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PA problem lead to OTU3_LOF alarm of TN54NS3

Publication Date:  2012-07-25 Views:  140 Downloads:  0

Issue Description

Relative version: V1R6C00SPC300
Relative equipment: OSN8800
One 40G link of a new 40G project , there just have one 40G lambda from site A to site B.  The 40G board is TN54NS3.  At site B had OTU3_LOF alarm. and the opposite is normal.

Alarm Information


Handling Process

Replace theTN54NS3 board . 

Root Cause

OTU3_LOF is an alarm indicating that the frame alignment signal (FAS) is abnormal. This alarm occurs when the frame alignment processing is out of frame (OOF) in three consecutive milliseconds.

Possible Causes
Cause 1: The settings of the service type or FEC type are incorrect.
Cause 2: The board that reports the alarm is faulty.
Cause 3: The receive optical power or the OSNR of the local board is abnormal.
Cause 4: The signals transmitted by the corresponding board at the opposite end do not have a frame structure.
Cause 5: The fiber of the transmission line is abnormal.
Cause 6: The dispersion compensation value is excessively great or small.
Checking the causes one by one:
For the TN54NS3 board, the main causes of this alarm are the receive power , OSNR and the dispersion compensation  abnormal. But by checking the receive power(-5.7dBm) ,OSNR(the same link ,A site is normal)and the DC(by checking the DCM configuration) are normal.
So, the TN54NS3 board maybe have problem.

The 40G transponder frame as below:
1.checking A point's power(IN power) by navigator script:per-get-curdata-new:lsiopcur,15m,0xff,LASER_GROUP,34,"board=soltID,subcard=255,port=1,group=1"
2.checking B point's power(PA out power) by navigator script:woptp:slotID,1,83,1,f1,03,00,0b
Result:abnormal "PA OutPower = [-287]"
3.checking C point's power(TDC out power) by navigator script::woptp:slotID,1,83,1,f1,03,00,0c
Result:abnormal "LINE InPower = [-600]"

So , the result is that :the PA is bad of this NS3 board.


By this case, the PA issue also cause the OTU3_LOF alarm. 
So when doing the commissioning, should care about the receive power of the 40G board.  The PA module will be destroyed if there is high power in.