When the N2SLQ16 board on an OptiX OSN 7500 NE is interconnected with the TQS board on an OptiX OSN 6800 NE, the N2SLQ16 board reports an R_LOS alarm because the TQS board emits white lights when the input optical power is normal.
Symptom
When the N2SLQ16 board on an OptiX OSN 7500 NE is interconnected with the TQS board on an OptiX OSN 6800 NE at an office and no service is deployed on the TQS board, the N2SLQ16 board reports an R_LOS alarm when the optical power is normal. After a software outloop is performed on the TQS board, the alarm reported on the N2SLQ16 board is changed to R_LOF.
Cause Analysis
No service is deployed on the TQS board. Therefore, an R_LOF not an R_LOS alarm should be reported when the TQS board is interconnected with the N2SLQ16 board and when the optical power is normal. Since the N2SLQ16 is not faulty, the possible cause of the R_LOS alarm is that signals are lost rather than that the optical power is abnormal. That is, the N2SLQ16 board may receive white lights.
Under the condition that signals are scrambled but not framed on the TQS board, the initial values of the output signals on the WDM side of the TQS board are all zero. At this time, the optical module on the TQS board outputs white lights. When a loopback is performed on the TQS board, that is, signals on the optical module are framed and scrambled for initialization, the TQS no longer outputs white lights but random signal lights. As a result, the downstream N2SLQ16 board does not report the R_LOS alarm.
Procedure
- Query the alarm mode of the OptiX OSN 6800 NE on the T2000. The result shows that the alarm mode is set to automatic reversion for the NE but the automatic reversion function is not enabled at the optical interface.
- Replace the N2SLQ16 board or the optical module on the board but the problem persists. Perform a hardware loopback at the optical interfaces on the N2SLQ16 board by using an optical fiber. The R_LOS alarm disappears. The possibility that the N2SLQ16 board or the optical module on the board is faulty is excluded.
- Analyze that the TQS board interconnected with the N2SLQ16 board may be faulty. That is, the lights transmitted by the TQS board may be white, and therefore signals on the N2SLQ16 board are lost. On the T2000, set the client-side optical interfaces on the TQS board to Outloop. At this time, the alarm on the N2SLQ16 board is changed from R_LOS to R_LOF. The fault is rectified.
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