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Analysis Report on Failures to Create E2E Protection Groups for ASON NEs

Publication Date:  2012-07-25 Views:  3 Downloads:  0
Issue Description
After VC4 trails with SNCP protection are deactivated and then activated, the trails are activated but services on trails are interrupted.
A user performs the following operations:

1.Configures cross-connections in the NE Explorer.

2.Searches for trails based on the cross-connections on the network.

3.Deactivates the trails.The services are interrupted.

4.Activates the trails. The services are still interrupted. In normal conditions, services are restored after trails are activated.

5.Queries cross-connections on NEs.The selective receiving cross-connections of trails do not exist on NEs


Alarm Information
Null
Handling Process

Create cross-connections on NE Explorers and apply services by trail search.

When a problem occurred, restart the NMS and activate the service on the NE Explorer.


Root Cause

Cause analysis based on the NMS

1.The NMS needs to reallocate protection group IDs when the NMS activates trails for ASON NEs.

2.When SNCP and MSP 1+1 are configured, the NMS needs to reallocate protection relationship to differentiate working services from protection services.

3.Two protection groups (one working group and one protection group) associate with each other by using the working group ID as the associated protection group ID.

4.Cross-connections applied to NEs are generated by the sink and source information of the protection group in the working trail.

The NMS reallocates protection group IDs when trails are activated. However, the associated protection group ID in the database rather than in the memory is refreshed due to refreshing data failures. Therefore, the working and protection groups cannot associate with each other during service activation without the correct associated protection group ID. As a result, the working service is considered the protection service by mistake. The working services are not applied to NEs.

Cause analysis based on user operations

Failure to create E2E protection groups and restore services after reactivation
Protection group IDs are allocated when protection groups are created and are reallocated during trail activation. Therefore, the associated protection group ID is not successfully refreshed, the working service is considered the protection service by mistake and the working services are not successfully applied.

Suggestions
Install related patches to the NMS to fix the problem. The new patch is under developing.

END