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The N2SLQ16 Connected to the TQS on the NGWDM Reports an R_LOS Alarm Due to White Light Transmitted by the TQS in the Case of Normal Optical Power Input

Publication Date:  2012-07-25 Views:  46 Downloads:  0
Issue Description
In an office, the N2SLQ16 board on the OptiX OSN 7500 is connected to the TQS board on the NGWDM. The N2SLQ16 reports an R_LOS alarm when the optical power input is normal. The N2SLQ16 board reports an R_LOF alarm when outloop of the TQS is created through software settings. No service is configured on the TQS
Alarm Information
R_LOS
Handling Process

1.         Check the alarm inversion menu on the iManager T2000 to query whether manual alarm inversion is enabled on the port.

2.         The NE is configured with automatic alarm inversion and the alarm inversion function is disabled on the port. The problem is not caused by the alarm inversion settings.

To check whether the N2SLQ16 or the optical module is faulty, replace the optical module or the N2SLQ16.

The problem persists.

Create a physical loopback of the port of the N2SLQ16.

The R_LOS alarm is cleared. This means that both the N2SLQ16 and the optical module are normal.

3.         Analyze the problem again.

The problem might be caused by the TQS connected to the N2SLQ16. The R_LOS alarm reported by the N2SLQ16 might be generated due to white light transmitted by the TQS.

Create a logical outloop of the TQS. 

The alarm reported by the N2SLQ16 is cleared. After loopback, the N2SLQ16 reports an R_LOF alarm instead of the R_LOS alarm. The problem is solved.
Root Cause

The N2SLQ16 connected to the TQS that is not configured with services is expected to report the R_LOF alarm instead of the R_LOS alarm in the case of normal optical power input. The N2SLQ16 reports the R_LOS alarm probably because it receives white light.

The initialized value of the logical chip is all zeros when the logic of the TQS does not perform framing of signal scrambling. In this case, the TQS optical module transmits white light. Loopback of the TQS means framing and scrambling initialization of the optical module. In this case, the TQS transmits random signal light instead of white light. Therefore, the downstream N2SLQ16 stops reporting the R_LOS alarm.
Suggestions
If the TQS is not configured with services, the optical module that is not initialized might transmit white light (that is, all 1s). In this case, the downstream port might report an R_LOS alarm even though the optical power is normal. To initialize the optical module of the TQS, loop back the TQS or configure the TQS with services.

END