Symptom
On a network built with the OptiX Metro 6100, two GE services are configured between sites A and B. The LQG board reports a CLIENT_SF alarm on the channel with abnormal services. The services are not configured with protection.
Check for the history alarms in the data sent back by field engineers and find that the LQG board at site A is interconnected with the LQG board at site B and the two LQG boards report the transient R_LOC alarms.
Cause analysis
The possible causes of the fault are as follows:
- The WDM system functions abnormally.
- The LQG boards are faulty.
- The clock source settings of the LQG boards are incorrect.
Procedure
- Check the network topology, and find that the other boards on the same route work normally and the receive and transmit optical power of the two interconnected LQG boards are proper. Thus, rule out the possibility that the WDM system is faulty.
- Query alarms on the two LQG boards and find that the boards report the transient R_LOC alarms for a long time. Then, query the clock source settings of the boards and find that two LQG boards are enabled to trace the line clock. See the following figure.
Reference Information
Conclusions and suggestions for this case are as follows:
The WDM-side clock source in the transmit direction of the LQG board is configured incorrectly and thus four channels of services are faulty.
As shown in the preceding figure, 1#LQG and 2#LQG are interconnected through their WDM sides and the WDM-side clock sources in the transmit directions of the two boards are configured as the line clock. In this manner, the WDM-side transmitter on 1#LQG traces the clock from 2#LQG and the WDM-side transmitter on 2#LQG traces the clock from 1#LQG. The WDM-side transmitters on the two LQG boards trace each other's clock and thus the clock signals deteriorate continuously. Consequently, exceptions occur on the WDM sides of the two boards and the services on the boards are affected. Generally, a transient CLIENT_SF, CLIENT_SD, ALM_ETH_PORT_TLOS, or ALM_ETH_PORT_RLOS alarm is reported on the client side of a board when an R_LOC or a B1_EXC alarm is generated on the WDM side of the board.
