Glossary
Issue 3 June 2000
GL-15
OSI
Open Systems Interconnection — Referring to the OSI reference model, a logical structure for net-
work operations standardized by the International Standards Organization (ISO).
OSGNE
Operations System Gateway Network Element — An OSGNE serves as a single interface to the OS
for NEs in the same subnetwork using X.25 interfaces.
OSP
Outside Plant
P
Pass Through
Paths that are cross-connected directly across an intermediate node in a ring network.
P-bit
Performance Bit
PC
Personal Computer
PCU
Power Converter Unit
PID
Program Identification
PINFET
Positive Intrinsic Negative Field Effect Transistor
PJC
Pointer Justification Count
Plesiochronous Network
A network that contains multiple maintenance subnetworks, each internally synchronous and all
operating at the same nominal frequency, but whose timing may be slightly different at any particu-
lar instant. For example in SONET networks, each timing traceable to their own Stratum 1 clock are
considered plesiochronous with respect to each other.
PLL
Phased-Locked Loop
PM
Performance Monitoring — Measures the quality of service and identifies degrading or marginally
operating systems (before an alarm would be generated).
PMN
Power Minor Alarm
POH
Path Overhead
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