62f mapping into SDH, 536 analog-channel digital transmission, 267-278 mapping into SONET, 537 modulation-demodulation schemes in, 267-268 payload-type field, 519 analog signals, information content of, 107 routing field, 518 analog transmission, 29 structure of, 516-517 analog TV signal, PCM signal development from, transporting, 533-537 ATM convergence sublayer, MAC, 350 analog voice channel, 89 ATM layering, 521-526 angle of incidence, 232, 233f ATM link, 512 angular degrees, 28 ATM nodes, 527 of rotation, 25 atmospheric absorption, 226 angular frequency, 268 ATM reference model, 514 ANSI frame relay, 330 ATM switching, 527 ANSI/IEEE LAN protocols, 295-298 lending-alerting local switch function, 70 logical link control, 297-298 attenuation (loss), 32 relation to OSI, 295-297 coaxial cable, 245-246 Answered operating condition, 157 distortion, 45, 46, 269, 270f antenna aperture, increasing, 214. See also very- of loaded loops, 98 small-aperture terminal (VSAT) networks attenuation (loss) limits antenna noise, 224 calculating, 96-97 antenna separation, space diversity, 466 subscriber loop, 94-95 Appended bit, 135 attenuator, 32 applications, in troubleshooting, 543 audible-visual call progress signaling, 149, 150 a priori knowledge, 19 audio feedback, 52 area codes, 6, 67, 175 audio program channel, 413 ARP (address resolution protocol), 321-322 AUIs, MAC frame, 303 ARPANET (Advanced Research Projects Agency authentication header, SNMP, 557 Network), 319 authorization key (AK) update protocol, 358 ARP cache, 323 automatic alternative routing (AAR), 183-184 ARQ error correction, 257-258 automatic equalization, 276 aspect ratio, 404, 406 automatic line build-out (ALBO) networks, 121 associated channel signaling, 162-163 "automatic protection switching" techniques, 342 associated mode of signaling, 362 automatic rerouting (crankback, ARR), 184, 185 asymmetric digital subscriber line (ADSL), 128 automatic telephone switching systems, 71-72 asynchronous balanced mode (ABM), HDLC, Autovon (automatic voice network), 19