Description of the problem

The customer feedbacks that the existing network is configured with MSP and SNCP protection, and when the fiber is cut off, there is instantaneous cut off phenomenon from the view of the final wireless side service, and it is necessary to analyze the root cause and solution;

The specific fiber break time points are as follows:

A-B (working link)

20/11/2014 09:42:04

20/11/2014 12:12:38

02:30:34

A-C (protection link)

20/11/2014 10:43:30

20/11/2014 10:43:36

00:00:06

20/11/2014 10:51:41

20/11/2014 11:14:08

00:22:27

Processing

Step 1

On November 20, fiber breakage occurs in both directions on working links A and B, and a multiplexing segment inversion occurs, and a multiplexing segment inversion alarm is retuned (the point in time of the failure is November 20, and the K bytes have been bypassed when the information is collected on November 28, and the earliest K byte information is on November 24th.

Alarm at station A:

981543 8 r_lof cr end 2014-11-20 09:42:04 2014-11-20 12:05:00 0x01 0x00 0x01 0xff 0xff

981554 10 MS_APS_INDI_EX MJ end 2014-11-20 09:42:04 2014-11-20 10:43:30 0x02 0x01 0x08 0x01 0x00

981816 10 MS_APS_INDI_EX MJ end 2014-11-20 10:43:34 2014-11-20 10:51:41 0x02 0x01 0x08 0x01 0x00

982072 10 MS_APS_INDI_EX MJ end 2014-11-20 11:21:27 2014-11-20 11:24:02 0x02 0x01 0x08 0x01 0x00

982129 10 MS_APS_INDI_EX MJ end 2014-11-20 11:24:06 2014-11-20 12:22:37 0x02 0x01 0x08 0x01 0x00

B station alert:

716270 11 R_LOF CR end 2014-11-20 09:42:06 2014-11-20 12:12:36 0x01 0x00 0x01 0xff 0xff

716167 10 MS_APS_INDI_EX MJ end 2014-11-20 09:42:05 2014-11-20 12:22:38 0x02 0x01 0x0b 0x01 0x00

Step 2

The configuration situation is sorted out, the MSP multiplexing segment is a 5-point ring, and these two 3500 devices are for nodes 0 and 4. The corresponding service path is a data service, and the non-recoverable low-order SNCP service is configured at nodes A and B. The MSP multiplexing segment is a 5-point ring, and the two 3500 devices are nodes 0 and 4.

Station A:

#0x1001d:cfg-get-rmsbdmap:1;.

MSSPR-PU-MAP

pg-id pu-id board-id port-id au4-map

1 west1 8 1 1&&8

1 east1 11 1 1&&8

#0x1001d:cfg-get-sncpbdmap:18;

SNCP-PU-MAP

PG-ID PU-ID SRC-BID SRC-PID SRC-AU4 SRC-PATH DST-BID DST-PID DST-AU4 DST-PATH XC-LEVEL

18 work 8 1 5 3 5 1 10 1 vc3

18 backup 8 4 1 3 5 1 10 1 vc3

Station B:

#0x1001e:cfg-get-rmsbdmap:1.

MSSPR-PU-MAP

pg-id pu-id board-id port-id au4-map

1 west1 8 1 1&&8

1 east1 11 1 1&&8

#0x1001e:cfg-get-sncpbdmap:18;

SNCP-PU-MAP

PG-ID PU-ID SRC-BID SRC-PID SRC-AU4 SRC-PATH DST-BID DST-PID DST-AU4 DST-PATH XC-LEVEL

18 work 11 1 5 3 16 1 5 1 vc3

18 backup 8 4 1 3 16 1 5 1 vc3

Step 3

The service alarms corresponding to the reversal of the multiplexed segments only flash off during the reversal of the multiplexed segments, which is a normal situation, and no long-time abnormality is found.

Station A:

981628 5 TU_AIS_VC3 MJ end 2014-11-20 09:42:05 2014-11-20 09:42:06 0x01 0x00 0x1c 0xff 0xff

981634 5 ALM_GFP_dLFD MJ end 2014-11-20 09:42:06 2014-11-20 09:42:09 0x01 0x00 0x06 0xff 0xff

Station B:

716278 16 TU_AIS_VC3 MJ end 2014-11-20 09:42:05 2014-11-20 09:42:09 0x01 0x00 0x0d 0xff 0xff

Step 4

From the crossboard black box records, no anomalies were found during this time period.

Step 5

Check the SNCP unit inversion delay time for the multiplexing segment MSP and find that it is not set.

Root Cause

SNCP and MSP inversion overlay leads to instantaneous service disconnection after fiber break.

Solution

Set the delay time of SNCP inversion for the multiplexing segment to avoid mutual influence and cause multiple inversions resulting in instantaneous business interruption, the screenshot of the network management settings is as follows:

Recommendationsand Summary

1. Try to conduct inversion tests in the faulty sections of A and B (board 8 of A and board 11 of B) to observe the service interruption on the wireless side, and contact Huawei in a timely manner to define the problematic fault points if abnormalities are found in the wireless equipment;

2. Conduct regular inspections of the network to identify potential problems in advance;

3. It is recommended that you enable the alarm filtering function: alm-set-condetect:enable on the A network element.

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 the reproduction! Our company specializes in the sales of Huawei SDH optical transmission equipment,SDH transmission equipment.