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New Member

ONS 15454: 1 node got LOS alarm, the other does not?

Hello everyone,

I've got a problem with my ONS system. As you can see in the figure, the first one is CTC view of Node1 and the second one is Node2.

In LINEAR model, side B of Node1 connect to side A of Node2. But take a look at them, side B of Node1 is working normally, no alarm. But side A of node 2 is RED with Los of signal alarm.

My traffic is still working good between 2 Node. It is so strange, I have never been experienced the error like this before. Please tell me what this situation is? Thank you very much.


   Figure1 - CTC view from node1


  Figure2 - CTC view from node2

Cisco Employee

Re: ONS 15454: 1 node got LOS alarm, the other does not?


Most likely you have an asymmetrical fiber loss (verify WDM span check on both nodes) or the power failure low thresholds are tuned differently on the OSC-SCM cards.

There are no amplifiers on that link, hence, LOS is informative message indicating the threshold is exceeded, but apparently, that power level is still good enough for the muxponder to work.

Having an amplifier would bring the connection down as on LOS amplifiers are shut down due to security requirements.



New Member

Re: ONS 15454: 1 node got LOS alarm, the other does not?

Dear Alexei,

Thanks a lot for your reply. As you said, the problem is supposed to be the parameters on OSC-CSM cards are not equal. I will re-import the parameter from Metro planner into these card and check.