Appendix D - Glossary
150-359-100-01, Revision 01
58
October 27, 2000
HXU-359 List 1
NE
Network Element — Any device that is part of a SONET
transmission path and serves one or more of the section, line,
and path-terminating functions.
NI
Network Interface
NID
Network Interface Device
NMA
Network Management and Administration
NRZ
Non-Return to Zero — An E1 line code.
NVRAM
Non-Volatile Random Access Memory
OC-3
Optical Carrier Level 3 — The optical equivalent of an STS-1
signal.
OOF
Out of Frame — An OOF occurs when four or five consecutive
SONET frames are received with errored framing patterns. The
OOF state clears when two consecutive SONET frames are
received with valid framing patterns.
OOS-A
Out Of Service — Administration
OOS-M
Out of Service — Maintenance
Overhead
Extra bits in a digital stream used to carry information besides
traffic signals.
Path
A logical connection between a point where an STS or VT is
multiplexed to the point where it is demultiplexed.
Path Trace
A user-defined value that is passed through the SONET
network as a test pattern to validate path integrity.
PBX
Private Branch Exchange - Private local voice switching
PM
Performance Monitoring
RCV
Receive
RDI
Remote Defect Indication — A signal returned to the
transmitting terminating equipment upon detecting a LOS, LOF
or AIS defect.
REI
Remote Error Indication — An indication returned to a
transmitting node (source) that an errored block has been
detected at the receiving node (sink). Also know as a Far-end
Block Error.