A 10G link between board A at location A) and board B (location B) is not working.
The LSX cards at both ends report OTU2_SSF and ODU2_PM_SSF.
Checked from U2000, the received and transmitted optical power is OK both ends.
The path between the boards is clear, easy to trace by trail manager.
The OTU parameters (mapping mode, frequency, FEC, etc.) set to the same on board A and board B.
Our staff has visited location B. He applied loopback on board B. The loop was successful, the OTU2 and ODU2 alarms disappeared on board B during the loop.
Meantime the other side reported R_LOS and OCH_LOS_P along with the OTU2_SSF and ODU2_PM_SSF as expected, the received power dropped under -60 dBm.
Removing the loop and restoring the original fiber layout, the former power level returned on board A.
(The R_LOS and the OCH_SSF_P have gone on board A. The OTU2_SSF and ODU2_PM_SSF remained at both ends.)
This way the improper connection of fibers � especially between multiplexer/demultiplexer and transponder � could be excluded.
The next available time, our staff has visited location A. First he applied a board self-loop at WDM side on board A.
The OTU2_SSF and ODU2_PM_SSF did not disappear.
He modified the client mapping mode on the faulty LSX (still in self-loop state). When setting FEC instead of AFEC, the ODU2_PM_SSF disappeared (mistakenly…).
The OTU2_SSF remained.
Then he gave a loop at the WDM side towards the other card, board B.
The opposite card reported an IN_PWR_LOW only, the link stood up properly.
We could state that board B and the whole transmission path, including all intermediate boards and the fiber layout was OK.
Then he restored the original fiber connections, the OTU2_SSF and the ODU2_PM_SSF returned at both ends.
OTU2_SSF and ODU2_PM_SSF on the LSX cards at both ends
Board replacement at location A.
Board A was broken, both transmit and receive directions.
This could result, when interconnected with any opposite LSX, both ends reported the referred alarms.
It has very low probability such case to occur.