MG-IP TDM Over IP Gateway Reference Manual
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Failure Integration/Deintegration Time
Table 5 specifies integration/deintegration time in seconds for failure declaration and clearance.
Table 5: Failure Integration/deintegration Times (Sec)
Defect
Failures
Integration Time
(Sec)
Deintegration Time
(Sec)
Loss of Signal (LOS)
LOS (red)
2.5
10
Out of Frame (OOF)
LOF (red)
2.5
10
Remote Alarm Indication (RAI)
RAI (yellow)
0.5
0.5
Alarm Indication Signal (AIS)
AIS (blue)
2.5
10
Loss of Multi-frame (LOM)
LOMF (red)
0.0
10
Remote Alarm Indication (MRAI)
RLOMF
(yellow)
0.5 0.5
TS 16 Alarm Indication Signal (AIS)
AIS (blue)
2.5
10
PDH Fault Correlation
According to Bellcore/ITU-T requirements, any single failure (or root cause of incoming signal
problems) must result in a single alarm output message only. Non-traffic-related failures may be
exceptions to the "single failure/single message" criteria.
Fault correlation logic is a software filter that filters out all "non-root-causing problem" alarms and
relies on the fact that most alarms are related to each other and are organized hierarchicaly.
For the purpose of alarms reporting, traffic-related failures can be divided into Near-End (i.e. LOS,
LOF, AIS, etc.) and Far-End failures (i.e. RAI, RLOMF).
In general, the following rules need be applied:
Declaration of a failure will immediately clear any existing failure from a lower level. It
should also disable further declaration of any lower-level failure
Clearing of a failure will allow declaration of lower-level failures, if conditions warrant such
declaration
Table 6 defines the hierarchy of Near-End failures, while Table 7 defines the hierarchy of Far-End
failuresTable 8 defines the relations and hierarchy of both Near-End and Far-End failures.
To avoid reporting of multiple traps for a single event (as a result of numerous "correlation" actions),
simple stabilization logic can be implemented (for example, a trap sending routine can be scheduled to
accumulate alarms for periods of 100 milliseconds). This will avoid a typical scenario of a single LOS
clearance resulting in declaration and clearing of the LOF trap (inhibited by LOS).
Table 6: PDH Near-End Failure Hierarchy
Failure
Fault Correlation Action
LOS
“Declared” state will clear and inhibit declaration of all failures listed below.
“Cleared” state will enable declaration and declare all relevant failures listed below.
AIS
“Declared” state will clear and inhibit declaration of all failures listed below.
“Cleared” state will enable declaration and declare all relevant failures listed below.
LOF
“Declared” state will clear and inhibit declaration of all failures listed below.
“Cleared” state will enable declaration and declare all relevant failures listed below.