Description of the problem

A customer at a site reflects that 2-second AU_AIS alarms are reported on some network elements passing through the OSN3500 multiplexing section after the service is reversed, and asks for an explanation of the reason for the 2-second AU_AIS.

Processing

First, analyze whether the multiplexed segment inversion is normal or not, by analyzing the k-byte events, all the page switching of the multiplexed segment ring are

are completed within 1 second. Moreover, only some of the network elements on the same service reported the alarm. Therefore, the first suspicion is that

that the differences in the alarm detection mechanism between network elements caused the different alarms to be reported.

Query the alarm filtering status of each network element:

Query results for network elements reporting 2-second AU_AIS alarms:

:alm-get-condetect

ALM-CONTINUOUS-STATE

CONTINUOUS STATE

disable

Total records :1

#9-315:szhw [PH_ROAD1][][2011-11-05 14:06:55+00:00]>

Query results for other network elements with unreported alarms for the same service:

:alm-get-condetect

ALM-CONTINUOUS-STATE

CONTINUOUS STATE

enable

Total records :1

#9-316:szhw [PH_ROAD2][][2011-11-05 14:08:21+00:00]>

The above query results indicate that the network element reporting an alarm does not have alarm filtering turned on, and when an alarm within 50ms is generated, the

When an alarm is generated within 50ms, the device will report AU_AIS for 2 seconds, but when alarm filtering is enabled, the AU_AIS for 50ms will be filtered.

will be filtered out and will not be displayed.

Root Cause

The root cause of the problem is that the alarm filtering is not enabled, resulting in an AU_AIS alarm within 50ms when the multiplexing segment is inverted, which is displayed as 2 seconds.

Solution

Emergency recovery measures:

None

Complete resolution measure: Enable alarm filtering.

Recommendations and summary

Alarm filtering is enabled by default in NGSHD devices, and it is recommended not to disable this function so as not to affect the problem localization.

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