Daisy chaining fibre cable

[gh5000]

Hi all,

 

Currently the school has their servers in location A. In there, there is also our ISP connection and a few links to some of our edge switches.

 

There is also a link to location B (only 8 cores) where the servers used to reside. In location B there are fibre links to around 16 cabinets.

 

There is a mix of fibre grades, at least one OM1, some OM2 & some OM3 from location B to the edge.

 

What I would like to do is put in a bigger fibre from A to B and patch all the edge switches currently going to location B back to location A so I would be operating more of a star network.

 

If I put in an OM4 48 core link from A to B, would it be backwards compatible with the OM1, 2 & 3 links or would I have to match each of the grades currently coming into the cabinet?

 

Thanks

[3s-gtech]

No, it won't be backwards compatible for direct joining - you'd be mixing 50/125ɥm with 62.5/125ɥm. We have some areas where we've needed to do similar (source link is OM4, continuing on to an old OM1 fibre) so we just use a sparsely populated switch as a media converter (the join as at a cabinet anyway).

[gh5000]

@3s-gtech - in my case would that only be for the single OM1 cable join. Any OM2/OM3/OM4 direct joins would be 50/125ɥm and therefore ok?

[3s-gtech]

No, OM2 is the same as OM1 (62.5/125ɥm). OM3 and OM4 should join okay as they're compatible.

[Achandler]

The issue you have, is putting in fibre capable of 1GB and not 10GB seems pointless but you are stuck with options at the moment because of the 2nd legs of the runs.

 

I assume its not possible (due to cost) to replace all the OM1/ OM2 linsk at once?

[PotNoodleTech]

You can actually mix 62.5 and 50 fibre cable if you absoloutly have to, it isn't recommended as you can get a up to a 5db signal loss. Now whether that signal loss actually gives you any issues whilst running with high quality media convertors over short distances at 1Gb/s is a whole 'nother ball game. It hasn't for me. Clearly it wouldn't work at 10Gb/s.

 

I've mixed here in certain areas, only because the resulting cost of not mixing and having to have new fibre run across the site was so excessive as to be completely unfeasible.

 

I'd rather have mixed fibre links all going nicely back to the core switch, than never-ending daisy chains cab onto cab, switch after switch.

 

If you can avoid mixing then do it!

[Michael]

I agree, direct joining isn't a good idea due to the different types of fibre in use. Of course one possibility is a fibre switch, fed by a 10Gb link from A to B, then from B to end points.

 

In this scenario all of the mixed types should work without issue.