Symptom
At the ROADM station consisting of the OptiX OSN 6800 V1R2, the signal flow in the wavelength add direction is as follows: L4G->M40V->WSM9->OAU->FIU. After the internal logical fiber connections are complete at the NE, create the single-station optical cross-connections and select the automatic optical power adjustment function. Then, the T2000 prompts that the creation is successful. The OAU board, however, reports the MUT_LOS alarm. No alarm is generated on other boards.
Cause analysis
The OPA supports only the WSD9, WSM9, RMU9, and ROAM boards. In the case of other boards supporting the setting of attenuation (VA1/M40V/D40V), the OPA does not set the attenuation. Thus, you need to set the attenuation. During the calculation, OPA regards the attenuation as zero (0) and the changes in the attenuation of the boards does not trigger the re-adjustment by the OPA.
By default, the VA1, M40V, and D40V take the maximum attenuation for each channel. Hence, when the OPA function is started, the light from the L4G does not enter the OAU after passing the M40V because the attenuator of the M40V is not adjusted.
Procedure
Adjust the M40V on the T2000 and set the attenuation value of the corresponding channel to 0 dB. Then, the MUT_LOS alarm is cleared.
Reference Information
In certain scenarios, the attenuation of certain channels of the M40V, D40V, VA1, and VA4 boards needs to be set manually. At the station that is configured with the M40V, D40V, VA1, or VA4, set the attenuation value of the optical channel of the board manually to ensure the availability of the optical channel. This is very important for the ASON feature to trigger rerouting in the WDM network.
