Description of the problem

The lower service point of a low-order SNCP ring is configured on a node of a ring-multiplexed segment ring, and the SNCP service is configured on the working channel of the ring-multiplexed segment ring, but the protection of this SNCP is not configured on the ring-multiplexed segment ring. The service point on the working channel of this low-order SNCP service is connected to another site of the ring multiplexing segment, and a power failure at this site causes the multiplexing segment ring to be inverted, and then the low-order SNCP service is interrupted, but there are no alarms for this low-order SNCP service.

Processing

First, check whether the inversion of this multiplexing segment is successful, and then query the K-byte events of the whole ring and the inversion page to see whether the inversion is successful.

By querying the K-byte events and the page switching situation of the whole ring, the page switching is correct at the power-down point and the stations at both ends, and all other stations on the ring have entered the pass-through page correctly, which indicates that the rewinding of the multiplexing segment is correct.

Then check whether the reversal event of the SNCP where the interrupted service is located is correct, and find that there is no reversal event generated by this SNCP at the point of time of power down, indicating that this SNCP has been working in the working channel, and because the working channel of this SNCP has already been selected in the protection channel of the multiplexing segment due to the reversal of multiplexing segments, and because the corresponding channels of the reversed site of the multiplexing segment ring have been configured with the service, thus the misconnection occurs, resulting in the low-power segment. A misconnection occurs, resulting in a low-order SNCP service interruption without an alarm.

Root Cause

The root cause of this issue is that the service is misconnected when the service point on the SNCP is powered down, resulting in service interruption without alarm.

Solution

Emergency recovery measures: Forcibly switch SNCP to the protected channel.

Complete solution: Configure the protection of SNCP on the ring of multiplexed segments and configure it as recoverable.

Recommendations and Summary

Low-order jobs are configured on the multiplexed segment ring, and misconnections cannot be avoided. When low-order SNCP is coupled with MSPs, it is recommended that SNCP jobs not be configured on the multiplexed segment ring.

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