Answers to True/False Questions

Chapter 2. 1. F, 2. T, 3. F, 4. F, 5. T, 6. T, 7. T, 8. F, 9. T, 10. F, 11. F, 12. T, 13. T, 14. F, 15. F, 16. T, 17. F, 18. T, 19. T, 20. F, 21. F, 22. T, 23. F, 24. T, 25. F

Chapter 3. 1. F, 2. F, 3. T, 4. F, 5. F, 6. T, 7. F, 8. F, 9. F, 10. T, 11. T, 12. T, 13. F, 14. F, 15. T, 16. T, 17. F, 18. T, 19. T, 20. T, 21. F, 22. T, 23. F, 24. T, 25. T

Chapter 4. 1. T, 2. F, 3. F, 4. T, 5. F, 6. T, 7. T, 8. F, 9. T, 10. F, 11. T, 12. T, 13. F, 14. F, 15. T, 16. T, 17. F, 18. F, 19. T, 20. F, 21. F, 22. F, 23. T, 24. T, 25. F

Chapter 5. 1. T, 2. F, 3. T, 4. T, 5. T, 6. F, 7. T, 8. T, 9. F, 10. T, 11. T, 12. F, 13. F, 14. F, 15. F, 16. F, 17. T, 18. F, 19. T, 20. T, 21. T, 22. F, 23. F, 24. F, 25. T

Chapter 6. 1. T, 2. F, 3. F, 4. T, 5. T, 6. T, 7. F, 8. T, 9. T, 10. F, 11. F, 12. F, 13. T, 14. F, 15. F, 16. F, 17. T, 18. T, 19. T, 20. F, 21. F, 22. F, 2J.T, 24.F, 25.F

Chapter 7. 1. T, 2. T, 3. F, 4. T, 5. T, 6. T, 7. T, 8. T, 9. T, to. F, 11. T, 12. F, 13. T, 14. F, 15. F, 16. F, 17. T, 18. T, 19. F, 20. T, 21. T, 22. T, 23. F, 24. F, 25. F

Chapter 8. 1. T, 2. F, 3. T, 4. F, 5. T, 6. T, 7. T, 8. T, 9. T, to. T, 11. T, 12. T, 13. T, 14. F, 15. T, 16. T, 17. T, 18. T, 19. F, 20. T, 21. T, 22. T, 23. T, 24. F, 25. F

449

450 Answers to True/False Questions

Chapter 9. 1. T, 2. F, 3. F, 4. T, 5. T, 6. T, 7. F, 8. T, 9. T, 10. T, 11. T, 12. F, 13. F, 14. T, 15. F, 16. F, 17. T, 18. F, 19. T, 20. T, 21. F, 22. T, 23. T, 24. T, 25. T

Chapter 10. 1. F, 2. T, 3. F, 4. F, 5. T, 6. T, 7. T, 8. T, 9. F, 10. T, 11. F, 12. T, 13.T, 14.F, 15.T, 16.T, 17.T, 18.T, 19.T,20.F, 21.T,22.F, 23. F, 24. F, 25. F

Chapter 11. 1. T, 2. T, 3. T, 4. F, 5. T, 6. F, 7. F, 8. T, 9. F, 10. F, 11. T, 12. T, 13. T, 14. T, 15. F, 16. F, 17. T, 18. F, 19. F, 20. T, 21. F, 22. F, 23. T, 24. F, 25. F

Chapter 12. 1. T, 2. T, 3. F, 4. T, 5. T, 6. F, 7. F, 8. F, 9. F, 10. T, 11. F, 12. T, 13. T, 14. F, 15. F, 16. T, 17. F, 18. T, 19. F, 20. T, 21. F, 22. F, 23. T, 24. F, 25. F

\

Chapter 13 .. 1. T, 2. T, 3. T, 4. T, 5. F, 6. T, 7. T, 8. T, 9. F, 10. T, 11. T, 12. T, 13. F, 14. T, 15. T, 16. T, 17. F, 18. T, 19. T, 20. F, 21. F, 22. F, 23. T, 24. F, 25. F

Index

AlB switch, 232 Active network monitor, 401 ACU: see Dialers, automatic Adaptive equalizers

passband, 133-134 theory of operation, 130-133 use in modems, 69, 117, 118

Addressing extended, 332-333 HDLC ABM, 335-337 LAPB multilink, 338-339 SDLC convention, 187-188

ADD star concentrator CMST algorithm, 275 Aliasing, 50-52 Aloha random access, 391 Analog filters

classifications, 39-40 effect on periodic signals, 45 frequency response, 40 group delay, 45

Answer/originate convention, 113, 117, 119 Antialiasing filter, 52 Application layer protocol

functions, 324, 361 service elements, 361 terminal service classes, 362

ARPANET network description, 237-238 evolution to DON, 239 flow control, 296-297 IMP and TIP, 237 protocol, 296-297

Asynchronous balanced mode (ABM), 193, 334-337

Automatic answering, 124-125 Automatic gain control (AGC), 66-67

451

Backoff: see IEEE 802.3 protocol Balanced line driver and receiver, 146 Bernoulli trials, 307 Binary Synchronous Communications (BSC)

protocol character stuffing, 177 controller chip, 178 frame formats, 174-175 operation, 175-177 polling and selecting, 176 transparent mode, 177

Binomial distribution, 307-308 BISYNC: see Binary Synchronous Communi-

cations (BSC) protocol Bit stuffing, 186-187 BORSCHT: see Voice-grade channel Branch-exchange network design algorithm,

298-300 Bridge, 389 Bridged tap, 99 Broadband LAN, 390, 402, 411, 413 Buffer delay queueing model, 200-202 Butterworth filter, 43-44

Cambridge Ring LAN, 410-411 CBC DES operation, 431 Central limit theorem, 309 CFB DES operation, 432 Character stuffing, 177 Ciphertext, 427 Cluster controller, 217 Cohesion, 258, 286 Communications processor

front-end (FEP), 226-227 historical roles, 226-228 interface and gateway nodes, 229

452

Communications processor (cont.)

PAD, 229 remote concentrator, 228 uses in networks, 230-234

Compression ratio, 219 Conditioning, 99 Congestion, 288-289 Connectivity

definition, 258 degree of graph, 258 k-connectivity test, 259 node- and link-disjoint paths, 259

Constrained minimal spanning tree (CMST) network

ADD algorithm, 274-276 with concentrators, 272-274 design problem formulation, 267-268 Esau-Williams algorithm, 270-272 heuristic approach, 268 Kruskal algorithm, 268-270 NEWCLUST algorithm, 277

Contention ring LAN access, 410 Crypto key codes

changing, 429 definition, 428 distribution issues, 429 key control center (KCC), 429 key length, 429-430

CSMA/CD: see Random LAN access Cut-saturation network design method, 300-

301 Cyclic redundancy check

basic theory, 199-200 coder/decoder circuit, 200-201 generating polynomial, 200 relation to FCS, 200

Data access arrangement (DAA), 124-125 Data communications, 8-9 Data Encryption Standard (DES)

algorithm, 430 development, 429-430 implementation, 433 modes of operation, 431-433

Datagram basic concept, 340, 350 in DNA, 363 old X.25 formats, 350-352 use in operational networks, 352

Data link protocol balanced operation, 334-337 classification, 172-173 comparisons. 195

Data link protocol (cont.)

functions, ITI-172 synchronous, 173

Data link protocol layers frame header and trailer, 330

Index

HDLC: see High-Level Data Link Control (HDLC) protocol

operation through networks, 330-331 Data networks

backbone subnetwork, 233 component interconnections, 230-233 definition, 8 evolution, 207-208, 234-235 local access subnetwork, 234, 249 operational examples, 234-242 topologies, 10-11,230-233 VAN: see Value-added network (VAN) WAN: see Wide area network (WAN)

DATAPAC network, 241-242 Data set: see Modem D-bit in X.25, 346 DDS system

Channel Service Unit (CSU), 84 Data Service Unit (DSU), 84 evolution, 80 multiplex hierarchy, 85

Deadlock, 288 DECNET: see Digital Network Architecture

(DNA) Defense Data Network (DON), 238-239 Degree of a graph, 258 Delay, 280-282 Dialers, automatic

classification, 127 parallel port (RS-366) operation, 127-129 sequence of operations, 126-127 serial port operation, 129-130

Dial-up (public) telephone line, 74, 98-102 Digital Data Communications Message Proto-

col (DDCMP) acknowledgments, 182-183 byte count transparency, 181 controller chip, 196 frame format, 181-183 operation, 183-185 polling and selecting, 182, 185

Digital Data Exchange (DDX) network, 242 Digital filters

classification, 57 design example, 56 impulse response,57 transversal, 58-60 using FFT. 57

Index

Digital Network Architecture (DNA) Ethernet option, 363-364 historical development, 363 layers and functions, 364 protocol formats, 365 routing, 364

Digital voice DM and CVSD, 440-441 DPCM and ADPCM, 440-442 LPC vocoder, 442---443 PCM, 80-82, 440

Dijkstra shortest-path algorithm, 291 Discount Dog Mega-Stores, 245-246 DTEIDCE interface: see Physical interface Duobinary modulation, 403

ECB DES operation, 431 Echo canceling, 93 Echo suppressors, disabling, 143 Encryption, 427-429: see also Data Encryption

Standard (DES) Equalization

adaptive or automatic: see Adaptive equalizers

compromise, 64, 130 general use of, 48

Error checking correction, 197, 199 CRC and FCS: see Cyclic Redundancy

Check LRC, 198 parity, 198

Esau-Williams CMST algorithm, 270-271 Ethernet, 390, 393; see also IEEE 802.3

protocol Exponential distributions, 311, 312

Fast Fourier transform (FFT), 54, 56 Fast select, 180, 345 Fiber optic links: see Lightguide links Flag byte, 186, 332 Flooding, 293 Flow control

buffer allocation, 294-296 with data link protocol, 294 direction, 13-14 in operational networks, 296-297 sliding windows, 294-295, 349-350, 355-

357 XON/XOFF, 220, 294

Flow in networks graph models, 266-267 max-flow min-cut theorem, 285-287

453

Flow in networks (cant.) maximum flow between terminal pairs, 287 multicommodity maximal flow, 287 multiterminal maximal flow, 287 optimal formulation, 284

Fourier series, 26, 29, 31 Fourier transform, 34, 36-38, 54 Fragmentation, 373 Frame

T-carrier, 82, 86-87 TDMPX, 212-215 STMPX, 219, 221

Frame check sequence (FCS), 188, 200, 395 Frequency-division multiplexing (FDM), 75-

76,210-211 FSK modems, 64-65, 111-114 Futures forecasting, 437

Gateway node fragmentation, 373 functions, 373 for LANs, 389

Gaussian (normal) distribution, 309 Geometric distribution, 308, 313

Handshaking with automatic dialing, 156-162 digital interface, 341 modem DTE/DCE interfaces, 155-163 point-to-point, 156-161 polled, 161-163

Haywire connectors, 164-165 Heuristic network design

comprehensive algorithms, 298-301 motivation for, 248 tree CMST algorithms, 268-279

High-Level Data Link Control (HDLC) protocol

ARM and ABM, 334 evolution from SDLC, 193-194,332 extended sequence numbers, 332 frame formats, 332-335 operational example, 335-337 relation to X.25 LAP and LAPB, 332

Hybrid with FDX modems, 113 function, 77 with SLIC, 101

IEEE 802 protocol development. 390 LLC. 406-407

454

IEEE 802.3 protocol (CSMAfCD) address fields, 394-395 backoff, 393-394 frame format and types, 393-395 frame length, 395 jam, 394

IEEE 802.4 protocol (token bus) alternate versions, 402-403 error flags, 403 frame formats, 403-404 jabber control, 403

IEEE 802.5 protocol (token ring) delimiter coding, 399 error recovery with double ring, 397-398 evolution, 399 frame formats, 400 monitor station, 401-402 priority procedure, 400

Independence assumption, 281 Integer programming, 265-267 Integrated networks, 438-439 Integrated Services Digital Network (ISDN),

9, 103, 329-330, 438, 443-444 INTELSA T, 89-90 Interarrival time, 310, 312 Internet Datagram Protocol (IDP), 407-408 Internetwork protocol

Internet Protocol (lP), 376-377 X.75, 374-375

Intersymbol interference (lSI) definition, 47 effects on transmission, 46 mitigation of, 47 see also Nyquist shaping

Impulse function definition, 35-36 Fourier transform of, 37 digital, 57

Impulse train, 49-50 Information Systems Network (lSN), 415-416

Key: see Crypto key codes Keying, 64 Kleitman k-connectivity test, 259 Kolmogorov probability model, 302-304 Kruskal CMST algorithm. 269

LAP and LAPB protocol, 332, 337 LAPD protocol. 444 Leased (pri vate) telephone line

bridging, 99 conditioning, 99 characteristics, 98-102

Lightguide links background, 94 FT3 system, 96 repeater spacing, 97

Limited distance modem (LDM), 122 Linear programming

basic feasible solution, 263 canonical form, 262 cost function, 260 dual program, 264-265, 286-287 program formulation, 261-266 standard form, 264

Line sharing unit, 217 Link capacity

queueing model formulation, 282 optimal assignment, 283

Link-disjoint paths, 259 Little's formula, 314 Loading coils, 99 Local area network (LAN)

Index

access methods: see IEEE 802.3-802.5 protocol

classification, 390 components, 388-389 definition, 388 standard: see IEEE 802 protocol

Logical channel, 341 Logical link, 363 Loopback testing

BER tests, 167 with modems, 165-166 with multiplexers, 216

LV 6.2,372

Manchester coding conventional, 392-393 differential, 399 signal spectrum, 393

Manufacturing automation protocol (MAP), 408-409

Markov property, 311 Max-flow min-cut theorem, 285 Minimal spanning tree (MST)

definition, 257 Prim algorithm, 257 see also Constrained minimal spanning tree

(CMST) networks Mixed integer programming, 267 Modem

basic classifications, 110-111 comparison table, 121 general function. 16 line connection, 122-123

Index

Modem (cant.)

simple DTEIDCE interface, 110 standards, III

Modem connections with DAA, 123-126 for dial back-up, 125 to dial-up lines, 122-126 direct connect, 123 FCC registration, 122-123

Modem pool, 217 Modem-sharing units. 216-217 Modulation, analog

basic concepts, 6G--61 double-sideband, 62 frequency, 63

Modulation, digital classification, 63 FSK,64-65 PSK and DPSK, 65-66 QASK and QAM, 66-69 in satellites, 92

Multilink protocol, 337-339, 367 Multiplexers

asynchronous, 211 basic functions, 16, 209-210 frequency-division. 21G--211 interfaces, 209-210 statistical: see Statistical multiplexers time-division: see Time-division multiplex-

ing (TDM) Multiplexing, in telephone system: see Tele­

phone network

Network: see Data networks; see also Tele-phone network

Network component classification, 16-17 Network control system, 167 Network graphs

adjacency matrix, 252 cut-set, 253, 256 definitions, 25G--252 incidence matrix, 253-255 tree, 253, 254-255 see also Minimal spanning tree (MST)

Network modeling, 248-249 Network protocol layer

connected and connectionless, 323. 340 X.21 operation, 341

Network security: see Security NEWCLUST concentrator CMST algorithm,

277-278 Node-disjoint paths, 259 Null modem. 164-165 Nyquist signal shaping. 47-48

OFB DES operation, 432-433 Optical transmission

modal dispersion, 94-95 single mode, 95 sources and detectors, 95-96

Optimal network design comprehensive approaches, 246, 298 defining optimality, 247 design constraints, 298 design criteria, 246, 298

OSI Reference Model, 322-325

Packet assembly and disassembly (PAD) communications processor roles, 229 general functions. 377-378 PAD operation, 38G--382 parameters and profiles. 379 X.3/X.28/X.29 standards, 378-379

PBX as LAN, 411-412 Permissive setting, 124 Phase coherent FSK, 402-403 Phase continuous FSK, 402 Physical interface

automatic dialers, 126-130 basic functions, 137-139, 323 current loop, 139 digital X.21, 327-329 EIA RS-232C and V.24: see RS-232C EIA RS-449 and V.24rev: see RS-449 serial I/O ports, 149-155

Plaintext, 427 Poisson distribution, 309. 312 Polling and selecting

broadcast select, 180

455

data link procedures, 173-174, 180, 185, 188, 194

fast select, 180 modem operation, 161-163

Port selection basic functions, 217-218 port class, 217

Presentation layer protocol basic functions, 324, 359-360 syntax, 360 videotext. 360

Prim MST algorithm, 257 Private line: see Leased telephone line Probability "mass", 303-304 Probability theory, 302-305 Protocol

asynchronous. 15-16. ISO controller chips. 178. 179 see also Data link protocol

456

Protocol layers functional relationships, 325 network dependent and independent, 352 OS! Reference Model, 323-324 simplified example, 320--321 transport subnetwork, 321, 357

PSK modems carrier recovery, 116 DPSK, 116 FDX two-wire, 17-120 general theory, 65-67, 115-117 HDX,II6-117

Public key crypto, 433-434

QAM modems, 66, 118 QASK modems

AGC,119 FDX with echo cancelling, 118 FDX two-wire, 119 general theory, 66-69, 118-120 HDX,118 split-stream capability, 118

Q-bit in X.25 PAD operation, 379-382 Queueing system

components, 311 equilibrium model, 312-314 Kendall notation, 312 M/M/I queue, 312 traffic intensity, 313

Radio AM broadcast receiver, 62-63 Data Under Voice (DUV), 89 digital PSK, 89 future prospects, 97 telephone microwave, 88-89

Random LAN access CSMA and CSMA/CD, 391-392 Ethernet: see IEEE 802.3 protocol multiple access, 391 p-persistent CSMA, 392

Random variables covariance, 307 cumulative distribution function, 306 definition, 305 expected (mean) value, 306 independence, 307 probability density function, 305 variance and standard deviation, 306

Reconstruction filter, 52 Registcr insertion LAN access, 411 Regulation. FCC, 20

RS-232C circuit functions, 141-143 for OS! physical layer, 326 relation to V.24 and V.28, 139, 142 signal characteristics, 140--141 simple FDX operation, 144 specific examples: see Handshaking

RS-366 and V.25, 127-129 RS-422 and V.II, 145-149 RS-423 and V.IO, 145-149 RS-449

Index

capabilities beyond RS-232C, 145-146 circuit characteristics, 145-149 circuit functions, 147-149 for OSI physical layer, 326 relation to V.35, 149

Rotary, 217-218 Routing

classification of methods, 288-290 Dijkstra algorithm, 291-291 distance criteria, 290 directory, 292-293 flow-deviation method, 294 shortest route formulation, 290--291 techniques, 293

Sample space, 302 Sampling theorem, baseband, 52 Satellite access, 91-92 Satellite Business Systems (SBS) network, 93

94 Satellite links

carrier frequency, 90--91 echo cancellation, 93 FDM/FM/FDMA,91 geosynchronous orbit, 89 TDMIPSKlTDMA, 92 transmission delay, 90

Scramblers in modems, 69, 115, 1l7, 119 self-synchronous, 135 structure and operation, 134

Secondary modem channels, 112, 167 Security

attacks, 421 fundamental considerations, 419-422, 426 personnel management, 425 spoofing, 421 techniques, 424-426 telephone system vulnerability, 421-423

Selecting: see Polling and selecting

Index

Sequence numbers data link protocol, 180, 182-183, 188 extended, 188, 332 multilink, 338 TPDU, 354

Session layer protocol functions, 324, 358 session protocol data units (SPDU), 359 subsets, 358-359

Signaling, telephone common channel (CCIS), 77 E and M, 77 on local loops, 101 tone (SF, MF, 2VF, DTMF), 77-78

Signals, electrical, 24-27 SIT A network, 235-237 Slotted-ring LAN access, 410 Spectral density, 35, 38-39 Spectrum

continuous, 34-39 line, 27, 33 magnitude and phase, 29-30 modem, 112, 114, 119, 120 of periodic analog signals, 26-34 table of relationships, 55 two-sided, 32-33

Split-phase: see Manchester coding Split-stream modem, 118, 216-217 Spoofing, 421 Square wave, 26-34 Standards

de facto, 20 for modems, III for networks, 322-325 organizations (CCITT, ISO, EIA, IEEE,

NBS, ANSI), 18-19 OSI Reference Model, 322-325

Station, 388 Statistical multiplexers

aggregate and composite rates, 219 buffer delay, 220 dynamic bandwidth allocation, 218-219 flow control, 220 frame structure, 219,221 polling, 222-223 principles of operation, 218-219 specifications and features, 221-225 switching, 223-224

Switches control, 78 crossbar, 78 for data, 11-13

Switches (cont,)

electronic (ESS), 79 packet, 228-229 space- and time-division, 78-79 step-by-step, 78 store-and-forward, 228

Synchronous Data Link Control (SDLC) protocol

acknowledgments, 188 controller chips, 178, 196 flag byte, 186 flow control frames, 180-190 frame formats, 187-188, 189, 190-192 modes, 190, 192-194 loop mode, 193 operation, 190-191, 193-194 P/F bit, 188 transparency by bit stuffing, 186-187

Systems Network Architecture (SNA) binding, 371 chaining and bracketing, 371-372 flow control, 370, 371 historical development, 366-367 layer functions, 369-372 terminology, 367-369

Taps: see Security TELENET network

description, 239-241 III PAD, 240 routing and flow control, 297 X,25 protocol, 240-241

457

Telephone channel: see Voice-grade channel Telephone network

analog FDM carrier system, 75-78 channel group, 76 clear channel coding, 86 digital TDM carrier system, 79-87 D-channel bank, 80-82 digroup, 80 exchange plant, 74 ISDN transition, 443-445 LATA,74 PCM voice encoding, 80-82 supergroup, mastergroup, jumbogroup, 76 T-carrier, 80-84, 86-87

Tests: see Loopback testing Time-compression multiplexing (TCM), 86,

444 Time-division multiplexing (TDM)

basic concepts, 212-213 bit and character interleaving, 212-214 clocking, 214, 216

458

Time-division multiplexing (cont.)

frame format, 214 frame synchronization, 212-213, 214-215 interfaces, 215 with split-stream modems, 216, 217

Token LAN access, 396-397, 405 TRANSPAC network, 242 Transport layer protocol

operational example, 355-357 quality of service, 323, 352-353 service classes, 354 TPDU formats and types, 355-356

Transport protocol data unit (TPDU), 355-356 Transport subnetwork, 321, 357 TYMNET network, 241, 297

UART asynchronous data format, 150 commercial examples, 153-154 error flags, 151 idle patterns, 150 modem controls, 155 parity checking, lSI relation to USART, 150 use in serial 1/0 ports, 138, 149

Uniform sampling theorem, 52 Utilization factor, 313

Value-added network (VAN), 226, 234-242 Videotext, 360 Virtual circuit, 321, 340, 367 Virtual route, 367 Virtual terminal protocol

in application layer, 361 ARPANET Telnet, 361 in DNA, 366

Vocoder,442-443 Voice-grade channel

BORSCHT on local loop, 101-102 conditioning, 99 distortion, 102-103 frequency response, 98-99 nominal bandwidth, 98 ringing, 101 tip and ring, 78 two-wire and four-wire, 77

Index

see also Leased (private) telephone line, and Dial-up (public) telephone line

Wangnet LAN, 413-414 Weighted graph, 256 Wide area network (WAN), 208, 233-234 Wideband modems, 120 Window flow control

basic technique, 294-295 in data link protocol, 189-190,332 size negotiation, 349-350 in SNA, 370 TPDU credit, 354 X.25 protocol layers, 346-347, 350

Wiring concentrator, 397-398

X.21 physical interface, 327-329 X.25 network layer protocol

old datagram operation, 350--352 facilities, 343, 345, 349-350 flow control, 346-350 normal operation, 342 operational example, 349 packet types and formats, 343-348

XLAN,414 XON/XOFF flow control, 220, 294