Lightguide Cross-Connect (LGX)
A SONET device that contains ports for optical fiber connections to an optical network element
(NE). An LGX is used to make and change connections to an NE without changing the cabling
on the NE itself.
Line
A transmission medium, together with the associated equipment, required to provide the means
of transporting information between two consecutive network elements. One network element
originates the line signal; the other terminates it.
Line Timing
The capability to directly derive clock timing from an incoming OC-N signal while providing
theuser the capability to provision whether switching to an alternate OC-N from a different
source (as opposed to entering holdover) will occur if the OC-N currently used as the timing
reference for that NE becomes unsuitable as a reference. For example, intermediate nodes in a
linear network are line timed. See Loop Timing.
Local
See Near-End.
Local Area Network (LAN)
A communications network that covers a limited geographic area, is privately owned and user
administered, is mostly used for internal transfer of information within a business, is normally
contained within a single building or adjacent group of buildings, and transmits data at a very
rapid speed.
Locked DSn Cross-Connections
Locked DSn cross-connections add/drop traffic to/from only one rotation of a UPSR. Path
switching is disabled. Timeslots can be reused at different nodes around the UPSR.
LOF
Loss of Frame
Long Reach (LR)
A term used to describe distances of 40 km or more between optical transmitter and reciever
without regeneration. See Intermediate Reach.
Loopback
Type of diagnostic test used to compare an original transmitted signal with the resulting
received signal. A loopback is established when the received optical or electrical external
transmission signal is sent from a port or tributary input directly back toward the output.
LOP
Loss of Pointer
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G L O S S A R Y
G L - 1 4
Lucent Technologies
365-372-333 R2.1
Issue 4, June 2005
