Service interruption occurs because of a channel rate mismatch between TN54NS3 boards on the OptiX OSN 8800 and OSN 6800 network.
Fault Symptom
At a site of an OptiX OSN 8800 network in country T, a service is interrupted after it is switched to the protection path upon a fiber cut on the working path.
Cause Analysis
The TN54NS3 boards at the sites A and B on the faulty link use the standard ODU2 mode, but the interconnected TN54NS3 boards at sites C and D use ODU2 speedup mode. The inconsistency in the ODU2 rate modes of the NS3 boards results in the service interruption.
Procedure
- Browse alarms on every NE on the link. No unexpected alarms are present.
- Confirm that the service type is 10GE LAN and the port mapping mode is MAC transparent transmission.
- Obtain service cross-connections from the frontline engineer, as listed below.
- Confirm with the frontline engineer, learning that the ODU2 rate modes are displayed as standard ODU2 mode for the TN54NS3 boards.
- Confirm that the frontline engineer has changed the service channels. The service is restored after the service channels are changed. The highlighted channels in the following table are the new channels.
- Upload the data of all the NEs to the U2000 and query the channel rate modes of all the TN54NS3 boards. It is observed that the TN54NS3 board in slot 31 at site C and that in slot 17 at site D are provisioned with the ODU2 speedup mode. The mismatch of the ODU2 rate modes between the TN54NS3 boards leads to the service interruption.
Conclusion and Suggestion
Before deploying a service on a link, use the U2000 to query the channel data rate modes of the NEs on the link. To ensure that the NE data on the U2000 is consistent with that on the NEs, upload the data of all NEs on the link to the U2000 before performing the query.
If a service with a data rate less than the service rate of line boards is interrupted on a live network but no abnormal alarm is found, enable non-intrusive monitoring for the line boards section by section. Using the OptiX OSN 8800 network in country T as an example, the TN54NS3 boards in slot 31 at site C is interconnected with the TN54NS3 board in slot 17 at site D and the ODU2 speedup mode is specified for the ODU2LP1-1 channels on the two boards. However, the ODU2LP1-1 channels from the upstream sites are in standard ODU2 mode. When non-intrusive monitoring is enabled, an ODU2_PM_SSF alarm can be reported for the TN54NS3 board in slot 17 at site B.
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