Administrator's Guide

L
Issue 5 October 2002 1979555-233-506
LBO
Line buildout
LDN
Listed directory number
LDS
Long-distance service
LEC
Local exchange carrier
LED
See light-emitting diode (LED).
light-emitting diode (LED)
A semiconductor device that produces light when voltage is applied. LEDs provide a visual indication of the
operational status of hardware components, the results of maintenance tests, the alarm status of circuit packs,
and the activation of telephone features.
lightwave transceiver
Hardware that provides an interface to fiber-optic cable from port circuit packs and DS1 converter circuit
packs. Lightwave transceivers convert electrical signals to light signals and vice versa.
line
A transmission path between a communications system or CO switching system and a voice terminal or other
terminal.
line appearance
See appearance.
line buildout
A selectable output attenuation is generally required of DTE equipment because T1 circuits require the last
span to lose 15–22.5 dB.
line port
Hardware that provides the access point to a communications system for each circuit associated with a tele-
phone or data terminal.
link
A transmitter-receiver channel that connects two systems.
link-access procedure on the D-channel (LAPD)
A link-layer protocol on the ISDN-BRI and ISDN-PRI data-link layer (level 2). LAPD provides data transfer
between two devices, and error and flow control on multiple logical links. LAPD is used for signaling and
low-speed packet data (X.25 and mode 3) on the signaling (D-) channel and for mode-3 data communications
on a bearer (B-) channel.
LINL
Local indirect neighbor link
local area network (LAN)
A networking arrangement designed for a limited geographical area. Generally, a LAN is limited in range to a
maximum of 6.2 miles and provides high-speed carrier service with low error rates. Common configurations
include daisy chain, star (including circuit-switched), ring, and bus.
logical link
The communications path between a processor and a BRI terminal.