The alarm of _R_LOF_ in OSN3500 happen incorrectly when the fiber is recovered



【Problem Summary】Pakistan CMPAK--"Pakistan CMPAK "3001Sha-3013.There are some Huawei MSTP equipments issues."" 【Problem Details】The service cannot be revered automatically when the customer fixed the fibers that had been broken. SL64 board of 7500 equipment on Site A report alarm of R_LOF unconventionally, and there were no alarm of 13LSX of 6800 equipment. The service could be recovered when we take the FEC mode of 13LSX to change from AFEC to FEC on site A ,then back to AFEC.The figure below shows the affected line on the network, SL64 board reported “R_LOF”alarm on site SHA:

The status is normal when the fiber is broken.

The status is abnormal when the fiber is fixed.
The reason of the “R_LOF” in N4SL64 board reported as below:
² Reason 1：A pair of board has difficult rate of the service------cleared: the 13LSX and N4SL64 board have same service’s rate and the service configuration is STM-64(set in 13LSX board) and the remote site was not changed.
² Reason 2：The problem of fiber line------cleared: the problem is not caused by WDM fiber broken but the recovery of WDM fiber, the 13LSX board is OK (no alarms) when the fiber was recovered. The connection between 13LSX and SL64 is not changed.
² Reason 3：The receiving end on the board has some problem in SL64 board, cause the frame of signals lost ------waiting be checked, we should check the N4SL64 board.
² Reason 4：The transmission end on remote board has some problem, cause the frame of signals lost------waiting be checked, we should check the clock and the frame signals of 13LSX board.

We replaced both 13LSX board and SSN4SL64 board at site A in current network. After this step, problem didn’t reoccur upon testing, moreover, the link is working normally up till now. According to the problem analysis and steps performed during problem troubleshooting, hardware problem is suspected in either LSX or Huawei N4SL64 boards in the equipments. We found the XFP module in SL64 board has a problem after R&D analyze the 13LSX and N4SL64 board in lab. the XFP module don't deal with the signals correctly with low probability and caused the alarm of "R_LOF" reported in N4SL64 board when the fiber is recovering instantaneously. The problem was recurred in R&D's lab.the problem is reported with low probability as below: 1. the fiber from "broken" to "normal" 2. The input of optical power is about -8~-11 dBm; 3. The type of XFPis HXFP8441(03030JCB) or HXFP8240(34060322) 4. The bug in XFP module is caused by the quality of signals, which can be fixed by software upgrade.
【Resolution Summary】the XFP module in SL64 board is a problem and can be fixed by software upgrade 【Resolution Details】The new XFP will be been fixed in Q1,2014, we can replace the problem XFP with new one. And we also upgrade the version of OSN equipment to V2R12C01spc103 or R10c03 newest version(Both versions will be released on Oct, 2014) in the future.