ADTRAN 1200212L1, User Manual

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Appendix D. Glossary
61200212L1-1 DSU IQ User Manual D-3
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 trans-
mission 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 com-
pany 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 compa-
nies.
data link connection identifier (DLCI)
A unique number assigned to a PVC end point in a frame relay network. Identi-
fies a particular PVC endpoint within a user's access channel in a frame relay
network and has local significance only to that channel.
discard eligibility (DE)
A user-set bit indicating that a frame may be discarded in preference to other
frames if congestion occurs, to maintain the committed quality of service within
the network. Frames with the DE bit set are considered Be excess data.