Glossary
Glossary-3
3170-A2-GB20-20
December 1996
CRC6
CRC using six check bits.
CSA
Canadian Standards Association.
CSU
Channel Service Unit. Protects the E1 line from damage and regenerates the E1
signal.
Ctrl branch
Control branch of the E1 DSU/CSU menu tree.
CTS
Clear-to-Send. V.24 circuit 106.
Cust1
Customer 1 configuration area. The first of two sets of customer-defined
configuration options.
Cust2
Customer 2 configuration area. The second of two sets of customer-defined
configuration options.
DACS
Digital Access and Cross-connect System. A device that allows DS0 channels to be
individually rerouted and reconfigured.
daisy chaining
Connecting the COM port of one E1 DSU/CSU to the AUX port of another E1
DSU/CSU to provide SNMP connectivity.
database
An organized compilation of computerized data.
data port
The electrical interface between the E1 DSU/CSU and the synchronous data
terminal equipment.
DB15 connector
A 15-position connector used on cables or devices.
DB25 connector
A 25-position connector used on cables or devices.
DCE
Data Circuit-terminating Equipment or Data Communications Equipment. A device
which provides signal conversion for communication between the DTE and the
network.
DCLB
Data Channel Loopback. Loops the data received from the network interface, for all
DS0 channels allocated to the selected port, back to the network.
default
A preset value that is assumed to be correct unless changed by the user.
DevFail
Device Failure. A message that indicates that an internal failure has been detected
by the operating firmware. An 8-digit code appears for use by service personnel.
DevHS branch
Device Health and Status branch of the E1 DSU/CSU menu tree.
device
A mechanical, electrical, or electronic unit with a special purpose.
digital signal
A signal composed of discrete elements (zeros and ones) instead of a great
multitude of analog elements.
diskette
A thin, flexible magnetic disk enclose in a protective jacket.
DLB
DTE Loopback. Loops the received signal on the DTE Drop/Insert port back to the
DTE without change.
DL branch
Download branch of the E1 DSU/CSU menu tree.
download
A process that transfers device firmware from a locally-attached PC to a device, or
allows the duplication of firmware from a local device to a remote device.
downstream device
A device that is connected farther from the host computer.
drop/insert
An interconnection point for terminals, multiplexers, and transmission facilities.
Individual channels may be inserted into the aggregate stream or dropped out to
accommodate specific applications.
DSR
Data Set Ready. V.24 circuit 107.