Daily Archives: April 12, 2016

How The SSE3LWF Board Reports the OTU_LOF Alarm When Interworking with the SSE1TMR

The SSE3LWF board reports the OTU_LOF alarm when interworking with the SSE1TMR.


OptiX BWS 1600G

Fault Type

Equipment Interconnection

Optical Transponder Unit



The SSE1TMR board at station B is forced to emit light during the commissioning. Then, the

SSE3LWF board at station C reports the OTU_LOF alarm. Perform an inloop on the WDM side

of the SSE3LWF at station C. The services are normal. The adjacent channels are also normal.

In addition, it is ensured that the alarm is not caused by dispersion problem. The OTU_LOF

alarm persists.

Cause Analysis

The SSE1TMR supports AFEC and FEC encoding/decoding modes and the FEC auto-adaptation

function. The board selects the FEC encoding/decoding mode automatically according to the FEC

mode of the input signals. No manual setting is required.

When the SSE1TMR reports R_LOS and is forced to emit light, note that the FEC mode when the

board inserts ODU_AIS is the FEC mode that the board tries to perform adaptation at the last time.

If the FEC mode of the TMR is not the same as the FEC mode of the downstream LWF, the LWF

reports the OTU_LOF alarm. If the FEC mode of the TMR is the same as the FEC mode of the

downstream LWF, the downstream LWF reports the ODU_AIS alarm.


Enable the WDM-side laser of the SSE3LWF at station A and make sure that the input optical power

of the SSE1TMR is normal. The SSE1TMR automatically selects the proper FEC mode. Then, the

OTU_LOF on the downstream board is cleared.

Reference Information