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Similarity problem with Nokia Netact CRB AM
This document has not been formally reviewed for accuracy and is provided as is
Title :
Similarity problem with Nokia Netact CRB AM
Document ID :
KM01191203
Product - Version:
temip access module library ;
OS :
Updated :
Wed Oct 01 08:23:00 GMT 2014
Summary :
Similar alarm problem can be faced with Nokia Netact CRB AM with similarity applied on the OC in case of no NotificationID. Similarity doesn't work since SpecificProblem attribute is unique in according to Nokia Netact mapping rules.

The following similar alarm problem can be faced with Nokia Netact CRB AM (CRB52I-NNET520-Level4-RevA) with similarity applied on the OC:

Reduction Mode = Automatic
Similarity Mode = SameProblemType
Reduction Scope = NotTerminatedAO

In according to TeMIP documenation in case of no Notification ID similarity is based on Managed Object, Probable Cause, Alarm Type, and Specific Problem.
But in according to Nokia Netact maping rules SpecificProblem attribute is unique, so similarity doesn't work properly.

Solution

Unfortunately there is no possibility to apply it to make similarity/clear correlation work properly.

In Nokia Netact CRB AM TeMIP Specific Problem is mapped from alarmId value, which uniquely identifies alarms. So TeMIP SP is unique setOf Unsigned32 and it doesn’t allow to make similar alarms based on the same MO, AT, PC, SP.
To allow it TeMIP SP should be mapped from Original SP.
But in this case clear correlation will not work properly since clear correlation is defined by the same alarmId value, which was in TeMIP SP before.
In according to Netact NBI FS 3.3.11 Notification about the clearing of an alarm:
“On NBI, the correlation between the original (new) alarm and the cleared alarm is defined by the same alarmId value.”

So it’s needed to set NotificationId/CorrelatedNotifId fields from alarmId value to make clear correlation work properly.

After investigation unfortunately it will not work properly in all cases. Foe example at the following scenario:

1. Suppose we have original alarm with 3 similar alarms. Each alarm has its own NotificationId, mapped from alarmId, and the same MO, SP, PC, AT.
2. Clear alarm correlated to original one has come (correlatedNotifId of clear alarm equals to NotificationId of original one).
3. Original alarm is cleared. Clearance Report Flag attribute of original alarm is set to True.
4. Then new similar alarm has come.
5. Clearance Report Flag is set again to False in according to Alarm Handling manual 1.6.1:
“The Clearance flag is removed, if a new incoming alarm is created as a Similar Alarm of this Original Alarm Object”.
6. It looks like this original alarm will never be cleared since clear for this alarm has already been sent and clears for similar alarms cannot clear it (they results as orphaned clear alarms).

So as a result we can have many not cleared alarms which are actually cleared.

Unfortunately CF creation will not help also since it copies above mapping changes and will have the same consequence.

If there is such possiblity to make similarity on EMS side, it can be possible solution.