Glossary
GL-2
9161-A2-GH30-20
September 1997
The transmission standard that specifies 12 frames as a superframe that is used for frame
synchronization and to locate signaling bits.
Excessive Error Rate.
End of Number.
Errored second. A second with one or more ESF error events (one or more CRC6 error
events or OOFs).
Electrostatic discharge.
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.
Federal Communications Commission.
Facility Data Link. The selected bits in the ESF format that are used for control, monitoring
and testing.
Foreign Exchange Office. An APM that extends voice channel connectivity to remote
switching equipment. The FXO interface appears as a telephone to the connecting
equipment.
Foreign Exchange Office Software-Defined Network.
Foreign Exchange Station. An APM that provides voice channel connectivity directly to
handsets or to PBX equipment.
Foreign Exchange Station Software-Defined Network.
Internet Control Management Protocol.
Internet Protocol. The TCP/IP standard protocol that defines the IP as a unit of information
passed across an Internet and provides the basis for packet delivery service. IP includes
the ICMP control and error message protocol as an integral part. The entire protocol suite
is often referred to as TCP/IP because TCP and IP are the two most fundamental
protocols.
I
nternational Telecommunication Union. Formerly known as the Consultive Committee on
International Telegraphy and Telephony.
Line Build-out. The amount of attenuation of the transmitted signal that is used to
compensate for the length of wire between the transmitter and the receiver.
Liquid Crystal Display.
Light Emitting Diode. A light or status indicator that glows in response to the presence of a
certain condition (e.g., ALM on the front panel for an alarm condition ).
Line Loopback. Loops the received signal on the network interface back to the network
without change.
Loss of Frame. Occurs when a DS1 terminal is unable to synchronize on the DS1 signal
for some interval (nominally 2 1/2 seconds).
Loss of Frame Count. A count of the number of LOFs declared.
Used to test various portions of a data link in order to isolate an equipment or data line
problem. A diagnostic procedure that sends a test message back to its origination point.
Loss of Signal. The T1 line condition where there are no pulses.
D4
EER
EON
ES
ESD
ESF
FCC
FDL
FXO
FXODN
FXS
FXSDN
ICMP
IP
ITU
LBO
LCD
LED
LLB
LOF
LOFC
loopback
LOS
