PREFACE
xix
CHAPTER 1 INTRODUCTION TO COMMUNICATIONS, STANDARDS, AND PROTOCOLS
1.1 WHY STUDY COMMUNICATIONS
1
A Brief History 1
Applications 4
Issues 8
1.2 COMPUTER NETWORKS
9
Common Bus Topology 10
Star Topology 11
Ring Topology 12
Fully Connected Topology 13
Combined Topologies 13
1.3 STANDARDS AND STANDARDS ORGANIZATIONS
15
The Need for Standards 15
Standards Organizations 16
1.4 OPEn SYSTEMS AND THE OSI MODEL
18
Overview of the Model 22
Connection Strategies 24
Physical Layer 29
Data Link Layer 30
Network Layer 32
Transport Layer 33
Session Layer 36
Presentation Layer 38
Application Layer 40
Intemet Layers 42
Summary 42
1.5 THE FUTURE OF DATA COMMUNICATIONS
44
REVIEW QUESTIONS 51
EXERCISES 52
REFERENCES 53
CHAPTER 2 TRANSMISSION MEDIA AND CODES
2.1 INTRODUCTION
S4
2.2 CONDUCTIVE METAL
57
Twisted Pair 57
Coaxial Cable 59
2.3 OPTICAL FIBER
61
2.4 WIRELESS COMMUNICATIONS
66
Microwave Transmission 67
Satellite Transmission 70
Geosynchronous Satellites 71
Low Earth Orbit Satellites 77
Wireless LANs 81
Bluetooth 82
Free Space Optics 83
Summary 84
2.5 CODES
87
Early Codes 87
ASCII Code 89
EBCDIC Code 92
Unicode 92
2.6 SUMMARY
93
REVIEW QUESTIONS 94
EXERCISES 95
REFERENCES 96
CHAPTER 3 ANALOG AND DIGITAL SIGNALS
3.1 INTRODUCTION
97
3.2 DIGITAL ENCODING SCHEMES
98
NRZ Encoding 98
Manchester Encoding 100
3.3 ANALOG SIGNALS
101
Fourier''s Results 103
Applications of Fourier''s Results 106
3.4 BIT RATE
107
The Nyquist Theorem and Noiseless Channels 107
Noisy Channels 109
Shannon''s Result 110
3.5 DIGITAL-TO-ANALOG CONVERSION
112
Frequency Modulation 113
Amplitude Modulation 114
Phase Modulation 114
Quadrature Amplitude Modulation 115
3.6 ANALOG-TO-DIGITAL CONVERSION
118
Pulse Amplitude Modulation 119
Pulse Code Modulation 119
3.7 MODEMS
121
Signal Constellation 122
Modem Standards 125
Cable Modems 127
3.8 DSL
131
How It Works 132
Different DSL Technologies , 135
ADSL Lite G. Lite, ITU standard ITU G. 992.2
135
SDSL 136
HDSL and HDSL2 136
SHDSL 137
RADSL 137
IDSL 137
VDSL 137
3.9 SUMMARY
138
REVIEW QUESTIONS 139
EXEROSES 141
REFERENCES 143
CHAPTER 4 MAKING CONNECTIONS
144
4.1 INTRODUCTION
144
4.2 COMMUNICATION CARRIERS AND DEVICES
145
The Telephone System 145
Call Routing 147
Private Branch Exchanges 148
Cellular Phones 149
Fax Machines 151
4.3 TRANSMISSION MODES
153
Serial and Parallel Transmission 153
Asynchronous, Synchronous, and Isochronous Transmission 154
Simplex, Half-Duplex, and Full-Duplex Communications 158
4.4 INTERFACE STANDARDS
159
EIA-232 Interface 160
EIA-232 Subsets 162
Null Modems 163
X.21 Interface 164
USB 166
USB Connections 166
Data Transfer 168
USB Packets 170
FireWire 172
Connections 173
Communications 175
Arbitration 176
4.5 MULTIPLEXING
178
Frequency-Division Multiplexing 180
Time-Division Multiplexing 182
Statistical Multiplexers 183
Wave-Division Multiplexing 185
4.6 DIGITAL CARRIERS
186
Tl 186
SONET 188
Device Types 189
Payloads and Frames 191
4.7 CONTENTION PROTOCOLS
195
Aloha Protocols 196
Cartier Sense Multiple Access 199
Collision Detection 202
Collision Avoidance 205
Token Passing 205
Summary of Protocols 207
4.8 SUMMARY
207
RENEW QUESTIONS 210
EXERCISES 212
REFERENCES 214
CHAPTER 5 DATA COMPRESSION
215
5.1 INTRODUCTION
215
5.2 FREQUENCY-DEPENDENT CODES
217
Huffman Code 217
Arithmetic Compression 220
5.3 RUN-LENGTH ENCODING
225
Runs of the Same Bit 225
Runs with Different Characters 226
Facsimile Compression 226
5.4 RELATIVE ENCODING
229
5.5 LEMPEL~ZIV COMPRESSION
229
5.6 IMAGE COMPRESSION
235
Image Representation 235
JPEG Compression 238
DCT Phase 238
Encoding Phase 244
GIF Files 245
5.7 MULTIMEDIA COMPRESSION
246
MPEG 246
MP3 251
5.8 SUMMARY
254
REVIEW QUESTIONS 254
EXERCISES 255
REFERENCES 257
CHAPTER 6 DATA INTEGRITY
258
6.1 INTRODUCTION
258
6.2 SIMPLE ERROR DETECTION TECHNIQUES
259
Parity Checks 259
Analysis of Parity Checking 260
Checksums 261
6.3 CYCLIC REDUNDANCY CHECKS FOR ERROR DETECTION
261
Polynomial Division 262
How CRC Works 263
Analysis of CRC 265
CRC Implementation Using Circular Shifts 268
6.4 HAMMING CODES: ERROR CORRECTION
270
Single-Bit Error Correction 270
Multiple-Bit Error Correction 273
6.5 SUMMARY
274
RENEW QUESTIONS 275
EXERCISES 276
REFERENCES 277
CHAPTER7 DATA SECURITY
279
7.1 INTRODUCTION
279
7.2 ENCRYPTION ALGORITHMS
281
Caesar Cipher 282
Polyalphabetic Cipher 284
Transposition Cipher 284
Bit-Level Ciphering 285
Data Encryption Standards 287
DES 287
Triple DES 291
AES and the Rijndael Algorithm 292
Clipper Chip and the Skipjack Algorithm 296
7.3 KEY DISTRIBUTION AND PROTECTION
299
Shamir''s Method 300
Diffie-Hellman Key Exchange 300
7.4 PUBLIC KEY ENCRYPTION
302
RSA Algorithm 302
Digital Signatures 305
Authentication and Message Digests 308
Pretty Good Privacy 311
7.5 TRANSPORT LAYER SECURITY AND SERVER AUTHENTICATION
315
Transport Layer Security 316
X.509 Certificate 317
Handshakes 320
7.6 FIREWALLS
323
Packet Filtering 324
Application-Level Gateway 325
Stateful Inspection 327
7.7 VIRUSES
329
Infecting Files 330
Memory-Resident Viruses 332
Virus Evolution 333
Virus Sources 335
7.8 THREATS AND ATTACKS
336
The Intemet Worm 336
Computer Hackers 338
Other Threats 339
7.9 SUMMARY
341
RENEW QUESTIONS 345
EXERCISES 346
REFERENCES 348
CHAPTER 8 FLOW CONTROL
350
8.1 INTRODUCTION
350
8.2 SIGNALING
352
DTE-DCE Flow Control 353
X-ON/X-OFF 353
8.3 FRAME-ORIENTED CONTROL
354
Unrestricted Protocol 355
Stop-and-Wait Protocol 356
Protocol Efficiency 358
8.4 GO-BACK-n: A SLIDING WINDOW PROTOCOL
360
Frame Format 362
Features 363
Algorithm 366
8.5 SELECTIVE REPEAT: A SLIDING WINDOW PROTOCOL
370
Features 370
Algorithm 374
8.6 EFFICIENCY OF SLIDING WINDOW PROTOCOLS
377
8.7 PROTOCOL CORRECTNESS
380
Finite State Machines 380
STD for a Simplified Go-Back-n Protocol 381
State Transition Diagram for a Faulty Go-Back-n Protocol 383
Petri Nets 386
8.8 SUMMARY
390
RENEW QUESTIONS 392
EXERCISES 393
REFERENCES 395
CHAPTER 9 LOCAL AREA NETWORKS
396
9.1 INTRODUCTION
396
9.2 DATA LINK CONTROL
398
High-level Data Link Control Protocol 400
Frame Format 402
HDLC Example 405
Binary Synchronous Communications Protocol 408
9.3 ETHERNET: IEEE STANDARD 802.3
410
Concepts 411
Ethernet Frame Format 413
Physical Implementations of 10 Mbps Ethernet 415
9.4 FAST ETHERNET 100 MBPS
417
100BaseTX 418
100BaseFX 421
100BaseT4 422
Collision Domain 424
9.5 GIGABIT ETHERNET
424
MAC Sublayer 425
1000BaseX 427
1000BaseT 428
Beyond Gigabit Rates 430
9.6 TOKEN RING: IEEE STANDARD 802.5
433
Token and Frame Formats 434
Reserving and Claiming Tokens 436
Ring Maintenance 440
9.7 WIRELESS NETWORKS: IEEE STANDARD 802.11
443
Infrared and Radio Waves 444
Contention 447
Addressing 449
Frame Format 451
Wired Equivalent Privacy 453
Variations of 802.11 454
9.8 SUMMARY
455
REVIEW QUESTIONS 457
EXERCISES 459
REFERENCES 461
CHAPTER 10 CONNECTING NETWORKS
462
10.1 INTRODUCTION
462
10.2 LAYER 1 CONNECTIONS
465
Repeaters and Hubs 465
10.3 LAYER 2 CONNECTIONS
467
Bridges 467
Bridging Different Types of LANs 468
Routing 469
Routing Tables 469
Transparent Bridges 471
Route Learning 471
Frame Propagation 473
Spanning Tree Algorithm 475
Source-Routing Bridges 479
Switches and Switched Ethernet 480
Virtual LANs 484
10.4 LAYER 3 CONNECTIONS
487
Routing Tables 488
Centralized Routing 490
Distributed Routing 491
Static Routing 492
Adaptive Routing 492
10.5 DIJKSTRA''S ALGORITHM
493
10.6 THE BELLMAN-FORD ALGORITHM
496
Problems with the Bellman-Ford Algorithm
500
10.7 ADDITIONAL ROUTING METHODS
502
Link State Routing 502
Hierarchical Routing 503
Routing Information Protocol 506
Open Shortest Path First 509
Border Gateway Protocol 510
Summary of Routing Techniques 512
10.8 CONGESTION AND DEADLOCK
512
Congestion 512
Deadlock 515
10.9 SUMMARY
517
REVIEW QUESTIONS 519
EXERCISES 520
REFERENCES 523
CHAPTER 11 INTERNET PROTOCOLS AND APPLICATIONS
524
11.1 INTRODUCTION
524
11.2 INTERNET PROTOCOL
525
Overview of TCP/IP 526
Internet Addressing 528
Classless Addresses 531
Obtaining an Address 533
Domain Name System 534
IP Packets 537
Fragmentation 540
IP Routing 541
Routers 546
Multicast Routing 549
Resource Reservation Protocol 555
Internet Control Message Protocol 557
11.3 IPv6
559
IP Shortcomings 560
Packet Headers 561
IPSec 564
lPv6 Addressing 566
Compatibility with IPv4 569
Summary 570
11.4 TRANSPORT PROTOCOLS
571
Transmission Control Protocol 573
TCP Segment 574
Connection Management 577
Flow Control 580
Congestion Control 582
User Datagram Protocol 584
Real-Time Transfer Protocol 585
11.5 INTERNET APPLICATIONS
589
Virtual Terminal Protocols 589
Telnet 590
Secure Shell 593
File Transfers 596
FTP 597
Secure Copy 600
Simple Mail Transfer Protocol 600
Simple Network Management Protocol 604
Management Information Base 605
SNMP Commands 606
11.6 SUMMARY
608
REVIEW QUESTIONS 610
EXERCISES 612
REFERENCES 614
CHAPTER 12 INTERNET PROGRAMMING
616
12.1 INTRODUCTION
616
12.2 SOCKET PROGRAMMING
617
Sockets 618
Client/Server Model 619
Socket Data Structures 620
Socket Commands 621
Client/Server Example 621
Client Source Code 624
Server Source Code 631
12.3 WORLD WIDE WEB
633
Web Page Access 634
Hypertext Markup Language 636
Tags 637
HTML Forms 641
Client-Side Programming and JavaScript 644
12.4 COMMON GATEWAY INTERFACE AND SERVER-SIDE PROGRAMMING:
SETTING UP A SEARCH ENGINE
649
Forms 650
Query Strings 651
Example Search Engine 651
12.5 PERL PROGRAMMING: PIZZA ORDERING SYSTEM
654
Customer Interaction 655
Verifying Phone Numbers 658
Updating Customer Information 665
Placing an Order 668
Verifying the Order 669
12.6 SUMMARY
672
REVIEW QUESTIONS 673
EXERCISES 674
REFERENCES 676
CHAPTER 13 CIRCUIT TECHNOLOGIES
677
13.1 INTRODUCTION
677
13.2 INTEGRATED SERVICES DIGITAL NETWORK
678
Services 679
Architecture 681
Protocols 683
Signaling System 7 684
Basic Service Protocols 686
Call Setup 689
Broadband ISDN 691
13.3 VIRTUAL CIRCUIT PROTOCOLS: X.25 AND FRAME RELAY
692
Packet-Switched Network Modes 693
Virtual Circuits 693
Datagram Service 695
X.25 Interface Standard 696
Packet Format 697
Virtual Calls 698
Frame Relay 699
Frame Format 701
Committed Information Rate 702
Congestion Control 703
13.4 ASYNCHRONOUS TRANSFER MODE
705
Benefits of Small Fixed-Size Cells 706
Overview of ATM Network 708
Switching 709
Banyan Switches 710
Reference Model 712
Cell Definition 713
Header Error Control 714
Cell Loss Priority 716
Payload Type 716
Virtual Circuits and Paths 716
Connection Management 717
Connection Parameters 719
Adaptation Layers 720
AAL 1 721
AAL 2 723
AAL 5 724
Service-Specific Connection-Oriented Protocol 725
Gigabit Ethernet versus ATM 726
13.5 SUMMARY
727
RENEW QUESTIONS 727
EXERCISES 729
REFERENCES 730
GLOSSARY
ACRONYMS
INDEX