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Pass Through OCh Creation Failure Due to Conflicting Lambda at MR8V

Publication Date:  2012-07-25 Views:  110 Downloads:  0
Issue Description
In S country, J customer DWDM testing lab.  The OCh creation is fail and denied by U2000.  This OCh is passed through FOADM station via MR8V, please refer to attached “OCh creation failure topology”.   

The version information for the system is below:

TN52 ND2T01 (3.33)
TN11 MR8V05 (1.11)
TN52 SCC01 ( V1R6C01SPC200)
U2000 V1R5C00SPC200.

Alarm Information
NO alarm information.  But Error message from U2000.  Please kindly refer attached “OCh creation failure erroe message”

Handling Process
Then, the engineer has to double check the logical fiber connection and tried.  However after a few attempts, the same problem and error message occur.  Thinking that it might be FOADM side design problem, the engineer has to logically pass through the ITL at both directions.  But, the same problem exists.  And then, the engineer revises the solution by changing the MO to IN and OUT to MI of the MR8V.  Unfortunately, the problem is still unsolved.  Lastly, the engineer has to collect all of the script file (Network Wide Configuration) and U2000 log (nemgr_OTN_XXX  & Nml_otn_XXX ) and escalate it to R & D for analysis.  After checking, R & D claim that the FOADM local add/drop lambda at A7/D7 has conflict with the pass through lambda.  R & D has suggested below solution:
  1. To modify the MR8V add/drop lambda to other lambda that is not same with the pass through lambda.
  2. To modify the pass through lambda.
  3. Pass through the conflict port (in this case A7/D7) with physical fiber and create logically at U2000.

Root Cause
From above U2000 error message displayed,   it seems that there might be absent of logical fiber connection or wrong logical fiber connection that cause the U2000 fail to recognize the proper route.  It is because the error code 1090601394 shown that it is NMS level error.

The engineer has chosen the 1st option, b y modifying the A7/D7 from lamnda 4 to lambda 20.  Then, the OCh can be created successfully.  Please kindly refer to attached video recording for the whole process.

Above incident happen due to the U2000 can detect/recognize there is lambda conflict at MR8V with the pass through lambda and it will ‘filter out’ any lambda that is similar with the local configured lambda (not necessary actual wavelength which is matched with the physical port), even though it is created logically (no real fiber connection).  In fact, it is tested that the actual wavelength remains unchanged.  It is because the changed wavelength is NOT executed to the NE level. Therefore, we can conclude that this is actually the U2000 issue.

In order to avoid this problem happen in customer actual network in the future, it is recommended that:

1. Engineer and customer shall take note on the existing MR8V wavelength information.\

2. Perform the solution mentioned at Handling Analysis.

3. U2000 shall CLEARLY displayed there is detected conflicting lambda at MR8V with the pass through lambda.  This can save a lot of time and energy to look into the root problem.