Symbols - ptgmedia.pearsoncmg.comptgmedia.pearsoncmg.com › images › 1578702275 › index › 1578702275index.pdfCisco MCS-7822, 389 Cisco MCS-7835, 390 Cisco VG200 VoIP gateway,

I N D E X

Symbolsµ-law, 59

Numerics10-high-day (10HD) busy period, 4161750 series routers, 912600 series routers, 92–94

configuring, 147–148digital T1/E1 packet voice trunk, 103–104PVDM, 103VICs, 102voice/fax network module, 101–102

3600 series routers, 95Cisco 3620 modular access routers, 95Cisco 3640 modular access routers, 95Cisco 3660 modular access routers, 95configuring, 148, 150–151digital T1/E1 packet voice trunk, 103–104hardware, verifying installation, 156PVDM, 103VICs, 102

port addressing, 155selecting, 154–155

VNMsassembly, 155selecting, 152

voice/fax network module, 101–1027200 series routers, 112–1147500 series routers, 114, 117

AA bit, 73ABBH (average bounding busy hour), 416ABCD bit pattern, 74

robbed bit format, 76trunk configuration, 237–239

ABR (available bit rate), 308access codes, 124access gateways, 375

access layer, 9in new-world networks, 18

access numbers, pilot number, 374access servers, AS5300, 107

DSP module, 170DSP module, selecting, 172feature card module, 170feature cards, selecting, 171–172MICA (modem ISDN channel

aggregation), 170setting up, 168

ACD, 421–422adaptive differential pulse code modulation

(ADPCM), 431adding string description to voice ports, 185address signaling, 36, 417Ad-Hoc conferences, 391adjunct control PBXs, 406adjusting

voice port timing parameters, 212–213voice quality, 203

admission control, 349CCM, 381–383

ADPCM (adaptive differential pulse code modulation), 431

advanced router systems (ARSs), Cisco 7500 series,114, 117

A-law, 59alert signaling, 418alerting indicators, 38allocation of bandwidth in voice networks, 381–383analog signaling

coding, 61delay-start, 35digitization

compression, 61–64encoding process, 60–61quantization process, 58–60sampling, 56–57

immediate-start, 36supervisory, 28wink-start, 34–35

analog technologiesaccess gateways, 375E&M signaling

496

Type I lines, 42–43Type II lines, 43Type III lines, 44Type IV lines, 44Type V lines, 46

hybrid 2-to 4-wire conversion, balanced, 49telephones

dialer, 27glare, 30handset, 26hybrid 2- to 4-wire converter, 27placing a call, 23–26power supply, 40ringer, 27sidetone, 27switch hook, 27

trunks, 46–47CO trunks, 47DID/DOD trunks, 48FXO trunks, 47–48FXS, 48private trunk lines, 47telco trunks, 48

voice-grade channels, bandwidth, 56voice networks, 6

cable connections, configuring on MC3810, 166–167

echo, 49–50voice ports, configuring, 182–183

applicationsFXS, 129gatekeepers, 133–134IP Phone, 130MCM (Multimedia Conference Manager),

133–134, 139applying QoS policies to VoFR, 264–265architecture

ATM, requirements of, 308DVMs (digital voice modules), 160–161ISDN, 81PBXs, 408, 410–414

line interfaces, 412main system controller, 410trunk interfaces, 413wiring, 413–414

Architecture for Voice, Video and Integrated Data. See AVVID

ARS (advanced router systems), Cisco 7500 series, 114, 117

AS5300sDSP module, selecting, 172feature cards, selecting, 170–172MICA (modem ISDN channel aggregation),

170setting up, 168

assembling VNM/VIC for 3600 routers, 155assigning DLCIs to Frame Relay subinterfaces,

270–271ATM (Asynchronous Transfer Mode)

architectural requirements, 308bandwidth, calculating, 312configuration commands

dial-peer voice voatm, 324encapsulation, 320inarp parameter, 325interface atm, 319mode, 316, 318–319pvc name, 319session target, 324vbr-rt, 322

MC3810 fixed prioritization, 314–316MFT (Multiflex Trunk), 311PVCs, virtual template parameters, 321SAR, 309service classes, 308–309

minimizing delay, 310non-real time, 314, 316real time, 314–315

traffic shaping, 312for data/video, 314

atm pvc command, 326auditing network inventory, 428–429

global firms, 440multinational firms, 463pan-European firms, 449

auto-cut-through command, 191–192automated attendant, 421available bit rate (ABR), 308availability on old-world telephony systems, 390average bounding busy hour (ABBH), 416average options for voice traffic, calculating,

323–324

analog technologies

497

AVVID (Architecture for Voice, Video and Integrated Data), 14–16

access gateways, 375components of, 372

access gateways, 375CallManager, 373Cisco IP Phones, 375uOne, 374

hardwareCisco conference bridges, 391–392Cisco WebAttendant, 392gateways, 386–387, 389IP Phone, 384–385media convergence servers, 389–390

IP protocolsDHCP, 376H.323, 377MGCP, 378–379SCCP, 379TFTP, 376

signaling, 380

BB8ZS (Bipolar with Eight-Zero Substitution Return-

to-Zero), 77backplane (PBXs), 411balanced hybrid 2- to 4-wire conversion, 49bandwidth

allocating, 309, 381–383ATM, calculating, 312calculating for voice calls, 359–360conservation techniques, digital speech

interpolation, 65managing, 349reserving, 344

on DLCIs, 275voice-grade analog channels, 56

baselining input/output power levels, 205BC (Basic Call) sublayer, QSIG, 419Bc (committed burst size), configuring, 281Be (excess burst), configuring, 281BECN (backward explicit congestion notification),

260BHCA (busy hour call attempts), 416Bipolar Alternate Mark Inversion Return-to-Zero, 77

bipolar violation (BPV), 77Bipolar with Eight-Zero Substitution Return-to-zero

(B8ZS), 77BPV (bipolar violation), 77break segment, 36building blocks of IP voice installations

backbone speed and scale, 349bandwidth management/admission control, 349congestion management, 350packet classification, 349queue management, 350

burst options for voice traffic, calculating, 323–324business level telephone voice quality, 66busy hour call attempts (BHCA), 416busy hour call handling, PBXs, 415–416busy signal, 38BVM (BRI voice module)

configuring on MC3810, 163–164specifying as clock source, 164

Ccabinet carriers, PBX systems, 411–412cabinet/shelf controller, PBX systems, 409cablelength long command, 216cablelength short command, 216cabling

analog voice connections (MC3810), 166–167PBX systems, 413–414

calculatingaverage options for voice traffic, 323–324bandwidth

ATM, 312for voice calls, 359–360

burst options for voice traffic, 323–324busy-hour call handling, 416centum call seconds, 416decibel levels, 205delay budget, 435, 437–438erlangs, 416fragmentation size, 268–269payback period of capital investments, 460–461peak options for voice traffic, 323–324

call detail recording (CDR), 421call legs, 181

call legs

498

call progress indicators, 38call progress tone, voice port configuration, 185call setup (VoFR), displaying information, 301–302CallManager, 373

admission control, 381–383callout, PBX systems, 416–417calls

analog, placing, 23–26VoIP, 345

capacitors, 27capacity planning

for voice traffic, 416–417integrated voice/data networks, 438–439

global firms, 445multinational firms, 468–470pan-European firms, 453, 456–458

capital investments, calculating payback period, 460–461

carriers (PBX systems), 411–412CAS (channel-associated signaling), 79, 317, 417case studies, network design, 440

global firms, 440–448multinational firms, 462–471pan-European firms, 449–461

Catalyst 6000 Voice T1 module, 388CBR (constant bit rate), 308CBWFQ (class-based weighed fair queuing),

354–355ccfrf11 function calls, displaying, 297, 299CCM (Cisco CallManager), admission control,

381–383CCS (common channel signaling), 80, 317, 418–419ccs connect command, 217ccswvoice function calls, displaying, 299–300CDR (call detail recording), 421cells (ATM), SAR, 309CELP (code excited linear predictive) coding, 63centralized control PBXs, 403centum call seconds, 416channel banks, drop-and-insert, 12characteristics

of access layer, 9of distribution layer, 10

Chord, 60CIPT (Cisco IP Telephony Solutions), 373CIR (committed information rate), 260

configuring on PVC/SVC, 280

circuits, local loop, 28–32, 39circuit-switching, 13, 414Cisco 1750 series routers, 91Cisco 2600 series routers, 92–94

configuring, 147–148digital T1/E1 packet voice trunk, 103–104PVDM (Packet Voice DSP Module), 103VICs, 102voice/fax network module, 101–102

Cisco 3600 series routers, 95Cisco 3620 modular access routers, 95Cisco 3640 modular access routers, 95Cisco 3660 modular access routers, 95configuring, 148, 150–151digital T1/E1 packet voice trunk, 103–104hardware, verifying installation, 156PVDM (Packet Voice DSP Module), 103VICs, 102

assembly, 155port addressing, 155selecting, 154–155

VNMsassembly, 155selecting, 152

voice/fax network module, 101–102Cisco 7200 series routers, 112–114Cisco 7500 series routers, 114, 117Cisco AS5300 routers, 107

feature cards, selecting, 171–172Cisco AS5800 routers, 110–112Cisco conference bridges, AVVID, 391–392Cisco IP Phones, 375. See also IP Phones

model 7910, 384model 7960, 385

Cisco MC3810 router, 105–107Cisco MCM (Multimedia Conference Manager), ,

107, 133–134, 139Cisco MCS-7822, 389Cisco MCS-7835, 390Cisco VG200 VoIP gateway, 387–388

call progress indicators

499

Cisco voice-over routersconnection types

local, 123off-net, 124on-net, 123on-to off-net, 126PLAR, 124tie-line, 125

trunk calls, configuring, 286–287Cisco WebAttendant for AVVID, 392Cisco Works Voice Manager, 134Cisco’s VoFR implementation, 262–264Cisco’s VoIP implementation, 347class command, 271classes of service (ATM), 308–309

minimizing delay, 310classification schemes (packets), 349CLECs (competitive local exchange carriers), 7client/server-based PBXs, 407–408clock source command, 215clocking, T1 connections, 76–77clustering technology, Cisco CallManager, 390CO (central office), 6

local loop, 28–32switches, 40–41trunks, 47

codec command, 192codec complexity command, 240codecs (coder-decoders), 56

compression types, 193–194coding, 61, 431coloring, 265combining voice and data traffic, 16–18, 131comfort noise, 65commands

atm pvc, 326auto-cut-through, 191–192cablelength long, 216ccs connect, 217class, 271clock source, 215codec, 192codec complexity, 240compand-type, 195connection, 197connection tie-line, 201connection trunk, 202–203

controller, 215cptone, 185debug, 248, 331, 363debug ccfrf11 session, 297, 299debug ccswvoice vofr-debug, 299debug ccswvoice vofr-session, 299debug frame-relay fragment, 300–301debug voice vofr, 301–302description, 185, 216destination-pattern, 224, 230dial-peer voice, 224, 229–230dial-peer voice voatm, 324dial-type, 187ds0-group timeslots type, 218–220echo cancel coverage, 209echo-cancel enable, 208encapsulation, 320encapsulation frame-relay, 270forward digits, 228frame-relay adaptive-shaping, 281frame-relay bc, 281frame-relay be, 281frame-relay cir, 280frame-relay fair-queue, 278–279frame-relay fragment, 279–280frame-relay interface dlci, 270–271frame-relay mincir, 280frame-relay traffic-shaping, 274frame-relay voice bandwidth, 275framing, 216impedence, 208, 211input gain, 206, 215interface atm, 319linecode, 216–217loopback, 234loop-timed, 216loss plan, 206loss-plan, 210map-class frame-relay, 275mode, 316, 318–319mode cas, 317mode ccs, 218network-clock-select, 164non-linear, 209num-exp, 226operation, 189output attenuation, 206, 215

commands

500

port, 225–226prefix, 228pvc name, 319ring frequency, 187ring number, 186session target, 231–234, 324show, 246–247, 329, 363show atm pvc, 329show dial-peer voice, 243show frame-relay fragment, 294–295, 297show frame-relay vofr, 292–293show interface, 330show running-config, 245show voice port, 245shutdown, 185signal, 185, 189signal pattern, 237signal-type, 235test, 248–249timeout interdigit, 212timeouts initial, 212timing, 212–213type, 190–191vad, 227vbr-rt, 322vofr, 271–274voice bandwidth, 276–278voice class permanent, 236voice confirmation-tone, 198voice local-bypass, 214voice vad-time, 213voice-card, 239voice-port, 182–183

companding, 59compand-type command, 195comparing

E1 and T1 lines, 80key systems and PBXs, 398voice compression techniques, 64voice-capable and standards-based routers, 121

components of AVVID, 372–373

access gateways, 375CallManger, 373Cisco IP Phones, 375uOne, 374

of basic PBX architecture, 410

compression, 61, 431. See also compandingdegradation of voice quality, 70HCMs (high-performance voice-compression

modules), 159–160hybrid, 63–64techniques

codecs, 193–194comparing, 64

vocoder, 62–63wave form, 62

concentrators, MC3810analog voice cable connections, configuring,

166–167BRI voice module, configuring, 163–164digital chassis, configuring, 160–161hardware installation, verifying, 167–168interface ports, configuring, 156, 158, 160MFT options, configuring, 162–163trunk options, configuring, 161

configuration commands, ATMdial-peer voice voatm, 324encapsulation, 320inarp parameter, 325interface atm, 319mode, 316, 318–319pvc name, 319session target, 324vbr-rt, 322

configuringABCD bit pattern for trunks, 237, 239analog voice ports, 182–183Cisco 2600 routers, 147–148Cisco 3600 routers, 148, 150–151

port addressing, 155VIC selection, 154–155VNM selection, 152

controllers, 215–216dial peers, 223–224, 229–230, 244, 328–329

voice-over, 229–242digital voice ports, 183E1 controller settings, 217, 219fragmentation, 358

end-to-end FRF.12, 283Frame Relay, Cisco proprietary, 284FRF.11 Annex C fragmentation for data

traffic, 283Frame Relay map classes, 275

commands

501

FRF.11 trunk calls, 287–288local dial peers, 224–227, 229MC3810

BRI voice module, 163–164digital chassis, 160–161interface ports, 156, 158MFT options, 162–163WAN trunk options, 161

MC3810 for voice-over, 165MLPPP, 361packet classification schemes, 349PQ-WFQ, 282, 356private-line calls, 286–287RTP header compression, 351VoATM, 322VoFR

CIR, 284PVCs, 284–285tandeming, 289, 291

voice cards, 239voice ports

E&M, 189–195ISDN PRI, 221, 223tie-line connections, 201–202

voice-over dial peers, session targets, 233–234WFQ, 282

confirmation tone, 38congestion

BECN, 260management, 350telephone networks, 38

connection command, 197connection sequence, H.323, 340–341connection tie-line command, 201connection trunk command, 202–203connections

E1, 78framing, 78line coding, 79

FXO, 128local, 123off-net, 124on-net, 123on-to off-net, 126PLAR, 124

T1, 71–72clocking, 76–77D4 framing pattern, 73ESF, 74–76line coding, 76–77management channel, 74–76Ones Density rule, 76–77robbed bit signaling, 73–74

tie-line, 125conserving bandwidth, 381–383

digital speech interpolation, 65constant bit rate (CBR), 308control complex, 400control signaling, 418controller command, 215controllers, configuring, 215–216conversational quality speech (ITU-T), 68converting analog signals to digital

compression, 61hybrid compression, 63–64vocoder, 62–63wave form compression, 62

encoding process, 60–61quantization process, 58–60sampling, 56–57

core layer, 11in new-world networks, 19

correcting input levels on voice ports, 210cost/benefit analysis, integrated voice/data

networks, 439global firms, 446, 448multinational firms, 470–471pan-European firms, 460–461

cptone command, 185CPUs, PBX processing network design, 407CQ (Custom Queuing), 353creating peer configuration table, 328CS-ACELP (conjugate structure-algebraic code

excited linear predictive), 64, 432CTIs (computer telephony interfaces), 401, 422–423

CTIs (computer telephony interfaces)

502

DD4 framing pattern, 73data link layer, VoIP protocol stack, 337data networks, 6

Frame Relay, 15–16leased-line, 7traffic shaping, 314voice/data integration, 132voice-date integration, 131

data queuing methodsCBWFQ, 354–355CQ, 353FIFO, 352LLQ, 356–358PQ, 352WFQ, 353

data traffic, FRF.11 Annex C fragmentation, example configuration, 283

databases, SS7, 83DE (Discard Eligible) bit, 265debug ccfrf11 session command, 297, 299debug ccswvoice vofr-debug command, 299debug ccswvoice vofr-session command, 299debug command, 331debug commands, 248, 362–363debug frame-relay fragment command, 300–301debug voice vofr command, 301–302decibel levels, calculating, 205degradation of voice quality in compression

schemes, 70de-jitter buffers, 17, 259, 435delay, 17

ATM, minimizing, 310dejitter buffers, 435integrated voice/data networks, 427jitter, 431packetization delay, 436processing delay, 434propagation delay, 434queuing delay, 435serialization delay, 434

delay budget, 336calculating, 435, 437–438

delay-start signaling, 35deregulated telecommunications markets, network

cloud terminology, 7

description command, 185, 216designing networks

auditing current network, 428–429global firms, 440multi-national firms, 463pan-European firms, 449

capacity planning, 438–439global firms, 445multinational firms, 468–470pan-European firms, 453, 456–458

case studies, 440global firm, 440, 443, 446, 448multinational firm, 462–471pan-European firm, 449–461

establishing technologies guidelines, 430–434delay budgets, 436–438global firms, 444multinational firms, 464–468pan-European firms, 452–453

financial analysis, 439global firms, 446–448multinational firms, 470–471pan-European firms, 460–461

reviewing technologies and services, 430global firms, 441–443multinational firms, 464pan-European firms, 450

setting objectives, 429global firms, 441multi-national firms, 463pan-European firms, 450

destination pattern, 123destination-pattern command, 224, 230devices

analog access gateways, 375AVVID

Cisco conference bridges, 391–392Cisco WebAttendant, 392gateways, 386–387, 389IP Phones, 384–385media convergence servers, 389–390

codecs, 56destination patterns, 123drop-and-insert, 12switches, 39

CO, 40–41intermediate, 41

D4 framing pattern

503

PBXs, 41voice, 40

DHCP (dynamic host configuration protocol)in AVVID, 376

dial peers, 179call legs, 181configuring, 223–224, 244, 328–329E.164 telephone numbers, configuring, 225example configuration, 242local, configuring, 224–227, 229POTS, 181verifying configuration, 243voice-over, 181

configuring, 229–242session targets, 233–234

dial tone, 38dialers, 27dial-peer voice command, 224dial-peer voice voatm command, 324dial-type command, 187DID (direct inward dial), 420

trunks, 48wink start signaling, 418

DiffServ, 349digital chassis (MC3810), configuring, 160–161digital signals, conversion from analog

compression, 61–64encoding process, 60–61Nyquist theorem, 57quantization process, 58–60sampling, 56–57

digital trunksgateways, 386T1/E1 packet voice trunk, Cisco 2600/3600

series routers, 103–104digital voice networks, 6digital voice ports

configuring, 183–184disabling, 185

dispersed control PBXs, 405displaying

function callsccfrf11 , 297–299ccswvoice, 299–300

VoFR call setup information, 301–302distributed control PBXs, 404

distribution layer, 10in new-world networks, 19

DLCIs (data-link connection identifiers)assigning to Frame Relay subinterface, 270–271bandwidth, reserving, 275VoFR, enabling, 271–274

DPNSS (Digital Private Network Signaling System), 18

drop-and-insert, 12ds0-group timeslots type command, 218–220DS1, 71. See also T1

digital signal Superframe format, 72DSCP (DiffServ Code Point), 265DSP (digital signal processor) modules

digital speech interpolation, 65on AS5300s, 170selecting, 172

DTMF (dual-tone multi-frequency), 37DVM (digital voice module)

architecture, 160–161mode cas command, 317

EE&M signaling

Type I lines, 42–43Type II lines, 43Type III lines, 44Type IV lines, 44Type V lines, 46

E&M trunk seizure, 32–36delay-start signaling, 35disconnect, 36immediate-start signaling, 36wink-start signaling, 34–35

E&M voice ports, 33–34call completion, enabling, 191–193Cisco 2600/3600 series routers, 102configuring, 189–195signaling type, specifying, 189VICs, 127–129

E.164 telephone numbers, dial peer configuration, 225

E.164 telephone numbers, dial peer configuration

504

E1Catalyst 6000 Voice E1 module, 388channel signaling, 78comparing to T1, 80controller settings, configuring, 217–219framing, 78line coding, 79

echo, 49–50echo cancel coverage command, 209echo-cancel enable command, 208ECMA (European Computer Manufacturer’s

Association), 18enabling

call completion on E&M voice ports, 191–193Frame Relay on interfaces, 270

encapsulation, MLPPP, 132encapsulation command, 320encapsulation frame-relay command, 270encoding, 60–61end-to-end FRF.12 fragmentation, example

configuration, 283enterprise networks

FXO, 128H.323, 139hoot-and-holler applications, 138–139OPX connections, 138PBX implementations, 400–401toll bypass, 137

enterprise telephony, 20erlangs, 416ESF (Extended Superframe Format), 74–76establishing voice quality guidelines, 431

coding/compression, 431fixed delay components, 434MOS, 432–433variable delay components, 435

Ethernet Phone, 130example configurations

Cisco-trunk calls, 286–287dial peers, 242PQ-WFQ, 282VoATM, 322, 326–328VoFR

CIR, 284Cisco proprietary fragmentation, 284end-to-end FRF.12 fragmentation, 283

FRF.11 trunk calls, 287–288PVCs, 284–285tandeming, 289–291

WFQ, 282Extended Superframes, 72–74external networks, 401

Ffast busy signal, 38fast packet switching, PBXs, 415fax-to-fax connections, 130FDM (frequency division multiplexing), 6feature cards

circuit cards, PBX systems, 412Cisco AS5300, 170Cisco AS5800 Voice Feature card, 111MICA (modem ISDN channel

aggregation), 170VOIP, selecting, 171–172

features of PBXs, 420–421FECN (forward explicit congestion notification),

260FIFO (First In First Out) queuing, 352first-generation private telephony systems, 400fixed delay

processing delay, 258propagation delay, 257serialization delay, 258

fixed prioritization, 314–316formulas for calculating bandwidth, ATM, 312–314forward-digits command, 228fragmentation, 266, 358, 280

Cisco proprietary (Frame Relay), example configuration, 284

FRF.11 Annex C, example configuration, 283MLPPP, configuring, 361PDU size, calculating, 268–269

Frame Relay, 15–16. See also VoFRfragmentation, 280map classes, configuring, 275

frame synchronization, D4 framing pattern, 73frame-relay adaptive-shaping command, 281frame-relay bc command, 281frame-relay be command, 281frame-relay cir command, 280

E1

505

frame-relay fair-queue command, 278–279frame-relay fragment command, 279–280frame-relay interface dlci command, 270–271frame-relay mincir command, 280frame-relay traffic-shaping command, 274frame-relay voice bandwidth command, 275frames, prioritizing, 260framing command, 216framing patterns

DS1, 71E1, 78ESF, 74, 76

FRF.11 Annex C fragmentation, 260configuring for data traffic, 283subchannels, displaying information, 292–293trunk calls, configuring, 287–288

FRF.12 fragmentation, 260example configuration, 283

fricatives, 63FRTS (Frame Relay traffic shaping), 260–261FXO (foreign exchange office)

Cisco 2600/3600 series routers, 102trunks, 47–48, 128voice ports

dial type, specifying, 187terminating impedence, specifying, 208

FXS (foreign exchange station) applications, 129Cisco 2600/3600 series routers, 102trunks, 48voice ports

impedence, adjusting, 211ring frequency, specifying, 187

GG.711 standard (ITU-T), 66gain, adjusting, 206gatekeepers, 133–134, 338gateways, 338–340, 386–389

Catalyst 6000 Voice T1 module, 388Cisco AS5300, 107Cisco AS5800, 110–112digital trunk gateways, 386H.323, 141VG 200 VoIP gateway, 387–388

GF (Generic Feature), Q.SIG, 83GF (generic functional) sublayer (QSIG), 419glare, 30goals of uOne, 374ground start signaling, 30–32, 418

specifying for voice ports, 186GSTN (global system telephone network), 373guaranteed traffic rates, FRTS, 261

HH.225 protocol, 341H.245, 341H.323, 139, 338–342

connection sequence, 340–341gateways, 340H.225, 341H.243, 341in AVVID, 377IP Phone, 130media formats, 379signaling, 340terminals, 339

handsets, 26hardware

AVVIDCisco conference bridges, 391–392Cisco WebAttendant, 392gateways, 386–387, 389IP Phones, 384–385media convergence servers, 389–390

VoATM, 310–311MC3810

analog voice cable connections, 166–167installation, verifying, 167–168

Hawking, Stephen, 63HCMs (high-performance voice-compression

modules), 159–160Cisco MC3810, 107

HDB3 (high density bit 3), 78HDV (High Density Voice) NM, 103high availability on MCS-7822 media convergence

server, 389high density bit 3 (HDB3), 78high-utilization trunks (HUTs), 49holding time per call, calculating, 417

holding time per call, calculating

506

hoot-and-holler, 138–139hunt groups, 392HUTs (high-utilization trunks), 49hybrid compression, 63–64

2- to 4-wire, balanced, 27, 49

IIDF (intermediate distribution frame), 402IMA cards, 311immediate-start signaling, 36impedence command, 208, 211implementing

IP voice installations, building blocks, 349–350VoIP with MGCP, 342

improving voice quality, 205–214inarp parameter, 325information signaling, 38, 417

alerting indicators, 38call progress indicators, 38

input gain command, 206, 215input power levels

correcting on voice ports, 210baselining, 205

installation, verifying for Cisco 3600 series routers, 156

integrated voice/data networksdelay, 427

propagation delay, 427delay budget, calculating, 435, 437–438design process

auditing network inventory, 428–429capacity planning, 438–439case studies, 440–471establishing technologies guidelines,

430–434delay budgets, 436–438financial analysis, 439reviewing technologies and services, 430setting network objectives, 429

interexchangenetworks, 401interface atm command, 319interface cards. See VICs

interfacesE&M, 33–34in PBXs, 413MC3810, configuring, 156–160

intermediate switches, 41inter-office trunks (IOTs), 49interpolation, 65intertandem trunks (ITTs), 49IOTs (inter-office trunks), 49IP Phones, 375, 384–385

Cisco IP Phone 7910, 384Cisco IP Phone 7960, 385

IP Precedence, 265, 337IP protocols in AVVID

DHCP, 376H.323, 377MGCP, 378–379SCCP, 379TFTP, 376

ISDN (Integrated Services Digital Network), 6BRI VoIP, 104network architecture, 81network protocols, 82PRI, voice port configuration, 221–223

ISO 3166 country name standards, 185ITTs (inter-tandem trunks), 49ITU-T Recommendation I.451, 419–420IVR (interactive voice response), 20, 422

J-K-LJ1, 80jitter, 17, 431

dejitter buffers, 435

key systems, 397–399

large-scale voice/data routersCisco 7200 series, 112–114Cisco 7500 series, 114, 117Cisco AS5800, 110–111

latency. See delaylayers of VoIP protocol stack, 337–338LCR (least-cost routing), 420LD-CELP (low-delay CELP), 63

hoot-and-holler

507

LD-CELP (low-delay code-excited linear-predictive) algorithms, 432

leased line networks, 7point-to-point, 8multi-drop, 9

least-cost routing (LCR), 420LECs (local exchange carriers), 6legacy PBX systems, 397legacy telephony systems

PBXs, 399–401private key systems, 398–399

limitations of bandwidth, voice-grade telephony channels, 57

line circuit cards in PBX systems, 412line coding

E1, 79T1, 76–77

line interface circuitry, PBX systems, 411–412line provisioning, 438–439linecode command, 216–217listener echo, 49–50LLQ (Low Latency Queuing), 337, 356–358local calls, 123local connections, 123local dial peers, configuring, 224–229local loop, 39

ground start signaling, 30–32loop start signaling, 28–30

local networks, 401logical voice ports, 219long data frames, 260loop start circuits, 28loop start signaling, 28–30, 418

specifying for voice ports, 186loopback command, 234loop-timed command, 216loss-plan command 206, 210low-delay CELP (code excited linear predictive)

coding, 63

Mmain system controller (PBXs), 410maintaining synchronization over digital

interfaces, 81make/break cycle, 36

management channel, T1 line coding, 74, 76map classes, configuring, 275map-class frame-relay command, 275marking, 265MC3810 routers

analog voice cable connections, 166–167BRI voice module, configuring, 163–164digital chassis, configuring, 160–161fixed prioritization, 314–316hardware installation, verifying, 167–168interface ports, configuring, 156, 158, 160MFT (multiflex trunk module) options,

configuring, 162–163synchronous serial connections, 167voice-over configuration, 165WAN trunk options, configuring, 161

MCM (Multimedia Conference Manager), 133–134, 139

MCS-7822, 389MCS-7835, 390MCU (multipoint control unit), 339MDF (main distribution frame), 402measuring

PBX traffic handling, 416–417speech quality, 68, 70–71

PSQM, 69subjective, MOS, 432–433telephone voice quality, 65

media convergence serversfor AVVID, 389–390MCS-7822, 389MCS-7835, 390

media formats, H.323, 379Meet-Me conferences, 391Megaco, 342MELCAS (Mecury Exchange Limited), 317messaging

Q.931 signaling, 419–420unified messaging, 141uOne, 374voice-mail systems, 422

MFT (Multiflex Trunk), 311configuring on MC3810, 162–163VWIC, 103

MFT (Multiflex Trunk)

508

MGCP (Media Gateway Control Protocol), 18, 338, 342

configuring on MC3810, 162–163MICA (modem ISDN channel aggregation, 170minCIR (minimum committed information rate),

260minimizing delay in VoATM, 309–310MLPPP (Multilink Point-to-Point Protocol), 360

configuring, 361encapsulation, 132

mode cas command, 317mode ccs command, 218mode command, 316, 318–319modular wiring, PBX systems, 411modulation, B8ZS, 77monitoring commands, 329–331MOS (mean opinion score), 68, 432–433MTP (media termination point), 382multicast conference bridges, 391multi-drop networks, 8–9multiflex trunking, 457Multiframes, 79multipoint controller, 339multiservice networks

voice/date integration, 131voice-over technology, selecting, 132

multiservice routersCisco AS5300, 107Cisco MC3810, 105–107

Nnetwork design

access layer requirements, 9new-world networks, 18

auditing current network, 428–429global firms, 440multi-national firms, 463pan-European firms, 449

capacity planning, 438–439global firms, 445multinational firms, 468–470pan-European firms, 453, 456–458

case studies, 440global firm, 440–448multinational firm, 462–471pan-European firm, 449–461

circuit-switched, 13core layer requirements, 11, 19distribution layer requirements, 10, 19establish technologies guidelines, 430–434

delay budgets, 436–438global firms, 444multinational firms, 464–468pan-European firms, 452–453

financial analysis, 439global firms, 446–448multinational firms, 470–471pan-European firms, 460–461

reviewing technologies and services, 430global firms, 441– 443multinational firms, 464pan-European firms, 450

setting objectives, 429global firms, 441multi-national firms, 463pan-European firms, 450

shared, 12traditional, 5

data, 6–7voice, 5–6

network layer (VoIP protocol stack), 337Network Module-Inverse Multiplex ATM (NM-

IMA), 311network protocols, ISDN, 82network-clock-select command, 164new-world telephony models, AVVID, 373

access gateways, 375CallManager, 373Cisco conference bridges, 391Cisco IP Phones, 375Cisco WebAttendant, 392Cisco’s role in, 18–20DHCP, 376gateways, 386–387, 389H.323, 377IP Phones, 384–385media convergence servers, 389–390MGCP, 378–379SCCP, 379

MGCP (Media Gateway Control Protocol)

509

signaling, 380TFTP, 376uOne, 374

NM-IMA (Network Module-Inverse Multiplex ATM), 311

NMs (network modules), HDV (High Density Voice), 103

non-linear command, 209non-real time service classes, 314, 316num-exp command, 226Nyquist theorem, 56–57

Ooff-hook state, 28off-net calls, 124off-net connections, 124old-world telephony models, 371. See also

new-world telephony modelsPBXs, 397, 402ACD, 421–422

adjunct control, 406architecture, 408–414automated attendant, 421busy hour call handling, 415–416callout, 416–417centralized control, 403circuit switching, 414client/server-based, 407–408CTI, 422–423dispersed control, 405distributed control, 404fast packet switching, 415features, 420–421IVR, 422line interfaces, 412packet switching, 415processing network design, 407switching network design, 403trunk interfaces, 413Windows/Unix server-based, 407wiring, 413–414

private systemskey systems, 398–399PBXs, 399, 401

Ones Density rules, 76–77, 80on-hook state, 28on-net connections, 123on-to off-net connections, 126oos (out-of-service) receive pattern, 237operation command, 189options

dial-peer voice voatm command, 324encapsulation command, 321interface atm command, 319mode command, 317pvc command, 320session target command, 325vbr-rt command, 322, 324

OPX connections, 138output attenuation command, 206, 215output power levels, baselining, 205

Ppacket switching, PBXs, 415packetization delay, 436packets

classification schemes, 349fragmentation, 266, 358SAR, 309scheduling, 264sequencing, 343–344time-stamping, 343–344

payback period, calculating for capital investments, 460–461

PBXs (private branch exchanges), 6, 41, 397–399, 401–402

ACD, 421–422architecture, 408, 410–414

cabinet/shelf controller, 409main system controller, 410wiring, 413–414

automated attendant, 421busying out, 237circuit switching, 414CTI, 422–423fast packet switching, 415features, 420–421grounding, 42in enterprise networks, 401

PBXs (private branch exchanges)

510

IVR (interactive voice response), 422legacy systems, 397line interfaces, 412local loop, 39old-world telephony model, 371packet switching, 415processing methods

busy hour call handling, 415–416callout, 416–417circuit/packet switching, 414–415

processing network design, 407client/server-based, 407–408Windows/Unix server-based, 407

switching network design, 403adjunct control, 406centralized control, 403dispersed control, 405distributed control, 404

tandem switching, disadvantages in voice networks, 137

terminal interfaces, 400tie-lines, 32trunk interfaces, 413trunks, 46–47

CO trunks, 47DID/DOD trunks, 48FXO trunks, 47–48private trunk lines, 47telco trunks, 48

voice-mail systems, 422PBX-to-PBX calls, 125peak options for voice traffic, calculating, 323–324peer configuration table, VoATM, 328Perceptual Speech Quality Measurement

(PSQM), 69permanent calls. PLAR connections, 199per-VC queuing, enabling on PVCs, 274physical connectivity, MC3810, 166–167physical layer, VoIP protocol stack, 337pilot number, 374PINX (private integrated network exchange), 163–

164QSIG, 419

placing a call, 23–26PLAR (private line automatic ring-down), 124, 198

off-premises extension, 200

point-to-point connections, enterprise networks, 138–139

point-to-point networks, 8policing, 264port addressing, Cisco 3600 routers, 155port circuit cards, PBX systems, 412

controller, 410port command, 225–226POTS, dial peers, 181, 328power failure transfer, 421power supply, telephones, 40PQ (priority queuing), 352PQ-WFQ (priority queuing-weighted fair queuing),

355–356example configuration, 282

prefix command, 228presentation layer, VoIP protocol stack, 338prioritizing voice frames, 260private networks, 401private phone systems, 397private telephony systems

first-generation, 400key systems, 398–399PBXs, 399, 402

ACD, 421–422adjunct control, 406architecture, 408, 410–414automated attendant, 421busy hour call handling, 415–416callout, 416–417centralized control, 403circuit switching, 414client/server-based, 407–408CTI, 422–423dispersed control, 405distributed control, 404fast packet switching, 415features, 420–421IVR, 422line interfaces, 412packet switching, 415processing network design, 407switching network design, 403terminal interfaces, 400trunk interfaces, 413Windows/Unix server-based, 407wiring, 413–414

PBXs (private branch exchanges)

511

second-generation, 400third-generation, 400

private trunk lines, 47private-line calls, example configuration, 286–287processing delay, 258, 434processing methods, PBXs

busy hour call handling, 415–416callout, 416–417switching, 414–415

processing network designs (PBXs)client/server-based, 407–408Windows/Unix server-based, 407

propagation delay, 257, 434integrated voice/data networks, 427

protocol stack, VoIP, 337–338PSQM (Perceptual Speech Quality

Measurement), 69PSTNs (private switched telephone networks).

See also old-world telephonyaccess code, 124access numbers, pilot number, 374FXO interfaces, 128

PTT (Post, Telephone, and Telegraph) agency, 7pulsed digits, 36pvc name command, 319PVCs (permanent virtual circuits), 13

fragmentation, displaying information, 300–301

per-VC queuing, enabling, 274traffic shaping, 260–261virtual template parameters, 321WFQ, enabling, 278–279

PVDM (Packet Voice DSP Module), 103

QQ.931 signaling, 419–420Q.SIG, 83, 419Q.SIG GF (Generic Features), 83QoS (quality of service)

applying to VoFR, 264–265fragmentation size, calculating, 268–269

quantization, 58–60

queue management, 350CBWFQ, 354–355data transmission

CQ, 353FIFO, 352PQ, 352

LLQ, 356, 358PQ-WFQ, 355–356RTP header compression, 350–351WAN edge queuing techniques, 351WFQ, 353

queuing, 264delay, 259, 435PQ-WFQ, example configuration, 282WFQ, example configuration, 282

Rrate queues, 326real time service classes, 314–315RED (Random Early Detection), 350regional offices, redesigning for voice traffic, 454regulated telecommunications markets, network

cloud terminology, 7reorder, 38reserving bandwidth on DLCIs, 275residual echo suppression, 210ring frequency command, 187ring number command, 186ring-back, 38ringer, 27robbed bit signaling, 73–74, 417

ABCD format, 74–76rotary telephones

pulsed digits, 36routers

Cisco 1750 series, 91Cisco 2600 series, 92, 94

configuring, 147–148digital T1/E1 packet voice trunk, 103–104PVDM, 103VICs, 102voice/fax network module, 101–102

routers

512

Cisco 3600 series, 95Cisco 3620 modular access routers, 95Cisco 3640 modular access routers, 95Cisco 3660 modular access routers, 95configuring, 148–151digital T1/E1 packet voice trunk, 103–104PVDM, 103VICs, 102, 154–155VNM, selecting, 152voice/fax network module, 101–102

Cisco 7200 series, 112–114Cisco 7500 series, 114, 117Cisco AS5300, 107Cisco AS5800, 110–112Cisco MC3810, 105–107signaling

between routers, 346to PBX, 347

voice-over connection types, 123–126RSVP (Resource Reservation Protocol), 344RTP header compression, 343–344, 350

configuring, 351

Ssampling, Nyquist theorem, 56–57SAP (Session Announcement Protocol), 342SAR (segmentation and reassemby), 309SCCP (signaling connection control part),

AVVID, 379scheduling, 264second-generation private telephony systems, 400selecting

DSP modules, 172network technology, 430

global firms, 441, 443multinational firms, 464pan-European firms, 450

VICs, Cisco 3600 routers, 154–155VNMs, Cisco 3600 routers, 152voice-over technologies, 132

VoATM, 135–136VoFR, 134

VOIP feature cards, 171–172sequencing packets, 343–344serialization delay, 258, 358, 434

server farms, 408service circuit cards, PBX systems, 412service classes (ATM), 308–309

minimizing delay, 310non-real time, 314–316real time, 314–315

service provider telephony, 20VPNs, 402

session layer, VoIP protocol stack, 338session target command, 231–234, 324session targets, configuring on voice-over dial peers,

233–234setting network objectives, 429

global firms, 441multi-national firms, 463pan-European firms, 450

shaping traffic, 264shared networks, drop-and-insert devices, 12show atm pvc command, 329show commands, 246–247, 329, 362–363show dial-peer voice command, 243show frame-relay fragment command, 294–295, 297show frame-relay vofr command, 292–293show interface command, 330show running-config command, 245show voice port command, 245shutdown command, 185sidetone, 27signal command, 185, 189signal pattern command, 237signaling, 27, 417

AVVID, 380between routers, 346CAS, 79, 317CCS, 317, 418–419delay-start, 35DID wink start, 418E&M

disconnect, 36seizure, 32, 34–35Type I lines, 42–43Type II lines, 43Type III lines, 44Type IV lines, 44Type V lines, 46

E1 channel, 78from router to PBX, 347

routers

513

glare, 30ground start, 418H.323, 338, 340–342

H.225, 341H.245, 341

immediate-start, 36information, 38local loop

ground start signaling, 30, 32loop start signaling, 28, 30

loop start, 418Q.931, 419–420Q.SIG, 83, 419specifying type for voice ports, 185, 189supervisory, 28

local-loop seizure, 28, 30, 32VoIP, 345wink-start, 34–35

signal-type command, 235silence suppression, VAD, 227SIP (Session Initiation Protocol), 18, 342smoother circuits, 60SOT (service order threshold), 353specifying

BVMs as clock source, 164confirmation tones for voice ports, 198signaling type for voice ports, 185

speech qualityestablishing guidelines, 431

coding/compression, 431fixed delay components, 434MOS, 432–433variable delay components, 435

measuring, 65, 67MOS (mean opinion score), 68, 70–71toll-quality, 67transparent quality (ITU-T), 67

SS7 (Signaling System 7), 82SSCP (Skinny Station Control Protocol), 379subjective speech measurement, MOS, 68–71,

432–433sublayers of QSIG, 419Superframes, 72supervisory signaling, 28, 417

local-loop seizure, 28–32SVCs (switched virtual circuits), 13switch hook, 27

switched callsPLAR connections, 199tandeming, configuration, 289, 291

switching, 39, 400circuit switching, 414CO, 40–41fast packet switching, 415intermediate switches, 41packet switching, 415PBXs, 41–42

adjunct control, 406centralized control, 403dispersed control, 405distributed control, 404

voice switches, 40symptoms of poor QoS, 266synchronization

D4 framing pattern, 73time-slot, 80

synchronous serial connections, for MC3810, 167synthetic quality speech (ITU-T standard), 68system circuit cards, PBX systems, 412system processor bus, PBX design, 409system-wide PBX features, 420–421

TT1 line coding, 71–72, 76–77

Catalyst 6000 Voice T1 module, 388clocking, 76–77comparing to E1, 80controller settings, 216–217D4 framing pattern, 73ESF (Extended Superframe Format), 74, 76management channel, 74, 76Ones Density rules, 76–77robbed bit signaling, 73–74

tagging, 265talk slots, 417talk spurts, 259talker echo, 49–50tandeming, 289–291

disadvantages in voice networks, 137TCD (telephony call dispatcher), 392TDM cross connect. See drop-and-inserttelco trunks, 48

telco trunks

514

telephony systemsconfirmation tone, 38devices, 26–27glare, 30GSTN (global system telephone network), 373off-hook state, 28old-world

key systems, 398–399PBXs, 399, 401

on-hook state, 28power supply, 40private

first-generation, 400PBXs, 402second-generation, 400third-generation, 400

switches, 39CO switches, 40–41intermediate switches, 41PBXs, 41voice switches, 40

third-generation, 400terminal interfaces, 400terminals, 339test commands, 248–249TFTP (trivial file transport protocol), AVVID, 376third-generation private telephony systems, 400tie-line connections, 32, 125, 129

voice port configuration, 201–202time slots, 417timeouts initial command, 212timeouts interdigit command, 212time-slot synchronization, 80time-stamping, UDP packets, 343–344timing command, 212–213toll bypass, 137toll quality speech

G.711 standard, 66ITU-T standard, 67

ToS (type of service) bits, 349

traditional networks, 5data networks, 6–7delay, 17jitter, 17shared, 12voice, 5–6

trafficclasses, 308–309

minimizing delay, 310non-real time, 314–316real time, 314–315

congestion management, 350packet classification schemes, 349policing, 264queuing, 264scheduling, 264voice/data integration, 132

traffic shaping, 260–261, 264ATM, 312for data/video, 314voice traffic

calculating average options, 323–324calculating burst options, 323–324calculating peak options, 323–324

transcoding, 389transparent quality speech, 67transport layer, VoIP protocol stack, 338troubleshooting commands, 329–331, 362

debug commands, 363show commands, 363

troubleshooting QoS, 269trunks, 46–47

ABCD bit pattern, configuring, 237, 239CO trunks, 47DID/DOD trunks, 48digital trunk gateways, 386FXO trunks, 47–48FXS trunks, 48interfaces, 411–413line provisioning, 438–439MC3810, setting options for, 161MFT (Multiflex Trunk), 311private trunk lines, 47service cards, 412telco trunks, 48voice classes, configuring, 236

telephony systems

515

tuning voice port quality, 205–207, 209–214two-way communication, VoATM, 328type command, 190–191Type I E&M lines, 42–43Type II E&M lines, 43Type III E&M lines, 44Type IV E&M lines, 44Type V E&M lines, 46

UUBR (unspecified bit rate), 308UDP (user datagram protocol), time-stamping

packets, 343–344unacceptable telephone voice quality, 66unicast conference bridges, 391unified messaging, 141Unix server-based PBXs, 407unsatisfactory speech quality (ITU-T standard), 68unspecified bit rate (UBR), 308uOne, 374upgrading networks, pan-European firms, 455–458user features for PBX, 420–421

VVAD (voice activity detection), 65vad command, 227variable bit rate (VBR), 308variable delay

de-jitter buffers, 259queuing delay, 259WAN/service provider delay, 259

variation. See also delayVBR (variable bit rate), 308VBR-nrt (non-real time), 308VBR-rt (real time), 308vbr-rt command, 322VC (virtual circuit) queues, VoATM networks, 135verifying

dial peer configuration, 243hardware installation

Cisco 3600 routers, 156MC3810, 167–168

VFCs (voice feature cards), Cisco AS5800, 111. See also feature cards

VG 200 VoIP gateway, 387–388VICs (voice interface cards)

assembly, 155Cisco 2600/3600 series routers, 102E&M, 127port addressin, Cisco 3600 routers, 155selecting, 154–155

virtual circuits (VCs), 13VNMs

assemby, 155selecting, 152

VoATM, 135–136bandwidth allocation, 309dial peers, configuring, 328–329example, 326, 328example configuration, 322hardware, 310–311peer configuration table, 328VC queues, 135

vocoder compression, 62–63VoFR, 134

CIR, example configuration, 284Cisco implementation, 262

benefits of, 263restrictions, 264

enablingn on specified DLCI, 271–274PVCs, example configuration, 284–285QoS, applying, 264–265tandeming, 289, 291

vofr command, 271–274voice bandwidth command, 276–278voice calls, calculating bandwidth, 359–360voice cards, configuring, 239voice class permanent command, 236voice compression

codec complexity, 240comparing techniques, 64

Voice Feature cards, Cisco AS5800, 111voice gateways

Cisco AS5300, 107Cisco AS5800, 110–112

voice local-bypass command, 214

voice local-bypass command

516

voice networks, 5. See also integrated voice/data networks

analog, 6capacity planning, 438–439

global firms, 445multinational firms, 468–470pan-European firms, 453, 456–458

delay, 427delay budget, calculating, 435, 437–438digital, 6echo, 49–50echo cancellation, 50echo suppression, 50financial analysis, 439

global firms, 446–448multinational firms, 470–471pan-European firms, 460–461

voice ports, 179analog, configuring, 182call progress tone, setting, 185confirmation tones, specifying, 198connection mode, specifying, 197decibel levels, calculating, 205digital, configuring, 183disabling, 185E&M

call completion, enabling, 191–193configuring, 189–195

FXOdial type, specifying, 187impedence, adjusting, 211terminating impedence, specifying, 208

FXS, specifying ring frequency, 187input/output power levels

baselining, 205correcting, 210

ISDN PRI, configuring, 221, 223logical, 219PLAR

off-premises extension, 200specifying, 198

residual echo suppression, 210signaling type, specifying, 185string description, adding, 185tie-line connections, configuring, 201–202timing parameters, adjusting, 212–213trunk connections, specifying, 202–203

tuning, 205–214voice quality

establishing guidelines, 431coding/compression, 431fixed delay components, 434MOS, 432–433variable delay components, 435

measuring, 65voice switches, 40Voice T1 and Services Module, 389voice vad-time command, 213voice/data integration, See integrated voice/data

networksvoice/fax network module, Cisco 2600/3600 series

routers, 101–102voice-card command, 239voice-confirmation-tone command, 198voice-grade analog channels, bandwidth, 56voice-mail systems, 422

AVVID, 16uOne messaging, 374

voice-over technologiesconnection types

local, 123off-net, 124on-net, 123on-to off-net, 126PLAR, 124tie-line, 125

dial peers, 181, 229–242MC3810, configuring, 165selecting, 132VoATM, 135–136VoFR, 134

voice-port command, 182–183voice-port tuning commands, 204VoIP

Cisco implementation, 347H.323, 338, 340–342ISDN BRI, 104signaling, 345

VPNs (virtual private networks), 402VWICs, MFT (MultiFlex Trunk), 103

voice networks

517

W-ZWANs

bandwidth, conserving over links, 381–383edge queuing techniques, 351fast packet switching, 415service provider delay, 259

wave form compression, 62WFQ (weighted fair queuing), 353

enabling for PVCs, 278–279example configuration, 282

WICs (WAN interface cards), MFT (MultiFlex Trunk) VWIC, 103

Windows server-based PBXs, 407wink signals, 418wink-start signaling, 34–35wiring, PBX systems, 413–414WRED (Weighted Random Early Detection), 350

X.25, 15–16

X.25