Fault Description:

Initially an R_LOF alarm was reported on the IN port of LWF board within STM-64 MSP ring, and then iterations are observed in R_LOF alarm, and BEFFEC warnings, thereby triggering protection alarms/APS_INDI on OSN 3500 integrated with BWS 1600G, at Site A and Site B.

Alarm Information: None.

Causes:

The probable causes are as follows:

· Optical power degradation.
· Faulty patch cords/Dirty Patch cords.
· Faulty Attenuator (s).
· Faulty LWF board.

Procedure:

1. Check whether optical power degradation is observed at OA section of the link.
2. Check whether Optical power degradation observed at Rx/IN port of the LWF board.
3. Use OSA to check whether configured wavelength is being received from the Far end.
4. Replace existing attenuators (if any), to check if they are faulty or dusty.
5. Replace patch cords connecting IN/OUT port towards Mux/Demux boards.
6. Apply self-loop to the LWF board, by connecting IN port to the Out port (adding 7db attenuator is recommended), and Rx port to the Tx port of the same board (again adding 7db attenuator is recommended), and check if the R_LOF alarm and BEFFEC warnings are cleared.
7. If alarm persists even after applying self-loop, then replace the LWF board.

Conclusion:

After executing all the troubleshooting steps, it was diagnosed, that corresponding LWF board is faulty, and was replaced to clear all the alarms, and link became normal.

Suggestions:

All necessary troubleshooting tools and spares.

Thorough technical aspects while troubleshooting R_LOF alarm, thanks for sharing. It has greatly contributed to my knowledge and experience.

seems like you have sound technical experience, precisely explained!

Thank You Razzaq and Philander, for your valuable input and appreciation.

and how about same R_LOF alarm appears on the Rx side of the LWF?

Thanks for your input, in order to respond to your question, i am considering the same scenario, with R_LOF alarm on the Rx side, and i will be responding to your question in my next thread, stay tuned!

Good question Tony, looking forward for the response from Mr. Faheem

And what causes OTU_LOF alarm?

Hi Serene.me,

I have shared a new post to answer your query, hope it helps.

check it out: http://support.huawei.com/huaweiconnect/thread-353991.html

Thanks for the prompt response.