COMSPHERE 3600 Series Data Service Units
Glossary-2 December 1996 3610-A2-GB46-60
auto backup A function of the dial backup module (DBM) or carrier-mounted dial backup unit, whereby the DSU
activates the DBM to reestablish a line automatically when a facility alarm is detected from the DDS
network.
auto restoral A function of the DBM whereby the DSU automatically returns to the DDS network when service is
restored over the private line. On point-to-point circuits, the DSU test the integrity of the DDS network
before switching data back to the private line.
backup See auto backup.
backbone network The main circuit that carries the data before it is split into extended circuits going to their final
destination.
bandwidth The range of electrical frequencies a device is capable of handling.
basic mode A mode of operation in which the single power module in the Central Office (CO) Power Unit supplies
power to the entire carrier.
B-channel Bearer Channel. ISDN 64 kbps bearer channel used for voice, circuit, or packet switched data.
BERT Bit Error Rate Test. A test used to analyze the network circuit. Both the control and tributary devices must
be connected to the network.
bis See V.32bis.
bit robbing Used with nondisruptive diagnostics when the data rate and port speed(s) are not equal.
bps Bits per second. Indicates the speed at which data is transmitted between devices.
BRI Basic Rate Interface. ISDN interface consisting of B-channel for information transfer and D-channel for
control and signaling.
bridge mode All ports are assigned to one digital-sharing group.
broadcast A method of transmission. The simultaneous transmission to two or more communicating devices.
callback directory
pointer
The directory entry in an originating DBM consists of the answering DBM’s telephone number, a
delimiting character, and a callback pointer. The pointer identifies the originating DBM’s telephone
number in the answering DBM’s Backup Directory.
capacitance The property of an electric nonconductor that permits the storage of energy as a result of electric
displacement.
carrier The rack mounting that contains 17 slots: 1 SDU control slot and 16 device slots.
carrier-mounted A Model 3611 DSU that is designed for installation in a COMSPHERE 3000 Series Carrier and used at
central-site operations. Up to 16 DSUs can be installed per carrier, with 6 carriers per cabinet.
CBrdg Central-site digital bridge.
CC Control Channel. The diagnostic interface between an NMS and the SDU.
CCITT Consultative Committee on International Telegraphy and Telephony. An advisory committee established
by the United Nations to recommend communications standards and policies. See ITU-TSS.
channel A bidirectional DS0, voice, or data path, for electrical transmission between two or more points. Also
called a circuit, link, path, or facility.
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