Glossary
GL-4
Cisco uBR10012 Universal Broadband Router Hardware Installation Guide
78-11450-03 Rev.B0
CO Central office. The local telephone company office to which all local loops in a given area connect and
in which circuit switching of subscriber lines occurs.
Command Line
Interface
See CLI.
Console Data terminal equipment (DTE) through which commands are entered into a host.
Critical alarm An alarm condition that might affect most or all subscribers that connect to the reporting node. To
obtain more information about a problem, use the
show facility-alarm status command. See also Major alarm and Minor alarm.
D
Data terminal
equipment
See DTE.
DCE Data circuit-terminating equipment (ITU-T expansion). Devices and connections of a communications
network that comprise the network end of the user-to-network interface. The DCE provides a physical
connection to the network, forwards traffic, and provides a clocking signal used to synchronize data
transmission between DCE and DTE devices. Modems and interface cards are examples of DCE.
Compare with DTE.
DRAM Dynamic random access memory. RAM that stores information in capacitors that must be periodically
refreshed. Delays can occur because DRAMs are inaccessible to the processor when refreshing their
contents. However, DRAMs are less complex and have greater capacity than SRAMs. See also SRAM.
DS0 Digital signal level 0. Framing specification used in transmitting digital signals over a single channel
at 64 kbps on a T1 facility. Compare with DS1 and DS3.
DS1 Digital signal level 1. Framing specification used in transmitting digital signals at 1.544Mbps on a T1
facility (in the United States) or at 2.108Mbps on an E1 facility (in Europe). Compare with DS0 and
DS3.
DS3 Digital signal level 3. Framing specification used for transmitting digital signals at 44.736 Mbps on a
T3 facility. Compare with DS0 and DS1.
DSU Data Service Unit. Device used in digital transmission that adapts the physical interface on a DTE
device to a transmission facility such as T1 or E1. The DSU is also responsible for such functions as
signal timing. Often used with CSU, as in CSU/DSU.
DTE Data terminal equipment. Device at the user end of a user-network interface that serves as a data source,
destination, or both. DTE connects to a data network through a DCE device (for example, a modem)
and typically uses clocking signals generated by the DCE. DTE includes devices such as computers,
protocol translators, and multiplexers.
Dynamic random
access memory
See DRAM.