Description of the problem

When engineers performed tuning and testing on PD3 channel, they found that the internal loopback alarm and A_LOC alarm were reported after the channel was looped back, while the service of loopback was not affected and the test was normal. The version of the network element is V1R6C02B012 (5.21.16.13).

Alarm Information

LOOP_ALM

A_LOC

Processing

Circumvention method:

In the case of a loopback, the software blocks the reporting of A_LOC alarms. ...

Fundamental solution:

The new version of the problematic veneer will software block the reporting of A_LOC alarms in the case of loopback. Upgrading to V1R6C02B014 (5.XX.16.14) and subsequent versions can completely solve this problem.

Root Cause

The A_LOC alarm indicates that the clock is lost, and it is confirmed that there is no signal access to the electrical port of the channel for loopback. As the external electrical port is suspended, the single-board chip cannot detect the clock, and A_LOC will be generated. Since the electrical port T_ALOS alarm exists before the loopback, the LOS alarm will inhibit the A_LOC, so the A_LOC alarm will not be reported; after setting the inner loop of the single-board, the software will only mask the LOS of the dropped port, so that there will be an A_LOC alarm reported.

Suggestion and Summary

The following branch circuit veneers all have this problem:

Huawei SSN2PQ3/SSN2PD3/SSN2PL3/SSN2PL3A/SSN1PD3/SSN1PL3/SSN1PL3A

The related technical information in this chapter and the troubleshooting process of SDH equipment are collected and organized by Shenzhen Optical Transmission Network Technology Company Limited (www.opticaltrans.com), please retain the reproduction! Our company specializes in Huawei SDH optical transmission equipment,SDH transmission equipment sales.