Description of the problem

After SDH transmission equipment is configured with double-end-recovery Tunnel APS protection, when the working channel fiber is pulled (the effect of pulling a single fiber and a dual fiber is the same), 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 the waiting 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 home is related to the order of restoring the fiber, and the end that is restored after reception will enter WTR. the end that is restored after reception is restored first, and after reception is restored, because the entire APS has not been restored yet (the reception of the home node has to be restored to the APS to be restored), this end is already normal before the APS is restored to the APS, so the end that is restored to receive the fiber first will not enter WTR, but display Normal instead. enter the WTR, but rather display the Normal state.

Solution

Reconfigure.