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FAQ-Status Display of the OWSP and the ODUk SPRing Protection Protocol

Publication Date:  2012-07-25 Views:  76 Downloads:  0
Issue Description
In the ODUSP or the OWSP protection, an SF_RP failure is detected at end A of a service section. In the same service section, an SF_W failure is detected at end B. At this time, SF_R switching is performed in this section. When the SF_W failure is cleared at end B, the SF_R switching is still performed in this section. Why?
Note: This problem does not affect the switching, but it affects the status display of the protection group. 
Alarm Information
Handling Process
To understand the current implementation mode of the OWSP and the ODUk SPRing protection protocol:
The current implementation mode is partial recovery. When the SF occurs in both the working and protection channels, if the SF in only the working channel is cleared, the section still performs the SF_R switching. This is called partial recovery for the SF in only one channel is cleared.
As the short path of end B still receives the SF_P request from end A, end B keeps performing the SF_R switching. When the SF_R switching is performed at end B, regardless of the failure (SF_P or SF_RP) at end A, the short path of end A keeps sending the SF_P request. Therefore, when end B clears the SF_W, it maintains the SF_R, because it cannot determine whether the failure at end A is SF_P or SF_RP. 
Root Cause