ADTRAN Express 6100 Manual page 143

Glossary
of varied frequencies as with traditional analog transmission systems.
Digital techniques provide more efficient use of transmission facili-
ties, resulting in lower error rates and costs than analog systems.
digital hub
Designated office where DDS channels are interconnected and where
synchronous network timing, testing access, and additional service
features are provided.
Ethernet
A local area network used for connecting computers, printers, work-
stations, a terminals, servers, etc., within the same building or cam-
pus. Ethernet operates over twisted wire and coaxial cable at speeds
up to 10 Mbps. Ethernet specifies a CSMA/CD.
four-wire circuits
Telephone lines using two wires for transmitting and two wires for re-
ceiving, 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.
group 4
A high-speed (56 kbps) facsimile protocol specific to ISDN.
hop count
A routing metric used to measure the distance between a source and
a destination. Particularly used by RIP.
hub
(1) Communications center, (2) Major routing station for connecting
channels, (3) DDS connecting center.
61200176L1-1 Express 6100/6120 User Manual Glossary-3