Description of the problem

At a site, OSN3500 equipment SSN3SL16 single board is interfaced with third-party equipment, and at a certain time, the third-party equipment reports HP_RDI alarm, and the service is interrupted. The third-party equipment reported HP_RDI alarm and the NGSDH equipment reported HP_TIM alarm, and the alarm times coincided.

Processing

First according to the third-party device business interruption cause is because of the receipt of HP_RDI, this device that is considered business interruption. The next step is to analyze the cause of HP_RDI. By analyzing the HP_RDI and HP_TIM alarm start time is the same, so we judge that this HP_RDI is HP_TIM back to the transmission. Then we analyze the reason of HP_TIM generation, according to the principle of HP_TIM generation, that is, the inconsistency between actual received J1 and receivable J1. We queried the actual received J1 is indeed different from the receivable J1. Therefore it is reasonable to report HP_TIM. The actual J1 bytes received were sent by the third party equipment, so we need the third party equipment to locate why the J1 bytes sent have changed. After coordinating with the other party's engineer, it was confirmed that the other party's equipment had made configuration changes.

Root cause

The root cause of the problem is a change in the J1 byte sent by the third-party device, which causes the NGSDH device to report HP_TIM and thus back to HP_RDI, resulting in a service interruption.

Solution Measures:

Modify the J1 byte sent by the third party device to be consistent with the J1 byte receivable by the NGSDH device.

Recommendation and Summary

The HP_TIM return of HP_RDI alarms is in line with the standard recommendations. Therefore the existing network needs to ensure that there are no HP_TIM alarms to avoid perceived service interruptions by third party devices.

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