Glossary
GL-4 3162-A2-GB20-30
March 1999
Data Set Ready. A signal from the modem to the DTE that indicates the modem is turned
ON and connected to the DTE.
Data Service Unit. Data communications equipment that provides timing, signal
regeneration, and an interface to data terminal equipment. A subrate DSU/CSU is normally
referred to as a DSU.
Digital Signal Cross Connect level 1. An interconnection point for terminals, multiplexers
and transmission facilities.
Data Terminal Equipment. The equipment, such as a computer or terminal, that provides
data in the form of digital signals for transmission.
The DTE interface on the rear panel of the CSU.
Dual-Tone Multi-Frequency. A signaling method using two voice frequencies to designate
the tones used for touch-tone dialing, as distinguished from pulse dialing.
Data Terminal Ready. A signal from the DTE to the modem, sent via Pin 20 of the
EIA-232 interface (V.24 circuit 108/1, /2), that indicates the DTE is turned ON and
connected to the modem.
A wideband digital interface operating at 2.048 Mbps, defined by ITU recommendations
G.703 and G.704. It is used primarily outside North America.
Excessive Error Rate. An error rate that is greater than the threshold that has been
configured in the device.
MIB objects unique to a specific company’s devices.
A trap unique to a specific company’s devices.
End of Number.
A discrepancy between a measured or computed value or condition and the true or
specified value or condition.
Errored Seconds. A second with one or more ESF error events (one or more CRC6 error
events or OOFs).
ElectroStatic Discharge. An undesirable discharge of static electricity that can damage
equipment and degrade electrical circuitry.
Extended SuperFrame. The T1 transmission standard that specifies 24 frames as an
extended superframe to be used for frame synchronization and to locate signaling bits.
Factory 1 configuration area. The first of two configuration option sets that are preset at
the factory (read-only options).
Factory 2 configuration area. The first of two configuration option sets that are preset at
the factory (read-only options).
An uncorrected hardware error.
An accidental condition that causes a functional unit to fail to perform its required function.
Federal Communications Commission. The Board of Commissioners that regulates all
electrical communications that originate in the United States.
Facility Data Link. The selected framing bits in the ESF format used in a wide-area link that
are used for control, monitoring, and testing.
Individual DS0 channels that may be sold separately or in groups to provide bandwidth
that is some fraction of the total T1 capability.
DSR
DSU
DSX-1
DTE
DTE interface
DTMF
DTR
E1
EER
Enterprise MIB
enterprise-specific
trap
EON
error
ES
ESD
ESF
Fact1
Fact2
failure
fault
FCC
FDL
Fractional T1