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COMSPHERE 3800 Series Modems
Glossary-2 November 1996 3810-A2-GB30-20
automatic dial backup When leased-line operation fails, this function forces the modem to dial the telephone
number stored in directory location 1; communication over the dial network continues
with the remote modem. For a 3800 Series modem to perform this properly, the
telephone number in directory location 1 must be the telephone number at the remote
site. Also, the Auto Dial Backup configuration option in one modem must be enabled
while the other modem must have the Auto Answer Ring Number configuration option
enabled.
automatic dial standby When operating in Dial Backup mode, this function forces the modem to periodically
check the quality of the leased line. If the leased line is found to be at normal operating
condition, the modem disconnects from the dial network and continues normal operation
over the leased-line network.
backbone network The primary route from a control modem to its first tributary when the communications
network contains extended controls.
backplane A common bus at the rear of the COMSPHERE 3000 Series Carrier connecting each
circuit card slot to the SDCP and/or SDU. It also distributes low-voltage ac power to
each slot.
baud
A unit of signaling speed that is equal to the number of symbols per second. This is not
necessarily the same as bits per second, although the terms are frequently interchanged.
Bisync
Binary Synchronous Communications. An IBM
communications protocol that has
become an industry standard. It uses a defined set of control characters and control
character sequences for synchronized transmission of binary-coded data between stations
in a data communications system.
bit A contraction of binary digit. A bit, which is the smallest unit of information, represents
the choice between a one or a zero (sometimes called mark or space).
bps
Bits per second. Indicates the speed at which bits are transmitted across a data
connection.
buffer A storage device used to compensate for differences in the data flow rate when
transmitting data from one device to another.
byte
A sequence of successive bits (usually eight) handled as a unit in data transmission.
Call Setup Top-Level menu branch that contains all the functions necessary to dial telephone
numbers stored in directory locations, answer incoming calls, disconnect calls, and save
telephone numbers to directory locations.
carrier The rack mounting that contains 17 slots: 1 control slot for an SDU and 16 modem slots.
See data carrier.
carrier-mounted A modem that is designed for installation in a COMSPHERE 3000 Series Carrier and
used at central-site operations. Up to 16 modems can be installed per carrier, with 6
carriers per cabinet.
CCITT An advisory committee (Consultative Committee on International T
elephone and
T
elegraph) established by the United Nations to recommend communications standards
and policies.