Adtran 4120 Manual Do Utilizador

Glossary

Glossary-2

Express 4110/4120 User Manual

61200176L3-1

In telephony, the phone company switching facility or center, usually a Class 5 end of-

fice, at which subscribers local loops terminate.  Handles a specific geographic area, 

identified by the first three digits of the local telephone number.  Usually the facilities 

of the local BOC. 

Carrier Sense Multiple Access Collision Detect.  A channel access mechanism where 

devices check the channel for a carrier before transmitting.  If no carrier is sensed for 

the specified period of time, the device can transmit.  If two devices transmit at once, a 

collision occurs and is detected by all colliding devices.  This collision subsequently de-

lays their retransmissions for a random length of time.  CSMA/CD is used by Ethernet 

and IEEE 802.3.

The ISDN channel that carriers signalling information to control the call setup, tear-

down, or invocation of supplementary services.  The D-Channel may also be used to 

provide packet mode data service.

Dataphone Digital Service.  AT&T private line service for transmitting data over a dig-

ital system.  The digital transmission system transmits electrical signals directly, in-

stead of translating the signals into tones of varied frequencies as with traditional 

analog transmission systems.  Digital techniques provide more efficient use of trans-

mission facilities, resulting in lower error rates and costs than analog systems.

Designated office where DDS channels are interconnected and where synchronous net-

work timing, testing access, and additional service features are provided.

A local area network used for connecting computers, printers, workstations, a termi-

nals, servers, etc., within the same building or campus. Ethernet operates over twisted 

wire and coaxial cable at speeds up to 10 Mbps.  Ethernet specifies a CSMA/CD. 

Telephone lines using two wires for transmitting and two wires for receiving, offering 

much higher quality than a 2-wire circuit.  All long distance circuits are 4-wire.  Almost 

all local phone lines and analog phones are 2-wire. 

A high-speed (56 kbps) facsimile protocol specific to ISDN.

A routing metric used to measure the distance between a source and a destination.  Par-

ticularly used by RIP.

(1) Communications center, (2) Major routing station for connecting channels, (3) DDS 

connecting center.