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In the Uni-MSP ring configuration the service is interrupted after fiber broken.

Publication Date:  2019-07-03 Views:  142 Downloads:  0

Issue Description

In the Uni-Msp ring configuration which consist of 5 NE (155/622H) . Initially the service is normal after configuration. But after fiber is broken, the service is interrupted with RLOS and RLOF alarm.Then the service suddenly restore back after 10 minutes.

Alarm Information


Handling Process

Check the fiber connection and payload configuration 2. query with command line the protection switching state 3. Troubleshoot configuration file one by one to make sure every parameter are set correctly

Root Cause

After thorough analysis it is proven that the fiber connection and payload configuration is normal. It is found that at the Tu parameter setting in configuration is 75o&p. The Tu parameter is in the protection parameter. It should be set to np&75o .Although the TU do not play a part in the Uni- MSP protection it still affect because when the Protection mode shift from main to standby direction it found no back up in- service buses , thus triggering TU-AIS and interrupt the service. The service only recovered after 10 minutes when the protection switching from standby to main occurs


The command line parameter setting is very important in the MSP protocol switching. Therefore all the parameter should be follow closely in order to make the MSP protection switching really works , even the unsuspecting parameter like the TU parameter should be paid attention