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ITL addition failed due to lambda deviation

Publication Date:  2012-07-25 Views:  108 Downloads:  0
Issue Description
in XXXX metro wdm network, the route of 193.3 lambdas is from A site via B site to C site. the service is running normal, but after ITL addition in D site, the service is down.
Topology as below:




Alarm Information
R_LOS & OTU_LOF


Handling Process
Change the transponder board (LSX) in A site, the version and type should be same as the board in C site which frequency is also 193.3. After change the board in LVSB at the PE time, the input power and perfomance both are ok for this trail. The issue is solved.



Root Cause
The wavelength info in A site by OSA reading

From the upper table, the wavelength is 193.279 scanned by OSA, which drift about 21GHz from central frequency. but in the index for 80 lambdas system, the central frequency deviation should be less than +/- 5GHz.
 After the wavelength deviation, it will degrade the optical power and performance in receive end, create the extra system cost. After add ITL board, it will create the ITL board insertion loss cost, and also OSNR cost because of the interleaver board will filter the wavelength. All above aspect can degrade the performance of the receiver, and finally the service maybe down.







Suggestions
The frequency deviation happened in the transponder board, which lead to the performance degrade in receiver, and also the interleaver (ITL) filter the signal power because of the frequency deviation, the performance will be more lower, then the service is down.



END