Diagnosis of external failure

When the Optical Transport Manager for PDH receives alarms that relate connections from network elements it manages to those it does not manage, special analysis is performed to determine if a problem has occurred in the connected network rather than in the managed network.

This additional analysis is performed for circuits that have a Down notification. The following alarms are used in determining the existence of an external failure. These alarms may be applied to CTPs at various rates (for example, VC12, VC11, E1).

• LOP on the aEnd or zEnd CTP

• AIS on the aEnd or zEnd CTP

• UNEQ on the aEnd or zEnd CTP

• TIM on the aEnd or zEnd CTP

• PLM on the aEnd or zEnd CTP

• PDI on the aEnd or zEnd CTP

• SSF on the aEnd or zEnd CTP

• HighOrder_Trail TrailDown and TrailAtRisk alarms where the failed end cannot be determined

  When analysis shows that an external failure has occurred, the UserDefined1 attribute is updated to show where the failure has occurred.

  The UserDefined1 attribute can take one of the following values:

• zEnd Customer Network - External Failure

• Service Provider Network - Internal Failure

• aEnd Customer Network - External Failure

• Customer Network - External Failure

  Customer Network - External Failure is a special case of DropSideTopologicalLink Down where the end location of the external failure cannot be determined.