Frame Relay Service Unit User Manual

61200.130L1-1 FSU User Manual 119
Glossary
CRC
Cyclic redundancy check. A computational means to ensure the accuracy of
frames transmitted between devices in a frame relay network. The mathematical
function is computed, before the frame is transmitted, at the originating device.
Its numerical value is computed based on the content of the frame. This value is
compared with a recomputed value of the function at the destination device. See
also frame check sequence (FCS).
CS
See CTS.
CSU
See Channel Service Unit.
CTS
Clear to send. A signal on the DTE interface indicating that the DCE is clear to
send data.
data service unit
DSU. A device designed to transmit and receive digital data on digital
transmission facilities.
dB
Decibel. A unit of measure of signal strength, usually the relation between a
transmitted signal and a standard signal source.
data communications equipment (DCE)
Device that provides all the functions required for connection to telephone
company lines and for converting signals between telephone lines and DTE.
Also see DTE.
DDS
digital data service. A private line digital service, for transmitting data end-to-
end at speeds of 2.4, 4.8, 9.6, and 56 kbps and in some cases 19.2, 38.4, or 64 kbps.
The systems can use central hub offices for obtaining test access, bridging legs of
multipoint circuits, and cross connecting equipment. DDS is offered on an inter-
LATA basis by AT&T and on an intra-LATA basis by the Bell operating
companies.