TABLE OF
CONTENTS

Chapter 1: INTRODUCTION 1

DATA COMMUNICATION 2

Components 3

NETWORKS 4

Distributed Processing 4

Network Criteria 4

Applications 6

PROTOCOLS AND STANDARDS 7

Protocols 7

Standards 8

STANDARDS ORGANIZATIONS 9

Standards Creation Committees 9

Forums 11

Regulatory Agencies 12

SUMMARY 13

PRACTICE SET 13

Multiple Choice 13

Exercises 15

Chapter 2: BASIC CONCEPTS 17

LINE CONFIGURATION 17

Point-to-Point 18

Multipoint 18

TOPOLOGY 18

Mesh 19

Star 21

Tree 21

Bus 22

Ring 23

Hybrid Topologies 24

TRANSMISSION MODE 24

Simplex 25

Half-Duplex 25

Full-Duplex 25

CATEGORIES OF NETWORKS 26

Local Area Network (LAN) 26

Metropolitan Area Network (MAN) 28

Wide Area Network (WAN) 28

INTERNETWORKS 29

SUMMARY 30

PRACTICE SET 30

Multiple Choice 30

Exercises 32

Chapter 3: THE OSI MODEL 35

THE MODEL 35

Layered Architecture 35

FUNCTIONS OF THE LAYERS 39

Physical Layer 39

Data Link Layer 40

Network Layer 41

Transport Layer 43

Session Layer 45

Presentation Layer 47

Application Layer 48

Summary of Layer Functions 49

SUMMARY 49

PRACTICE SET 50

Multiple Choice 50

Exercises 53

Chapter 4: SIGNALS 55

ANALOG AND DIGITAL 55

APERIODIC AND PERIODIC SIGNALS 57

Periodic Signals 57

Aperiodic Signals 58

ANALOG SIGNALS 59

Simple Analog Signals 59

Complex Signals 64

Frequency Spectrum and Bandwidth 65

DIGITAL SIGNALS 67

Amplitude, Period, and Phase 67

Decomposition of a Digital Signal 68

Medium Bandwidth and Significant Bandwidth 69

Medium Bandwidth and Data Rate: Channel Capacity 70

Use of Analog Signals to Transmit Digital Data 71

MATHEMATICAL APPROACH (OPTIONAL) 73

SUMMARY 74

PRACTICE SET 75

Multiple Choice 75

Exercises 77

Chapter 5: ENCODING 79

DIGITAL-TO-DIGITAL ENCODING 79

Unipolar 80

Polar 82

Bipolar 85

ANALOG-TO-DIGITAL ENCODING 90

Pulse Amplitude Modulation (PAM) 91

Pulse Code Modulation (PCM) 92

Sampling Rate 94

DIGITAL-TO-ANALOG ENCODING 95

Aspects of Digital-to-Analog Encoding 95

Amplitude Shift Keying (ASK) 96

Frequency Shift Keying (FSK) 99

Phase Shift Keying (PSK) 101

Quadrature Amplitude Modulation (QAM) 104

Bit/Baud Comparison 106

ANALOG-TO-ANALOG ENCODING 107

Amplitude Modulation (AM) 108

Frequency Modulation (FM) 110

Phase Modulation (PM) 112

SUMMARY 112

PRACTICE SET 114

Multiple Choice 114

Exercises 118

Chapter 6: TRANSMISSION OF DIGITAL DATA:
INTERFACES AND MODEMS 121

DIGITAL DATA TRANSMISSION 121

Parallel Transmission 122

Serial Transmission 123

DTE-DCE INTERFACE 125

Data Terminal Equipment (DTE) 126

Data Circuit-Terminating Equipment (DCE) 126

Standards 127

EIA-232 Interface 127

OTHER INTERFACE STANDARDS 134

EIA-449 134

EIA-530 138

X.21 139

MODEMS 140

Transmission Rate 142

Modem Standards 145

SUMMARY 152

PRACTICE SET 154

Multiple Choice 154

Exercises 160

Chapter 7: TRANSMISSION MEDIA 163

GUIDED MEDIA 164

Twisted-Pair Cable 164

Coaxial Cable 168

Optical Fiber 169

UNGUIDED MEDIA 176

Radio Frequency Allocation 176

Propagation of Radio Waves 176

Terrestrial Microwave 181

Satellite Communication 182

Cellular Telephony 184

PERFORMANCE 187

SUMMARY 188

PRACTICE SET 190

Multiple Choice 190

Exercises 195

Chapter 8: MULTIPLEXING 197

MANY TO ONE/ONE TO MANY 197

TYPES OF MULTIPLEXING 198

Frequency-Division Multiplexing (FDM) 199

Time-Division Multiplexing (TDM) 202

Inverse Multiplexing 209

MULTIPLEXING APPLICATION:
THE TELEPHONE SYSTEM 210

Common Carrier Services and Hierarchies 210

Analog Services 211

Digital Services 213

SUMMARY 219

PRACTICE SET 220

Multiple Choice 220

Exercises 223

Chapter 9: ERROR DETECTION AND CORRECTION 225

TYPES OF ERRORS 225

Single-Bit Error 226

Multiple-Bit Error 226

Burst Error 227

DETECTION 227

Redundancy 227

Vertical Redundancy Check (VRC) 228

Longitudinal Redundancy Check (LRC) 230

Cyclic Redundancy Check (CRC) 232

Checksum 235

ERROR CORRECTION 237

Single-Bit Error Correction 237

Hamming Code 238

Multiple-Bit Error Correction 241

SUMMARY 242

PRACTICE SET 243

Multiple Choice 243

Exercises 245

Chapter 10: DATA LINK CONTROL 247

LINE DISCIPLINE 248

ENQ/ACK 248

FLOW CONTROL 253

Stop-and-Wait 253

Sliding Window 255

ERROR CONTROL 258

Automatic Repeat Request (ARQ) 258

Stop-and-Wait ARQ 259

Sliding Window ARQ 261

SUMMARY 267

PRACTICE SET 268

Multiple Choice 268

Exercises 270

Chapter 11: DATA LINK PROTOCOLS 273

ASYNCHRONOUS PROTOCOLS 274

XMODEM 274

YMODEM 275

ZMODEM 275

BLAST 275

Kermit 275

SYNCHRONOUS PROTOCOLS 276

CHARACTER-ORIENTED PROTOCOLS 276

Binary Synchronous Communication (BSC) 277

BSC Frames 278

Data Transparency 281

BIT-ORIENTED PROTOCOLS 282

HDLC 284

Frames 286

More about Frames 291

Link Access Procedures 300

SUMMARY 300

PRACTICE SET 302

Multiple Choice 302

Exercises 304

Chapter 12: LOCAL AREA NETWORKS 307

PROJECT 802 307

IEEE 802.1 309

LLC 309

MAC 309

Protocol Data Unit (PDU) 309

ETHERNET 310

Access Method: CSMA/CD 311

Addressing 312

Electrical Specification 312

Frame Format 312

Implementation 314

TOKEN BUS 319

TOKEN RING 319

Access Method: Token Passing 319

Addressing 321

Electrical Specification 322

Frame Formats 322

Implementation 325

FDDI 327

Access Method: Token Passing 327

Addressing 330

Electrical Specification 330

Frame Format 332

Implementation: Physical Medium Dependent (PMD) Layer 333

COMPARISON 335

SUMMARY 335

PRACTICE SET 337

Multiple Choice 337

Exercises 341

Chapter 13: METROPOLITAN AREA NETWORKS 343

IEEE 802.6 343

Access Method: Dual Bus 343

Distributed Queues 346

Ring Configuration 348

Operation: DQDB Layers 349

Implementation 350

SMDS 351

Connection and Access 352

SUMMARY 353

PRACTICE SET 354

Multiple Choice 354

Exercises 355

Chapter 14: SWITCHING: A NETWORK L AYER FUNCTION 357

CIRCUIT SWITCHING 358

Space-Division Switches 359

Time-Division Switches 362

Space- and Time-Division Switching Combinations 364

PACKET SWITCHING 365

Datagram Approach 366

Virtual Circuit Approach 367

MESSAGE SWITCHING 369

NETWORK LAYER 370

Connection-Oriented and Connectionless Services 370

SUMMARY 371

PRACTICE SET 372

Multiple Choice 372

Exercises 374

Chapter 15: INTEGRATED SERVICES DIGITAL
NETWORK (ISDN) 375

SERVICES 375

Bearer Services 375

Teleservices 376

Supplementary Services 376

HISTORY 376

Voice Communication over Analog Networks 376

Voice and Data Communication over Analog Networks 377

Analog and Digital Services to Subscribers 377

Integrated Digital Network (IDN) 378

Integrated Services Digital Network (ISDN) 379

SUBSCRIBER ACCESS TO THE ISDN 380

B Channels 380

D Channels 380

H Channels 381

User Interfaces 381

Functional Grouping 383

Reference Points 385

THE ISDN LAYERS 385

Physical Layer 387

Data Link Layer 392

Network Layer 394

BROADBAND ISDN 398

Services 399

Physical Specifications 400

SUMMARY 401

PRACTICE SET 403

Multiple Choice 403

Exercises 407

Chapter 16: X.25 409

X.25 LAYERS 409

Physical Layer 410

Data Link Layer 410

Network Layer 410

PACKET LAYER PROTOCOL 411

Information Packets 411

Control Packets 413

Complete Packet Sequence 417

Virtual Channel ID Numbers 418

SUMMARY 419

PRACTICE SET 419

Multiple Choice 419

Exercises 421

Chapter 17: FRAME REL AY 423

FRAME RELAY LAYERS 424

Physical Layer 424

Data Link Layer 425

FRAME RELAY OPERATION 426

Relay 427

Switching 427

Congestion Control 429

IMPLEMENTATION 429

SUMMARY 430

PRACTICE SET 431

Multiple Choice 431

Exercises 432

Chapter 18: ATM 433

DESIGN GOALS 433

Packet Networks 434

Mixed Network Traffic 434

Cell Networks 435

Additional Advantages of ATM 439

ATM TOPOLOGY 440

ATM PROTOCOL ARCHITECTURE 442

Application Adaptation Layer (AAL) 442

ATM Layer 449

Physical Layer 453

SUMMARY 453

PRACTICE SET 454

Multiple Choice 454

Exercises 456

Chapter 19: SONET/SDH 459

SYNCHRONOUS TRANSPORT SIGNALS 460

PHYSICAL CONFIGURATION 461

SONET Devices 461

Sections, Lines, and Paths 462

SONET LAYERS 462

Photonic Layer 462

Section Layer 462

Line Layer 463

Path Layer 463

Device-Layer Relationships 463

THE SONET FRAME 463

Frame Format 464

Section Overhead 466

Line Overhead 466

Path Overhead 468

Virtual Tributaries 469

Types of VTs 469

MULTIPLEXING STS FRAMES 470

SUMMARY 471

PRACTICE SET 472

Multiple Choice 472

Exercises 475

Chapter 20: NETWORKING AND INTERNETWORKING
DEVICES 477

REPEATERS 478

Not an Amplifier 480

BRIDGES 480

Types of Bridges 482

ROUTERS 483

Routing Concepts 485

GATEWAYS 487

ROUTING ALGORITHMS 487

Distance Vector Routing 488

Link State Routing 495

SUMMARY 502

PRACTICE SET 503

Multiple Choice 503

Exercises 506

Chapter 21: TRANSPORT L AYER 507

DUTIES OF THE TRANSPORT LAYER 508

End-to-End Delivery 508

Addressing 509

Reliable Delivery 510

Flow Control 513

Multiplexing 514

CONNECTION 516

Connection Establishment 516

Connection Termination 517

THE OSI TRANSPORT PROTOCOL 517

Transport Classes 517

Transport Protocol Data Unit (TPDU) 518

Connection-Oriented and Connectionless Services 519

SUMMARY 520

PRACTICE SET 521

Multiple Choice 521

Exercises 523

Chapter 22: UPPER OSI L AYERS 525

SESSION LAYER 525

Session and Transport Interaction 526

Synchronization Points 527

Session Protocol Data Unit 528

PRESENTATION LAYER 529

Translation 529

Encryption/Decryption 531

Authentication 534

Data Compression 536

APPLICATION LAYER 538

Message Handling System (MHS) 538

File Transfer, Access, and Management (FTAM) 540

Virtual Terminal (VT) 541

Directory Services (DS) 542

Common Management Information Protocol (CMIP) 543

SUMMARY 545

PRACTICE SET 546

Multiple Choice 546

Exercises 548

Chapter 23: TCP/IP 549

OVERVIEW OF TCP/IP 549

TCP/IP and the Internet 549

TCP/IP and OSI 550

Encapsulation 550

NETWORK LAYER 551

Internetwork Protocol (IP) 551

Other Protocols in the Network Layer 556

TRANSPORT LAYER 558

User Datagram Protocol (UDP) 559

Transmission Control Protocol (TCP) 559

APPLICATION LAYER 562

Domain Name System (DNS) 563

TELNET 564

File Transfer Protocols 566

File Access Using NFS and RPC 568

Electronic Mail: SMTP 569

Simple Network Management Protocol (SNMP) 571

Gopher 573

Archie 573

Veronica 573

Wide Area Information Service (WAIS) 574

Hypertext Transfer Protocol (HTTP) 574

WORLD WIDE WEB (WWW) 574

Uniform Resource Locator (URL) 575

Browser Architecture 577

SUMMARY 581

PRACTICE SET 583

Multiple Choice 583

Exercises 590

Appendix A: ASCII AND EBCDIC CODES 593

Appendix B: NUMBERING SYSTEMS AND
TRANSFORMATION 595

Appendix C: REPRESENTATION OF BINARY NUMBERS 607

Appendix D: ONE╞S COMPLEMENT ARITHMETIC FOR
CHECKSUM CALCUL ATION 615

Appendix E: FOURIER ANALYSIS 619

Appendix F: HARDWARE EQUIPMENT FOR
ERROR DETECTION 623

Appendix G: HUFFMAN CODING 631

Appendix H: IP VERSION 6 639

ANSWERS TO SELECTED PROBLEMS 643

ACRONYMS 659

GLOSSARY 663

REFERENCES 691

INDEX 693



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