When the OptiX OSN 1500 device interfaces with the 155M optical port of the router, the 2M service reports the LP_RDI alarm, which is analyzed and found to be due to the high-order overhead of the line board being in the pass-through state, which leads to the interruption of the low-order service. Therefore, when changing from high-order service to low-order service, you need to set the overhead mode correctly.

Products involved

Huawei SDH Equipment OptiX OSN1500

Failure Category

The device fails to interface with the router service, resulting in routing failure. Business interruption, LP_RDI

Phenomenon Description

When the network is expanded and remodeled, the SLQ1 single board of the OptiX OSN 1500 equipment is directly docked with the router optical card of Company C. The network is protected by 1+1 linear multiplexing segments. The network is protected by 1+1 linear multiplexing segments, with 2M services at one end and 155M optical port services docked at the other end, in which 2M services report LP_RDI alarms.

Cause Analysis

Check the optical transmission path, time slot docking, router hardware, and SDH single board overhead mode one by one to troubleshoot the problem.

Operation Steps

After the physical connection is normal, the SLQ1 board and the optical ports of Company C receive normal optical power, and there is no optical power alarm at the receiving end, but the link status of Company C's router shows down.

Querying the alarms, it is found that there is no abnormal alarm on the SLQ1 board, but the 2M service at the other end reports the LP_RDI alarm.

Loop back internally to the docking optical port of the SLQ1 single board, and the LP_RDI alarm of the 2M service disappears, indicating that the optical transmission path is normal.

The link status of Company C's router shows up on the docking optical port of the outer loop back to SLQ1 single board, so it is suspected that the time slot is incorrectly docked.

Check the first VC-12 in VC-4 of the SLQ1 single board to see that it is also the first VC-12 in Company C. Corresponding to the 2nd VC-12 of Company C, add a 2M service on the 22nd VC-12, and the remote 2M service still reports LP_RDI alarm, suspecting that the local end fails to receive optical signals.

Reset the router, and the fault remains after reboot.

Check the SDH service configuration. The docking optical port of the SLQ1 board at this end was originally a VC-4 service, and after deleting the VC-4 service, a new VC-12 service is added, and the overhead mode should be "Termination". Query the corresponding overhead mode, and it is still "pass-through". After setting it to "Termination", the LP_RDI alarm disappears and the service is normal.

References

When configuring a low-order service, the high-order overhead of the board must be set to "Terminate", otherwise the service will be interrupted.