Description of the problem

After the customer configures OSN3500 SDH equipment with double-end-recovery Tunnel APS protection, when pulling the fiber of the working channel (the effect of pulling a single fiber is the same as that of a dual fiber), the service is inverted to the protection channel, and at this time the working channel fiber is restored, and it is found that the inverted state of the source node and the host node of the APS is not the same (one is WTR, and the other one is Normal).

Processing

Reconfigure.

Root cause

WTR is waiting for the recovery state, that is, the equipment in order to prevent the protocol state jitter a design principle, mainly refers to the channel from bad to good need to go through a state, so also only happened to break the fiber recovery of the channel state will be WTR, and did not happen from bad to good process changes in the channel is not in this state. However, if both fibers are broken, the state of the APS's home state is related to the order of restoring the fibers, and the end that is restored after reception will enter WTR. the end that is restored first after reception is restored because the entire APS has not yet been restored (the reception of the home node has to be restored for the APS to be restored), so for the APS before the APS is restored this end has been normal, so the end that is restored first to receive the fibers does not enter WTR, but displays Normal. enter WTR, but rather show Normal state.

Solution

Reconfigure.

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