Symptom
The SLQ4 board in the client equipment OptiX OSN 3500 interconnected with the TOM board in the OptiX OSN 6800 reports the R_LOS alarm. If you add an optical attenuator to the SLQ4 board, the alarm is cleared. In this case, the R_LOS alarm is reported again if you self-loop a client-side optical interface on the TOM board.
Cause analysis
There is a problem with the client-side optical module on the TOM board.
Procedure
1. Replace the client-side optical module on the TOM board to check whether the module is faulty. The R_LOS alarm, however, persists after the module is replaced. This indicates that the module is normal.
2. Configure the bidirectional services between a client-side optical interface on the TOM board and the client equipment. In this case, the R_LOS alarm is cleared.
3. Consult the R&D engineers. They explain that the client-side optical module on the TOM board reports the R_LOS alarm instead of the R_LOF alarm upon receipt of all "0"s or all "1"s signals if no service is configured for the module.
Result
To solve the problem, configure services for the client-side optical module on the TOM board.
