Description of the problem

After an ASON network element in the ASON bureau of Huawei OSN3500 equipment was abnormally powered down, several intelligent services were interrupted, and the intelligent services reported the "CP_SER_INT" control level alarm, and the rerouting failure event was recorded in the abnormal events of the network management, with the error code: 40497, and the services were resumed only after the power-down network element was re-powered. The service is resumed only after the power down network element is re-powered.

Processing

1) After checking, the interrupted smart service is a silver-level circuit service, which walks on the multiplexing segment working resources before interruption, while the smart service passes through two tangent multiplexing segment rings, and the power-down node is exactly the tangent node, as shown in the following figure:

2) Alarm "CP_SER_INT" is an alarm reported by the intelligent control level after detecting that the intelligent service has been interrupted. Error code 40497 of the rerouting failure event indicates that the rerouting route has failed, but the checking reveals that on the right side of the two tangent loops (as shown in the figure above), there are still free resources, and the service will not be interrupted if it is rerouted to these free resources. If the service is rerouted to these free resources, the service will not be interrupted.

3) However, on the right side of the two tangent rings, the multiplexing segment protection resources cannot be used because the network elements are in the inverted state when they are powered down. And the work resource cannot be used because the intelligent silver-level service rerouting specification does not support it. Therefore, in the end, these silver-level intelligent circuit service reroutes fail to report route counting because there are no resources available.

4) However, if these silver-level intelligent circuits are configured as gold-level types, the work resources on the right side of the two tangent loops can be used by the gold-level services during the rerouting, and the rerouting will be successful.

Root Cause

Incorrect selection of SLAs for smart service protection types leads to eventual re-routing failures and service interruptions for smart services.

Solution

Modify the protection type SLA of the intelligent services of Huawei OSN3500 devices from silver to gold, and the problem of the above scenario is solved.

Recommendations and Summary

For the selection of intelligent service SLAs, it is important to select the correct type of intelligent protection based on the SLA requirements of the bearer service, network topology, and other factors in a comprehensive manner.

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