave Fundamentals 27Radio Wave Attributes 27Amplitude 28Frequency 28Phase 29RF System Components 29RF Transceiver 29RF Modulation 30Amplitude-Shift Keying 31Frequency-Shift Keying 32Phase-Shift Keying 33Quadrature Amplitude Modulation 33Spread Spectrum 33Orthogonal Frequency-Division Multiplexing 36RF Signal Propagation 36Attenuation 37Free Space Loss 37Physical Obstacles 38Multipath Propagation 39Noise and Signal-to-Noise Ratio 39RF Mathematics 41Converting Units 41Summary 42Chapter 3 Wireless LAN Types and Components 43Types of Wireless LANs 43Ad Hoc Wireless LANs 43Infrastructure Wireless LANs 45Wireless Mesh Networks 48Wireless LAN Components 50Client Devices 50Client Radio 51Industry Standard Architecture 53Peripheral Component Interconnect 54Mini-PCI 54PC Card 54ExpressCard 55CompactFlash 55Universal Serial Bus 55Access Points 56Autonomous Access Points 56Controller-Based Access Points 57Wi-Fi Routers 58Mesh Nodes 60Antennas 60RF Amplifiers 62Repeaters 63Bridges 64Network Infrastructure Components 65Network Distribution Systems 65Switches 65Optical Fiber 67Power over Ethernet 67Application Connectivity Software 70Terminal Emulation 70Browser-Based Approaches 71Direct Database Interfaces 72Wireless Middleware 72Summary 74Chapter 4 Wireless LAN Implications 75Security Vulnerabilities 75Passive Monitoring 76Unauthorized Access 79Unauthorized Access Leads to Compromise of Financial Data 82Denial-of-Service Attacks 83Radio Signal Interference 85Microwave Oven Interference 86Cordless Phone Interference 88Bluetooth Interference 90Neighboring Wireless LAN Interference 92Impacts of Multipath Propagation 95Roaming Issues 96Battery Limitations 97Interoperability Problems 98Installation Issues 98Summary 99Part II: The 802.11 StandardChapter 5 Introduction to IEEE 802.11 and Related Standards 101The Importance of Standards 101Types of Standards 102Institute of Electrical and Electronics Engineers 103Benefits of the 802.11 Standard 104Appliance Interoperability 104Fast Product Development 105Stable Future Migration 105Price Reductions 106Avoiding Silos 106The IEEE 802 LAN Standards Family 107802.11 MAC Sublayer 109802.11 Physical Layer 110IEEE 802.2 110Unacknowledged Connectionless Service 111Connection-Oriented Service 112Continuous ARQ 113Stop-and-Wait ARQ 114Acknowledged Connectionless Service 115IEEE 802.11 Features 116Station Services 117Authentication 117Deauthentication 118Privacy 118Distribution System Services 118Association 118Disassociation 118Distribution 118Integration 119Re-association 119Station States and Corresponding Frame Types 119Summary 121Chapter 6 IEEE 802.11 Medium Access Control (MAC) Layer 123Primary 802.11 MAC Layer Functions 123Data Delivery 124Medium Access 125Distributed Coordination Function 126Hybrid Coordination Function 127Error Recovery 129Data Frame Acknowledgements 129Dynamic Rate Switching 130Data Frame Aggregation 131MSDU Aggregation 132MPDU Aggregation 132Data Frame Fragmentation 132Encryption 134Wired Equivalent Privacy 134Temporal Key Integrity Protocol 135CCMP 136Multicasting 136Connectivity 138Scanning for Networks 138Authentication 140Open System Authentication 140Shared Key Authentication 141IEEE 802.1X Port-Based Authentication 142Associating with the Access Point 1434-Way Handshake 145Timing and Synchronization 145Short IFS 146PCF IFS 146DCF IFS 147Extended IFS 147RTS/CTS 147Power Management 149802.11 MAC Frame Structures 150Protocol Version Field 150Type Field 150Subtype Field 151To DS Field 152From DS Field 152More Frag Field 152Retry Field 153Power Management Field 153More Data Field 153Protected Frame Field 153Order Field 153Duration/ID Field 153Address 1, 2, 3, and 4 Fields 154Sequence Control Field 154QoS Control Field 155HT Control Field 155Frame Body Field 155Frame Check Sequence Field 155MAC Frame Types 156Management Frames 156Association Request Frame 156Association Response Frame 156Re-association Request Frame 157Re-association Response Frame 157Probe Request Frame 157Probe Response Frame 157Beacon Frame 157ATIM Frame 159Disassociation Frame 159Authentication Frame 159Deauthentication Frame 160Action Frame 160Action No ACK Frame 160Management Frame Body Contents 160Control Frames 162Control Wrapper Frame 162Block ACK Request Frame 162Block ACK Frame 162Power-Save Poll Frame 162Request-to-Send Frame 162Clear-to-Send Frame 162Acknowledgement Frame 163Contention-Free End Frame 163CF End + CF ACK Frame 163Data Frames 163Interoperability 164Summary 165Chapter 7 IEEE 802.11 Physical (PHY) Layers 167802.11 Physical Layer Architecture 167PLCP Sublayer 168PMD Sublayer 168802.11 Physical Layer Functions 169Carrier Sense Function 169Transmit Function 169Receive Function 170Legacy 802.11 Physical Layers 170Frequency-Hopping Spread Spectrum PHY 170Direct-Sequence Spread Spectrum PHY 172Infrared PHY 175Orthogonal Frequency-Division Multiplexing PHY (802.11a) 175High-Rate Direct-Sequence Spread Spectrum PHY (802.11b) 178Extended-Rate PHY (802.11g) 180High-Throughput (802.11n) 180MIMO Concepts 180Transmit Beamforming 180Spatial Multiplexing 181Channel Bonding 183802.11n Modulation 184Interoperability 188Very High-Throughput 6 GHz (802.11ac) 188RF Channel Bandwidth 188Multi-User MIMO 189Interoperability 189Summary 190Part III: Wireless Network DesignChapter 8 Planning a Wireless LAN Deployment 191Project Management Principles 191Wireless LAN Deployment Planning Steps 193Step 1: Defining the Project Scope 194Project Charter 194Assumptions 194Constraints 194Step 2: Developing the Work Breakdown Structure 196Requirements Definition Phase 196Design Phase 197Implementation Phase 199Operations and Maintenance Phase 201Step 3: Identifying Staffing 204Step 4: Creating a Schedule 206Step 5: Developing a Budget 207Preliminary Requirements and Design 207Hardware and Software Costs 208Deployment Services Costs 211Ongoing Operations and Maintenance Costs 212Step 6: Evaluating Risks 215Step 7: Analyzing Feasibility 217Costs 217Benefits 218Impacts on Users 218Impacts on Existing Systems 219Making the Decision to Proceed 219Executing the Project 221The Kickoff Meeting 222Evaluating the Outcome of the Project 223Summary 225Chapter 9 Defining Requirements for a Wireless LAN 227Requirements Attributes 227Requirements Definition Steps 228Step 1: Gathering Information 229Interviewing Users 229Interviewing IT Staff 230Reviewing the Existing Infrastructure and Systems 230Step 2: Analyzing Requirements 231Application Requirements 231Client Device Requirements 233Signal Coverage Requirements 234Utilization Requirements 236Mobility Requirements 238Security Requirements 240Scalability Requirements 243Existing Network Infrastructure Requirements 244Environmental Requirements 245Aesthetic Requirements 248Step 3: Documenting Requirements 248Step 4: Obtaining Requirements Approval 249Summary 250Chapter 10 System Architecture Considerations 251Architectural Considerations 251Wireless Access Networks 252Autonomous Access Point Architecture 253Controller-Based Access Point Architecture 254Mesh Network Architecture 256Ad Hoc Architecture 2582.4-GHz Versus 5-GHz 259Geographic Location Considerations 260Performance Considerations 260Existing Client Device Considerations 260Facility Size Considerations 260Radio Signal Interference Considerations 261Hybrid Frequency Band Considerations 261Common Infrastructure Considerations 262Migration Considerations 264Redundancy Considerations 264Controller Redundancy 264Access Point Redundancy 267Distribution Systems 269Switch Considerations 269PoE Considerations 269Voice over WLAN Systems 271Single-Site Architecture 271Multisite WAN with Centralized Call Processing 272Multisite WAN with Distributed Call Processing 274Application Connectivity 277Terminal Emulation Considerations 277Browser-Based Connectivity Considerations 279Direct Database Considerations 280Wireless Middleware Considerations 282Summary 285Chapter 11 Range, Performance, and Roaming Considerations 287Range Versus Performance 287Range Considerations 288Signal Coverage Requirements 288Radio Frequency Bands 289Transmit Power Settings 290Transmission Channel Settings 291Data Rate Settings 292Antennas 294Amplifiers 295Repeaters 296Physical Obstacles 297Radio Signal Interference 297Performance Considerations 299Throughput Versus Data Rate 299Radio Frequency Bands 300Transmit Power Settings 300Transmission Channel Settings 301Data Rate Settings 302Antennas 302Amplifiers 303Radio Signal Interference 304Channel Width Settings 304Signal Coverage 305Fragmentation Settings 305RTS/CTS Settings 306Bandwidth Control Mechanisms 306Microcell Deployment Strategies 307Roaming Considerations 309Roaming Levels 309Access Point Roaming 310Subnet Roaming 310Wireless ISP Roaming 312Wireless IP Phone Roaming 312Mobility Settings 313Summary 313Chapter 12 Radio Frequency Considerations 315Frequency Band Selection 3152.4-GHz Frequency Band 3155-GHz Frequency Band 316Transmission Channel Settings 316Manual Channel Settings 316Single-Level Facilities 317Multilevel Facilities 319Adaptive Channel Settings 321Difficult-to-Cover Areas 321Signal Coverage in Elevators 322Signal Coverage in Stairwells 324Signal Coverage in Parking Areas 324Radio Signal Interference Reduction 325Summary 326Chapter 13 Security Considerations 327Security Elements 327Encryption 328Authentication 330EAP Methods 331Authentication Servers 332Guest Access 333Rogue Access Point Detection 334RF Shielding 335Wireless Security Policies 337Summary 339Part IV: Wireless Network Installation and TestingChapter 14 Test Tools 341Tool Considerations 341Spectrum Analyzers 342Real-Time Fast Fourier Transform 342FFT Duty Cycle 344Swept Spectrogram 345Active Devices 345Recording Spectrum Data 346Signal Coverage Testers 346Heat Maps 346Positioning 347Passive Versus Active Modes 349Simulation 349Free Signal Coverage Tester: NetStumbler 349Wireless Protocol Analyzers 350Filtering Frames 351Recording Traces 352Free Protocol Analyzer: WireShark 352Summary 354Chapter 15 Performing a Wireless Site Survey 355Wireless Site Survey Considerations 356Reviewing Requirements 357Selecting Site Survey Tools 358Obtaining Floor Diagrams 359Inspecting the Facility 360Assessing the Existing Network Infrastructure 360Communications Rooms 360Switches and Power over Ethernet 361WAN 361Identifying Potential Radio Signal Interference 361Defining Signal Values for Acceptable Signal Coverage 364Minimum Received Signal Strength 364Minimum SNR 364Uplink Versus Downlink Signal Values 365Identifying Optimum Access Point Antenna Installation Locations 367Propagation Testing 367Test Access Point Configuration 367Antenna Considerations 368Identifying Test Locations 369Measuring Test Signals 371Assessing Propagation Test Results 372Cell Overlap Considerations 374Annotating Access Point Antenna Installation Locations 375Writing an RF Site Survey Report 376Summary 377Chapter 16 Installing and Configuring a Wireless LAN 379Wireless LAN Installation Considerations 379Planning the Installation 380Developing an Installation Plan 380Points of Contact 380Safety Tips 381Installation Procedures 381Required Facility Changes 382Tools 382References to Design Documentation 382Schedule 383Resources 383Budget 383Risks 383Coordinating the Installation 383Staging the Components 384Installing Access Points 386Mounting Practices 386Antenna Alignment 387Configuring Access Points 387Configuration Setting Access 388Firmware 388Access Point Configuration Settings 388802.11n/ac Enable 388SSID 389Beacon Interval 389Radio Frequency Bands 390Transmit Power 390Transmission Channel 391Data Rates 392Antenna Diversity 392Channel Width 393Fragmentation Threshold 394RTS/CTS Threshold 394Testing the Installation 395Documenting the Installation 395Summary 396Chapter 17 Testing a Wireless LAN 397Wireless LAN Testing Considerations 397Signal Coverage Testing 398Wireless Site Survey Coverage Testing 398As-Installed Coverage Testing 399Considering Beacon Rates 399Performance Testing 400Association Tests 401Registration Tests 401Authentication Tests 401Network Connection Tests 402Application Connection Tests 402Application Tests 402Load Tests 403In-Motion Testing 404Security Vulnerability Testing 405Security Settings Verification 405Penetration Testing 405Private-Side Testing 405Public-Side Testing 406Acceptance/Verification Testing 407Simulation Testing 408Prototype Testing 409Pilot Testing 409Test Documentation 410Summary 411Part V: Operational Support ConsiderationsChapter 18 Managing a Wireless LAN 413Operational Support Considerations 413Help Desk 414Connection Problems 414Poor Signal Coverage 415Poor Performance 415System Status 415Additional Considerations 415Network Monitoring 416Performance Monitoring 416Access Point Monitoring 416Configuration Monitoring 417Security Policy Management 417Installation Control Policies 417Monitoring Policies 418Periodic Testing Policies 418Maintenance 418Inoperative Access Points 418Poor Performance 418Poor Signal Coverage 419Broken Hardware 419Firmware Updates 419Signal Coverage Verification 420Access Point Inspections 420Troubleshooting 420Sparing 420Engineering 421Advanced Problem Resolution 421Coverage Expansion 421Capacity Increases 422Firmware Review 422Technology Upgrades 422Design Review 422Configuration Management 422Change-Control Processes 423Security Management 424Reviewing Existing Security Policies 424Reviewing the System Architecture 425Reviewing Management Tools and Procedures 425Interviewing Users 425Verifying Configurations of Wireless Devices 425Investigating Physical Installations of Access Points 426Identifying Rogue Access Points 426Performing Penetration Tests 426Analyzing Security Gaps 427Recommending Improvements 427Trouble Ticket Coordination 427Help Desk Group 428Desktop Support Group 428Network Support Group 428Preparing for the Transfer to Operational Mode 429Summary 429Chapter 19 Troubleshooting a Wireless LAN 431Troubleshooting Methodology 431Identifying the Problem 431Identifying the Underlying Cause of the Problem 432Fixing the Problem 432Connection Problems 432Insufficient Signal Coverage 433Radio Signal Interference 434Access Point Failure 434Incompatible Client Radio 434Faulty Firmware 435Incorrect Client Radio Configuration 435Performance Problems 436Insufficient Signal Coverage 436Radio Signal Interference 436Faulty Firmware 437Non-optimal Client Radio Configuration 437Non-optimal Access Point Configuration 437Misaligned Antennas 438High Utilization 439Summary 439Chapter 20 Preparing Operational Support Staff 441Support Staff Considerations 441Availability of Existing Staff 442Experience Requirements 442Education and Training Requirements 443Vendor-Neutral Training 443Vendor-Specific Training 443College Education 444Certifications 444Staffing Sources 445Summary 445Glossary 447Index 455