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Normal Switching Is Triggered Although Without the Alarms Triggering MSP Switching due to the Alarm Anti-Jitter Function

Publication Date:  2012-07-25 Views:  39 Downloads:  0
Issue Description
The transmit NE and the receive NE of the OSN report only the MS_RDI alarm but not the alarms that may trigger MSP switching, such as R_LOS, R_LOF, MS_AIS, or B2_OVER. MSP switching, however, occurs to the OSN equipment. The services are normally switched over. 
Alarm Information
Handling Process
1. Run the :alm-get-hisdata:0,0 command to query the history alarms. The query results are the same as the results of history alarm query in the T2000. Only the MS_RDI alarm is reported.
2. Query whether the alarms that may trigger MSP switching are shielded in the T2000. These alarms are not shielded.
3. Consult relevant documents: To reduce the alarms that are momentarily reported but are unnecessary, by default the anti-jitter function is set for all alarms. In general, the duration is set to three seconds, that is, an alarm is not reported if the alarm lasts for less than three seconds. The shortest time from the moment when the SF is detected in K bytes to the moment when the SF disappears is four seconds. Therefore, the MS_RDI alarm lasting for four seconds transmitted in K bytes is reported but the R_LOS, R_LOF, MS_AIS, and B2_OVER alarms are not reported as a result of the anti-jitter function set for these alarms. The root cause may be that the momentary interruption of the optical fiber causes a signal failure.
4. Run the :alm-get-condetect; command to query the alarm anti-jitter function of the NE. The query result is enable, indicating that the alarm anti-jitter function is enabled. This proves the previous inference.
5. The default time of the alarm anti-jitter function can be manually set through the command line (:alm-set-para:flag,vol1,vol2,vol3;, for instance :alm-set-para:9,0,10,0; sets the delay to 10 seconds).
6. You can also run the :alm-set-condetect:disable command to disable the alarm anti-jitter function. This, however, is not recommended, because plenty of momentary alarms will be reported to block the ECC channels and affect the T2000’s NE management. 
Root Cause
1. MSP switching condition: When an alarm such as R_LOS, R_LOF, MS_AIS, or B2_OVER is generated, the Signal Fail (SF) is detected in K bytes and then MPS switching is triggered. The MS_RDI alarm does not trigger MSP witching.
2. The above alarms are generated but not reported to the T2000.
3. The T2000 shields the above alarms.