ADTRAN 1204006L1 Bedienungsanleitung PDF herunterladen (Seite 154)

138 FSU 5622 ESP User Manual 61200.175L1-1

Glossary

bridge also receives frame relay frames from the network, strips the frame relay

frame off each LAN frame, and passes the LAN frame on to the end device.

Bridges are generally used to connect LAN segments to other LAN segments or

to a WAN. They route traffic on the Level 2 LAN protocol (e.g. the Media Access

Control address), which occupies the lower sub-layer of the LAN OSI data link

layer. See also router.

CCITT

Consultive Committee for International Telephony and Telegraphy. A standards

organization that devises and proposes recommendations for international

communications. See also American National Standards Institute (ANSI).

carrier detect. A signal generated by a modem or DSU/CSU. CD indicates the

presence of a carrier signal on a communications link.

channel service unit

CSU. A device used to connect a digital phone line (T1 or Switched 56 line)

coming in from the phone company to either a multiplexer, channel bank, or

directly to another device producing a digital signal; for example, a digital PBX, a

PC, or data communications device. A CSU performs certain line-conditioning

and equalization functions, and responds to loopback commands sent from the

central office. A CSU regenerates digital signals. It monitors them for problems,

and provides a way of testing the digital circuit.

clocking

An oscillator-generated signal that provides a timing reference for a transmission

link. A clock provides signals used in a transmission system to control the timing

of certain functions. The clock has two functions, (1) to generate periodic signals

for synchronization and (2) to provide a time base.

CPE

Customer premise equipment. All telecommunications terminal equipment

located on the customer premises, including telephone sets, private branch

exchanges (PBXs), data terminals, and customer-owned coin-operated

telephones.

CRC

Cyclic redundancy check. A computational means to ensure the accuracy of

frames transmitted between devices in a frame relay network. The mathematical

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ADTRAN 1204006L1 Bedienungsanleitung Seite 154