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Moving ONS shelfs to another location



I am moving a M6 shelf to another location this weekend. I am asked to check if the attenuation is still correct. I know that we can get the span values from maintenance > dwdm > retrieve spannloss. So far so good. What happends if the attenuation is to low or to high? Do I then reset the min and max values? Any help would be appreciated.


9 Replies 9


If its only a few 100 mtrs away it should be OK but if the new location is a few kilometers away then you may need to do a bit more work, you can change the Span Loss Figures in  Maint>DWDM>WDM Span Check if you get an out of span alarm after the move.

How far are you moving the shelf metres or kilometres?  Will the new location increase or decrease the fibre span losses to the adjacent nodes.

Hi and thanks so much for your reply.

The move will entail several kilometers less for one box and an unknown distance for another box.

That box will move inhouse but go over a dark fiber to wich we do not know the distance.-

The fiber spann loss will decrease for the first I reckon.

Do I need dwdm attenuators to compensate for the spannloss?

Or do I need to get rid of some

And to what do I change the vallues to?

You won't need attenuators, they will add more to the span loss, typically each additional kilometre will add another 0.25dB to the overall span loss so severn km will add approx 1.75dB which you may be OK with.

Its not just a case of the span loss there are also the channel power levels to take into consideration as well and ideally the change in design should be validated with CTP (Cisco Transport Planner) which I'm guessing you don't have access to.

If you can work out what the additional span losses are to each of the adjacent nodes you could add attenuators with the same value while the shelf is in its current location, you may get an out of span alarm but adjusting the Min and Max Expected Span Loss would clear that then you would be able to confirm that it will work in the new location before commiting yourself.

The APC (Automatic Power Control) function should be able to adjust the power levels for the individual channels over  a period of time.

I am going to try to vallidate this trough the CTP.

Thanks again for your help.

I'm not sure how big your network is but if its only 3 or 4 nodes then I would create new NeUpdate files to set the nodes up properly, in the Fibres Dialogue screen of CTP I would set the EOL Ageing Loss for 3dB that with the EOL Ageing Factor set at 1dB will give you a Min and Max Expected Span loss window of 4dB, you can open the NeUpdate file in Windows Edit to see all the various settings that will be applied when ANS is run.

Good Luck.

Hi Chris,

We did not have any issues last Sunday besides some fiber cleaning.We did have one issue that I think is a bug. If I go to maintnance, DWDM, WDM spann check and then click retrieve spann loss vallues this option is greyed out eventough I am a super user. Do you know what this could be?

Thanks in advance.

Hi, sorry I can't help with that, not seen that problem before although I have had some problems trying to change the Min and Max values in the past.  Did you use ANS to set the node up again or just relocate with the old config?

Maybe someone else has seen this problem before?

Hi Chris,

Relocated with old config. Will do a recalibration with CTP and load the new NE files to the devices. Gonna open a TAC case for the greyed out button. Thanks Chris and have a good one.

Maybe its something to do with APC and its greyed out until APC has finished sorting itself out, just a guess.

Has APC disabled itself, perhaps try starting it again on all nodes

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