Description of the problem

The MSP ring composed of Huawei's SDH transmission equipment OSN3500 is interrupted by a bureau due to fiber breakage occurring on the ring, resulting in the interruption of service between B-C. After the fiber cable is restored, the service is restored.

Alarm Information

APS_INDI, HP_UNEQ

Processing

1. Query the K-byte information of the inverted 2 points on the ring and find no abnormality;

2、Network management queried the ring information of the multiplexing section, and found that point C reported "protection status query failure", and queried with command line.

:cfg-get-rmsstate:1

Return: failed! cmd:0x852c error:0x9760 NSERR_BDRSP_BAD_PARA; it is suspected that the information of multiplexed segment at point C is lost.

3, consult the user, it has done the following operations at point C: point C can not configure the service, the bureau suspected that the GSCC failure, so replace the GSCC with a new one, the download data prompted download failure! The original GSCC was inserted to restore the original, but not downloaded.

As the master and single board communication under the configuration is realized through the AUX single board, then try to replace the AUX single board, can not configure the business problem is solved.

4, so suspect that this failure for the old master control back into the plug, due to the failure of the AUX veneer at that time, not all synchronization led to the loss of cross-side multiplexing segment node information, and subsequently did not download and verify the result. Configure the multiplexing segment parameters at point C, invert the test, and the problem is solved.

5. Since the calibration is done after the network management data is sent down to the GSCC, the multiplexing segment configuration is available on the host. The data on the cross-board is lost due to abnormal inter-board communication multiplexing segment configuration. The existing inspection use case only queries the multiplexing segment configuration on the host side.

However, the multiplexing segment protocol of the NGSDH product is moved down to the cross-board, and it is not possible to thoroughly inspect the network hazards by simply checking whether the multiplexing segment is configured on the host. Therefore, this problem cannot be found during the inspection.

Root Cause

The loss of multiplexing segment information on the intersection board at site C caused the failure. That is, although the K-byte pass-through of the dual optical board at site C enables the pre-inversion protocol to be processed normally, the intermediate pass-through site C is unable to process the K-byte due to the lack of a multiplexing segment configuration.

Thus, this site cannot enter the concatenation state, resulting in the last 8 vc4s not being able to establish concatenation, so the service is interrupted when the service is inverted to the last 8 protected vc4s. Analyzing the black box of the crossover board, it can be concluded that the failure of the multiplexing segment module in the crossover board leads to

Loss of multiplexing segment configuration. Since it is not a hardware failure, the master-standby inversion is not triggered.

Recommendations and Summary

1. It is recommended that the inspection tool add the multiplexed segment configuration query command of the cross-board to the inspection case as well;

2、Regularly query the multiplexing segment information on the network management protection view, or regularly urge the customer to carry out the reversal test.

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