A trail is A site (NE11-6-NS2 + 3-TOM)-B site -C site (NE112-13-NS2 + 2-TOM) and the wavelength is the 70th channel, 192.60, 1556.55.
At sink end ( C site ), TOM board report ODU1_PM_SSF alarm, and the connected NS2 board report OTU2_SSF and ODU2_PM_SSF alarms. The service 1xSTM-4 of TOM from A site to B site breaks down.
ODU1_PM_SSF, OTU2_SSF, ODU2_PM_SSF
Firstly, we confirmed that the trail of interrupted service is A site (NE11-6-NS2 + 3-TOM)-B site (WSD9-RMU9)- C site (NE112-13-NS2 + 2-TOM) and the interrupted wavelength is the 70th channel, 192.60, 1556.55.
Secondly, we try to disable the laser of NE11-6-NS2, but we found that the optical power of NE112-13-NS2 is normal. So the conflict of wavelength 192.60 can be at the 2 upstream sites. By the MCA board of B site, we can't find that the upstream signal from A site
have the wavelength 192.60.
Thirdly, all wavelengths of B site are analyzed. We got NE18-115-NS2 board is using the same wavelength and is connected to RMU9 board.
Finally, when the fiber connection at NE18-115-NS2 board is disconnected, the service of STM-4 at sink end is restored immediately.
By the spectrum scanning of MCA board of middle site, the 70th wavelength in the main optical line for the two directions are OK. The laser of OTU board at the
source end is disabled, the optical power of OTU board at the sink end is normal. Because the optical and electrical cross-connection configuration have never changed, the wavelength confilict is in doubt.
Frequency planning is very important for the complicated WDM network. When many frequency are used in the existing network, the newly inserted OTU board need
to be confirmed carefully that the wavelength is not used by the previous boards.