Index_D

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D

Data communication network (DCN), 276

Data encryption. See Encryption

Data-link control (DLC) layer, 177

Data protection, 62–70

automated operations, 68–69

hardware solutions, 62–63

off-site storage, 69–70

RAIDs, 65–67

server blades, 67–68

software solutions, 63–65

Data terminal equipment (DTE), 20

loopback, 214

tests, 214

Dedicated token ring (DTR), 17

Dense wave division multiplexed (DWDM) fiber, 79

DesignXpert, 343, 345–46

Device libraries, 339–40

defined, 339

illustrated example, 339

See also Network documentation tools

Dial backup, 371–72

DDS, 373–75

defined, 371–72

illustrated, 372

Dial backup units (DBUs), 376

Differentiated Services (Diff-Serv), 110, 111–12, 239, 294

defined, 111

implementation, 112

PHB, 112

stateless approach, 111

See also Routing protocols

Digital cross-connect systems (DCSs), 183, 198–205

administration terminal, 204

based on space division switching, 199

carrier-provided service, 201

carrier-provided service subscription, 203

carrier-provider service selection, 202–4

control system, 200

customer-controlled reconfiguration, 199–202

defined, 198

functions, 198

groom-and-fill functions, 199

memory, 204

network implementation, 204–5

network management tasks, 204–5

node location, 204

shared, 199

in T-carrier environment, 198

See also TDM infrastructures

Digital data services (DDSs), 208–9

availability rate, 218

defined, 208

dial backup, 373–75

with secondary channel (DDS/SC), 209

Digital Encryption Standard (DES), 311–12

Digital interface frames (DIFs), 359

Direct inward dialing (DID), 177, 178

Direct outward dialing (DOD), 178

Disk/drive controls, 309–10

Disk duplexing, 64–65

defined, 64

disadvantage, 65

performance advantage, 64–65

Disk mirroring, 63

Disk pooling, 94

Disk recovery, 64

Distributed Management Task Force (DMTF), 92

Do-it-yourself maintenance/support, 382–90

operations management, 389–90

preventative maintenance, 383

resource requirements, 384

technical support, 388–89

user support, 384–88

Domain name servers, 131

Domain name system (DNS), 37

DSUs, 374

defined, 207

multiple, backups, 374

Dual tone multifrequency (DTMF) tones, 329

Dynamic Host Configuration Protocol (DHCP), 108, 131, 245–46

defined, 355

IP administration by, 245–46

for organization, 246

Dynamic multipathing (DMP), 94

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