Contents Introduction to Wide Area Networks Introduction to Wide Area Networks Preface...i Prerequisites...i Key Topics...ii Course Objectives...ii Pedagogical Features...iii Learning Objectives, Unit Summaries, Discussion Questions, and Activities/Exercises...iii Key Terms...iii Supplements...iii Advancing Your Level of Technical Expertise...iv Why Choose WestNet?...iv Introduction... xxi Course Overview...xxii Unit 1 Fundamentals of WANs...1 Classification of Networks...10 LANs... 10 Campus Networks...11 MANs...12 WANs... 12 Activities... 14 i
Introduction to Wide Area Networks Telecommunications...17 Development of the Telecommunications Network... 17 More Than Just Words... 19 Activities... 20 Voice Networks...22 Connectivity of the Analog Network... 22 Reduction of Trunk Lines... 24 Activities... 26 Voice Network Technology...28 Analog Technology...28 Early Telephones...30 FDM...30 Duplexing... 33 PBXs...34 Activities... 35 Lesson 5 PBX Fundamentals...38 PBX Components... 38 Trunks...39 Extension Lines... 40 Equipment Cabinet... 40 Telephones and Attendant Console... 41 Administrative Terminal... 41 Making a Call on a PBX... 41 Call Routing... 42 Supplementary PBX Features... 42 DID...43 DISA... 43 Station Set Features...43 Attendant Console Services... 44 Administration and Management Reports...45 CDRs...45 Test Reports... 46 Busy-Hour Studies... 46 PBX Enhancements...46 Voice Response...46 Voice Recognition... 47 Call Following... 47 ACD... 47 Other Auxiliary Equipment...48 PBX Costs and Requirements... 48 Activities... 49 ii
Contents Lesson 6 PBX Features and Functions...52 Call Accounting... 52 Authorization Codes... 53 Account Codes...53 Voice Mail Systems... 54 Design Factors... 55 Unified Messaging... 56 Broadcasting...56 Voice Mail Security... 56 Automated Attendants... 57 CoR... 58 Call Pickup... 58 Call Park... 58 Call Forwarding...59 Call Announcement... 59 Call Waiting... 59 DAU...59 Activity... 60 Lesson 7 Computer Data and the Voice Network...62 Analog and Digital Signals... 62 Modems...64 Activities... 66 Lesson 8 Digitizing the Voice...67 Analog to Digital...68 Mixing It Up... 69 TDM...70 WDM...71 Activities... 72 Lesson 9 Integration of Services...74 Ones and Zeros... 74 Data Transfer...75 Voice Conversations...75 Activities... 76 0 Elements of the Telecommunications Business...78 The Players... 78 IXCs... 79 RBOCs/LECs...79 CLECs...79 CAPs...80 Regulated Competition...81 iii
Introduction to Wide Area Networks iv An Expanded Role for the FCC... 81 LNP...82 Shared Platforms... 82 Network Interconnection...82 Unbundled Local Loops...82 Reciprocal Compensation... 83 Tariffs... 83 Effects of Competition... 84 Legal Struggles... 84 Price Pressure... 85 Slamming...85 Niche Companies...85 Activities... 86 Unit 2 WAN Concepts and Components...95 Physical and Logical Circuits...106 Circuits and Virtual Circuits...106 PVCs and SVCs...108 SVC Information Transfer...110 Activities... 111 Connecting to WAN Circuits...113 DCE...113 DTE-to-DCE Protocols...114 Layer Upon Layer...115 Activities... 117 Connecting to Analog Networks...118 Modem Concepts... 118 Internal vs. External Modems...119 UART...120 RS-232... 120 Modem Signals... 122 Activities... 123 Analog Modems...125 Modem Protocols... 125 Modulation... 126 FM...127 AM... 128 PM... 129 Modem Operations...129 Activities... 132
Contents Lesson 5 Modem Compatibility...135 Timing is Everything...135 Data Compression and Error Control...137 Modem Compatibility... 138 AT&T Compatibility...138 CCITT Compatibility...139 Hayes Compatibility... 139 Activities... 140 Lesson 6 Connecting to Digital Networks...143 DTE/CSU Interface... 143 Smart Jack... 144 Subrate Facilities... 144 DDS... 145 Activities... 146 Lesson 7 Microwave Communications...148 Fundamentals of Microwave Communications...148 Microwave Components...150 MUXs... 151 Modems... 151 Transmitters/Receivers...151 Antenna Equipment...151 Activities... 152 Lesson 8 Satellite Communications...154 Linking to a Satellite...154 Satellite Equipment...155 Satellite Frequency Ranges... 155 Satellite Characteristics...156 Satellites and Orbits... 157 Bandwidth...158 Satellite Protocols... 158 Satellite Use...160 Activities... 161 Lesson 9 End-to-End Connectivity...164 WAN Applications...164 Activities... 167 v
Introduction to Wide Area Networks Unit 3 Physical Layer WAN Protocols...173 Summary of Data Rates...181 Point-to-Point Links... 181 Various Data Rates and Associated Applications... 183 Bandwidth...184 Activities... 186 Dial-Up and Leased Lines...188 Dial-Up Connections... 188 Leased Lines... 189 DDS... 190 Activities... 192 SW56...194 SW56 Service...194 SW56 Operation... 195 Activity... 197 VSAT...198 VSAT Use...198 Satellite Applications...200 Activities... 201 Lesson 5 T-Carriers and E-Carriers...203 T1, FT1, and T3...203 T1...206 FT1...209 T3 and North American Digital Hierarchy...210 Signal Shapes and Codes... 211 T1 Signaling... 213 Cabling...214 Connectors...216 Applications...218 Circuit Costs... 220 Activities... 221 Lesson 6 ADSL...223 Fundamentals of ADSL... 223 DSLs and Internet Access... 227 Why High-Speed Local Loop Is Hot...227 vi
Contents Options for Local High-Speed Internet Access...228 Activities... 231 Lesson 7 Cable Modems...233 Cable Modem Technology... 233 ADSL or Cable Modem? The Subscriber s Perspective... 235 Activities... 237 Lesson 8 SONET...239 SONET Standard... 239 SONET Advantages... 240 SONET Protocol Architecture... 241 Path Layer...242 Line Layer...242 Section Layer... 243 Photonic Layer...244 SONET Multiplexing...244 SONET Frame Format... 246 SONET Network Elements...249 Activities... 252 Unit 4 Data Link Layer WAN Protocols...259 A Layer Above...262 Data Link Layer Protocols...262 Reliable WAN Networks... 263 Activities... 266 HDLC...267 HDLC Operation...268 HDLC Protocol... 269 Activities... 274 SLIP and PPP...275 SLIP... 275 CSLIP...276 PPP...277 Activities... 280 End-to-End Connectivity...281 Connecting to the Internet...281 Activity... 283 vii
Introduction to Wide Area Networks viii Unit 5 Higher-Layer WAN Protocols...287 ISDN Concepts...294 IDNs...294 ISDN Services...295 Activities... 298 ISDN Protocols...300 Fundamentals of ISDN Protocols... 300 Physical Attachment to ISDN... 302 Data Link Layer Call Setup, LAPD...302 Network Layer Call Control, I.451... 302 Network Layer Packet-Switching, X.25... 302 ISDN CPE...303 ISDN Reference Points... 304 Activities... 306 ISDN Implementation...308 ISDN Applications...308 Basic Network Connectivity...309 Internetworking of Remote Offices... 309 Dial-on-Demand Remote Networking...311 Network Redundancy and Overflow...312 Activities... 313 Frame Relay Concepts...315 What Is Frame Relay?... 316 Frame Relay Terms... 318 Activities... 319 Lesson 5 Frame Relay Protocols...321 Permanent and Virtual Circuits... 321 Frame Relay Frame... 322 Frame Relay Addressing... 326 Interconnecting LANs Using Frame Relay... 328 Activities... 329 Lesson 6 Frame Relay Implementation...331 Frame Relay Implementation Options...331 Private Frame Relay... 332 Public Frame Relay...333 Hybrid Frame Relay... 334
Contents End-User Access to Frame Relay Networks...334 Frame Relay vs. Private Line Networking...335 Frame Relay Services...337 Public Frame Relay Services... 337 Bandwidth on Demand...338 Conditional Bursting... 339 Carrier Choice...340 Frame Relay Network Requirements...341 Activities... 342 Lesson 7 X.25...345 X.25 Services...345 Addressing... 346 X.25 Protocols...346 PLP... 347 LAPB...347 X.21 and X.21bis... 347 PADs... 348 PLP...349 Overhead and Performance Limitations...351 Activity... 353 Unit 6 WAN Solutions...361 ATM Concepts...369 The Need for ATM...370 ATM Protocols...370 Transfer Modes... 370 STM...370 PTM... 371 ATM... 372 Connection-Oriented Mode...374 Fixed-Length Cells...376 Header Details...376 B-ISDN and ATM...378 AAL...378 ATM Layer... 381 Physical Layer...382 Activities... 384 ATM Implementation...386 VPs and VCs... 386 ATM in Action...388 ATM Communication...390 ATM Over SONET... 391 ix
Introduction to Wide Area Networks ATM LAN/WAN Solutions... 392 ATM Devices...392 Activities... 394 ATM Devices...395 Categories of ATM Devices...395 Routers... 396 CSU/DSUs...396 NICs... 397 Switches... 398 Intelligent Hubs...398 ATM Networks...399 Activities... 400 Extended Activity... 400 SMDS...401 SMDS Operation... 401 Switched...401 Multimegabit... 402 SNI...402 SMDS Protocols...403 SIP...404 DXI... 405 Router Functions... 406 DSU Functions...407 Advantages and Disadvantages...407 Activities... 409 Lesson 5 IEEE 802.16: The Wireless Last Mile...411 The Promise of Broadband Wireless Networks...412 802.16 Equipment... 413 The 802.16 Protocol Layers... 414 The CS... 414 The MAC CPS...415 The Privacy Sublayer... 419 The PHY... 420 802.16 Network Example... 420 Activities... 423 Lesson 6 Sample Network...425 Role of the Network in the Organization...425 Primary Applications Used by the Organization... 427 General Connectivity Strategy... 427 x
Contents Overall WAN/LAN Topologies... 427 Future Growth Plans and Migration Strategies...428 Activities... 429 Unit 7 Convergence of Communications Over WAN Technologies...439 Voice Over Alternative Technologies...448 History...448 Market Drivers...449 Voice Over the Internet... 450 VoFR... 452 Voice Over ATM... 454 Market Direction and Trends... 454 Activities... 456 Fundamental VoIP Network Components...457 Overview of the ITU-T H.323 Standard... 457 Version 1: Videophone... 458 Version 2: Packet-Based Multimedia... 458 Version 3: Under Development...458 Other Standards of the H.323 Family... 458 H.323 Network Components... 459 Terminals... 459 MCUs... 459 Gateways... 460 Gatekeepers... 460 MGCP... 461 MGCP Network Components... 462 MGCP Call Control Transactions... 464 Activities... 465 Factors Driving the Demand for Packet Telephony...467 Long-Term Trends...468 Open Standards, Open Market... 468 More Bandwidth...469 Carrier Applications... 469 Enterprise Applications...469 Voice Rides for Free...470 Transparent Technology...471 Improved Network Management... 471 Network Flexibility and Scalability...472 Access to New Applications... 472 Activities... 474 xi
Introduction to Wide Area Networks Private VPNs...476 Private Communications Networks... 477 Cost Savings... 479 Improved Efficiency... 481 Enhanced User Satisfaction...481 Activities... 483 Lesson 5 PSTN Remote Access...485 Remote Access Applications... 485 Dial-Up Access... 486 ISDN Access... 486 DSL Access... 488 Activities... 490 Course Quiz...501 Glossary...511 Index...543 WestNet s Related Titles...557 Notes...573 Overall Course Evaluation Survey...583 xii