Wireless 101 Introduction... xxi Certified Wireless Network Administrator: Official Certification Guide Key Topics...xxi Course Objectives...xxii Course Overview...xxii Unit 1 Introduction to Wireless LANs...1 The Wireless LAN Market...7 History of Wireless LANs...7 Today s Wireless LAN Standards...8 Wireless LAN Specific Standards... 8 Activities... 10 Roles of Wireless LANs... 12 Access Role...12 Network Extension...14 Building-to-Building Connectivity... 15 Last Mile Data Delivery... 17 Mobility... 18 SO/HO... 19 Mobile Offices... 20 Activities... 22 i
Unit 2 RF Fundamentals...29 RF...33 RF Behaviors... 33 Gain... 34 Loss...35 Reflection...36 Refraction...37 Diffraction... 37 Scattering...39 Absorption...40 Activities... 41 VSWR...43 VSWR...44 VSWR Measurements...44 Effects of VSWR... 45 Solutions to VSWR...45 Activities... 46 Principles of Antennas...48 Wireless LAN Antenna Principles...48 LOS...49 Fresnel Zone...50 Obstructions...50 Antenna Gain...51 ii
IR...52 EIRP...53 Activities... 54 RF Mathematics...57 RF Power Calculations...57 Units of RF Power Measurement...58 Watts... 58 Milliwatt...59 Decibels... 59 Gain and Loss Measurements...60 dbm... 61 Examples...63 dbi... 63 Example...64 Accurate Measurements...65 Activities... 66 Summary...68 Quiz...69 Unit 3 Spread Spectrum Technology...75 Introducing Spread Spectrum...79 Narrowband Transmission... 79 Spread Spectrum Technology...81 Uses of Spread Spectrum...81 Wireless LANs...82 WPANs... 83 WMANs... 84 FCC Specifications...84 Activities... 85 FHSS...87 How FHSS Works...87 Effects of Narrowband Interference... 88 Frequency-Hopping Systems...89 Channels... 89 Dwell Time...90 Hop Time... 91 Dwell Time Limits... 91 FCC Rules Governing FHSS Systems...92 Activities... 94 iii
DSSS...96 How DSSS Works...96 Direct Sequence Systems...97 Channels... 98 Effects of Narrowband Interference... 100 FCC Rules Affecting DSSS...100 Activities... 101 Comparing FHSS and DSSS...103 Determining Factors Driving Spread Spectrum Technology Choices...103 Narrowband Interference Present in the Environment... 104 Cost of FHSS and DSSS Systems...104 Co-location for Failover, Load Balancing, and Added Capacity... 104 Equipment Compatibility and Availability... 105 Data Rate and Throughput... 106 Security...106 Standards Support... 107 Activities... 108 Summary...110 Quiz...111 Unit 4 Wireless LAN Infrastructure Devices...117 Access Points...125 What Is a Wireless Access Point?... 126 Access Point Modes...127 Root Mode... 127 Bridge Mode...128 Repeater Mode... 128 Common Access Point Options... 129 Fixed or Detachable Antennas...130 Advanced Filtering Capabilities...130 Removable (Modular) Radio Cards... 130 Variable Output Power...131 Varied Types of Wired Connectivity...131 Access Point Configuration and Management...132 Mounting... 134 Activities... 136 iv
Wireless Bridges...138 What Is a Wireless Bridge?... 138 Wireless Bridge Modes... 139 Root Mode... 140 Nonroot Mode... 140 Access Point Mode...141 Repeater Mode... 141 Common Bridge Options... 142 Fixed or Detachable Antennas...142 Advanced Filtering Capabilities...142 Removable (Modular) Radio Cards... 143 Variable Output Power...143 Varied Types of Wired Connectivity...143 Configuration and Management... 144 Activities... 145 Wireless Workgroup Bridges...147 What Is a Wireless Workgroup Bridge?... 147 Common Options...149 Configuration and Management... 149 Activities... 150 Wireless LAN Client Devices...152 Types of Wireless Client Devices... 152 PCMCIA and Compact Flash Radio Cards...153 Wireless Ethernet and Serial Converters... 154 USB Adapters... 155 PCI and ISA Adapters...156 Configuration and Management... 156 Driver Installation... 156 Manufacturer Utilities... 157 Site Survey Tools...157 Spectrum Analyzer... 157 Power and Speed Monitoring Tools... 157 Profile Configuration Utilities... 157 Link Status Monitor with Link Testing Functionality... 158 Common Utility Functionality... 158 Activities... 159 Lesson 5 Wireless Residential Gateways...161 What Is a Wireless Residential Gateway?...161 Common Options...163 Configuration and Management... 164 Activities... 165 v
Lesson 6 Enterprise Wireless Gateways...167 Enterprise Wireless Gateway Features...168 Configuration and Management... 170 Activities... 171 Summary...173 Quiz...174 Unit 5 Antennas and Accessories...179 RF Antennas...184 RF Antenna Categories... 184 Omnidirectional (Dipole) Antennas... 185 Usage...188 Semidirectional Antennas... 189 Usage...190 Highly Directional Antennas...191 Usage...192 RF Antenna Concepts... 193 Polarization... 193 Practical Use... 195 Gain... 196 Beamwidth...196 Free Space Path Loss...198 The 6dB Rule... 198 Antenna Installation...199 Placement...199 Mounting...200 Antenna Mounting Options...200 Mounting Aesthetics...201 Appropriate Use... 201 Orientation...201 Alignment... 201 Safety... 202 Follow the Manual... 202 Do Not Touch When Power is Applied...202 Use Professional Installers...202 Keep Antennas Away from Metal Obstructions... 202 Keep Antenna Towers Away from Power Lines... 203 Use Grounding Rods...203 Maintenance... 203 Activities... 204 vi
PoE Devices...208 When to Use PoE... 208 Common PoE Options... 209 Single-Port DC Voltage Injectors...210 Multiport DC Voltage Injectors...210 Active Ethernet Switches... 211 PoE Compatibility...212 Types of Injectors...213 Types of Pickers/Taps...213 Voltage and Pinout Standards... 213 Fault Protection... 214 Activities... 215 Wireless LAN Accessories...217 Wireless LAN Accessory Types... 217 RF Amplifiers... 218 Common Options...219 Configuration and Management... 220 Special Stipulations...220 RF Attenuators... 222 Common Options...223 Configuration and Management... 224 Lightning Arrestors... 224 Common Options...226 Configuration and Maintenance... 227 RF Splitters... 228 Choosing an RF Splitter... 229 RF Connectors... 231 Choosing an RF Connector...232 RF Cables... 233 RF Pigtail Adapter Cable...235 Frequency Converters... 236 Bandwidth Control Units... 237 Test Kits... 239 Activities... 240 Summary...243 Quiz...244 vii
Unit 6 Wireless LAN Organizations and Standards...251 FCC...256 ISM and UNII Bands... 256 Advantages and Disadvantages of License-Free Bands... 257 ISM Bands... 258 900-MHz ISM Band... 258 2.4-GHz ISM Band... 258 5.8-GHz ISM Band... 258 UNII Bands... 259 Lower Band...259 Middle Band...259 Upper Band... 260 Power Output Rules... 260 PtMP...260 PtP... 261 Activities... 263 IEEE...266 IEEE Wireless LAN Standards... 266 IEEE 802.11... 266 IEEE 802.11b... 267 IEEE 802.11a... 268 IEEE 802.11g... 269 Activities... 270 Major Organizations...272 WECA... 272 ETSI... 273 WLANA... 274 Activities... 275 Competing Technologies...277 HomeRF...277 Bluetooth...279 IrDA...279 Infrared...280 Security... 280 Stability...280 WLIF...281 Activities... 282 Summary...284 Quiz...285 viii
Unit 7 The 802.11 Network Architecture...291 Locating a Wireless LAN...297 Service Set Identifier... 297 Beacons... 298 Time Synchronization... 298 FH or DS Parameter Sets...298 SSID Information...299 TIM...299 Supported Rates... 299 Passive Scanning...299 Active Scanning...301 Activities... 303 Authentication and Association...305 Authentication... 305 Association... 306 States of Authentication and Association...307 Unauthenticated and Unassociated...307 Authenticated and Unassociated...307 Authenticated and Associated... 307 Authentication Methods...308 Open System Authentication...308 Open System Authentication Process...309 Shared Key Authentication... 310 Shared Key Authentication Process... 310 Authentication Security... 311 Shared Secrets and Certificates...312 Emerging Wireless Security Solutions...312 802.1x and EAP... 312 VPN Solutions... 316 Activities... 318 Service Sets...320 BSS...321 ESS...322 IBSS... 323 Roaming... 324 Standards... 325 Connectivity... 327 Reassociation... 327 VPN Use... 328 Layer 2 and Layer 3 Boundaries...329 Load Balancing...332 Activities... 333 ix
Power Management Features...335 Power Management Modes...335 CAM...335 PSP Mode... 336 PSP Mode in a BSS... 336 PSP in an IBSS...337 Activities... 340 Summary...342 Quiz...343 Unit 8 Physical Layers...349 How Wireless LANs Communicate...355 Wireless LAN Frames vs. Ethernet Frames... 355 Collision Handling... 358 Fragmentation...359 DRS... 360 DCF... 361 PCF... 362 The PCF Process... 362 Activities... 363 Interframe Spacing...365 Three Types of Spacing...366 SIFS...367 PIFS...367 DIFS... 368 Slot Times...368 The Communications Process...369 Activities... 373 RTS/CTS...375 Use of RTS/CTS on a Wireless Network... 375 Configuring RTS/CTS... 377 Activities... 378 Modulation...380 Modulation and Spreading Code Types...380 Activities... 383 Summary...385 Quiz...386 x
Unit 9 Troubleshooting Wireless LAN Installations...391 Multipath...393 Causes of Multipath... 393 Effects of Multipath...394 Decreased Signal Amplitude... 394 Corruption...395 Nulling...396 Increased Signal Amplitude...397 Troubleshooting Multipath... 398 Solutions for Multipath...398 Activities... 401 Hidden Node...403 Causes of Hidden Node...403 Troubleshooting Hidden Node...405 Solutions for Hidden Node...405 Use RTS/CTS...406 Increase Power to the Nodes... 406 Remove Obstacles...407 Move the Node...407 Activities... 408 Near/Far...410 Causes of Near/Far...411 Troubleshooting Near/Far...412 Solutions for Near/Far...412 Activities... 413 System Throughput...415 Sources of Overhead... 415 Distance... 416 Hardware... 416 Spread Spectrum Technology... 416 User Count...416 PCF Mode...417 Other Factors... 417 Co-location Throughput (Theory vs. Reality)...417 Theory: What Should Happen...418 Reality: What Does Happen...419 xi
Solutions for Co-location Throughput Problems...420 Use Two Access Points...420 Use 802.11a Equipment... 421 Issues with 802.11a Equipment... 422 Summary...422 Activities... 423 Lesson 5 Types of Interference...425 RF Interference Sources...425 Narrowband...425 All-Band Interference... 428 Weather...429 Wind...430 Stratification...431 Lightning... 431 Adjacent Channel and Co-channel Interference... 431 Adjacent Channel Interference... 431 Co-channel Interference... 432 Activities... 435 Lesson 6 Range Considerations...437 Issues that Affect RF Signal Range...437 Transmission Power...437 Antenna Type...437 Environment... 438 Activities... 439 Summary...440 Quiz...441 Unit 10 Wireless LAN Security...447 WEP...451 What Is WEP?... 451 Why WEP Was Chosen...452 WEP Keys...453 Static WEP Keys... 455 Centralized Encryption Key Servers...456 WEP Usage... 457 AES...458 Filtering...458 SSID Filtering... 459 MAC Address Filtering...461 Circumventing MAC Filters...462 xii
Protocol Filtering... 463 Activities... 464 Attacks on Wireless LANs...466 Attack Methods...466 Passive Attacks... 467 Active Attacks...468 Jamming...470 Man-in-the-Middle Attacks... 471 Activities... 474 Emerging Security Solutions...476 Vendor Solutions...476 WEP Key Management...477 Wireless VPNs...477 TKIP... 479 AES-Based Solutions...479 Wireless Gateways... 479 802.1x and EAP... 480 Activities... 483 Corporate Security Policy...485 Components of a Corporate Security Policy... 485 Keep Sensitive Information Private... 486 Physical Security...486 Wireless LAN Equipment Inventory and Security Audits... 487 Using Advanced Security Solutions...488 Public Wireless Networks...488 Limited and Tracked Access...489 Activities... 490 Lesson 5 Security Recommendations...492 WEP...492 Cell Sizing... 493 User Authentication... 494 Security Needs...494 Use Additional Security Tools...495 Monitoring for Rogue Hardware...495 Switches, Not Hubs...495 Wireless DMZ... 496 Firmware and Software Updates...496 Activities... 497 Summary...499 Quiz...500 xiii
Unit 11 Site Survey Fundamentals...505 RF Site Surveys...508 What Is a Site Survey?...508 Activities... 510 Preparing for a Site Survey...512 Presurvey Questions... 512 Facility Analysis... 513 Existing Networks Analysis... 514 Area Usage and Towers Analysis... 516 Purpose and Business Requirements Analysis... 518 Bandwidth and Roaming Requirements Analysis... 519 Available Resources...522 Security Requirements... 524 Preparation Exercises...525 Preparation Checklist... 526 Activities... 527 Site Survey Equipment...529 Types of Site Survey Equipment...529 Access Point... 530 PC Card and Utilities...530 Laptops and PDAs... 532 Paper...533 Outdoor Surveys...534 Spectrum Analyzer...534 Network Analyzer ( Sniffer )...536 Site Survey Kit Checklist...537 Activities... 540 Conducting a Site Survey...542 Indoor Surveys... 542 Outdoor Surveys... 543 Before You Begin...544 RF Information Gathering... 545 Range and Coverage Patterns...545 Data Rate Boundaries...548 Documentation... 549 Throughput Tests and Capacity Planning...549 Interference Sources...550 Obstacle-Induced Signal Loss... 551 xiv
Wired Data Connectivity and AC Power Requirements... 554 Outdoor Antenna Placement...555 Spot Checks... 555 Activities... 556 Lesson 5 Site Survey Reporting...558 Preparing the Report...558 Report Format...558 Purpose and Business Requirements... 559 Methodology... 559 RF Coverage Areas... 559 Throughput... 559 Interference... 560 Problem Areas...560 Drawings... 560 Hardware Placement and Configuration Information... 561 Additional Reporting... 561 Activities... 564 Summary...566 Quiz...567 Course Quiz...573 Glossary...585 Index...609 Notes...623 xv