Building to Building Link

[beany1]

Hi all,

 

Onsite we have a small building that is currently linked to the main building using an old 100mb fiber link, cabinet to cabinet is less that 50 meters and there is already a sunken PVC channel. It has been in for years, been moved around, damaged and it's extremely slow even for 100mb. After September the number of users in there will increase to around 15 concurrent, so I want to replace the link.

 

Question is, for cost and current setup we could only replace it with 1gb fiber. So I was wondering if I was to use Cat5e External Grade LDPE UTP instead on 1gb ports, would I effectively get the same result? From my understanding, fiber would just allow me to go further distances? - Which I don't need. With CAT5 we could then run multiple cables and use port trunking which would allow 2gb.

 

Any thoughts?

[Achandler]

Put high end fibre in,and then 8 cables. You could then trunk the ports (same as cat5) but if you put fibre capable of 10Gb in the future then you are future proofing as well.

[beany1]

hmm, sounds lovely however budget won't allow.

Literally choice is 1GB fibre or a couple of CAT5e cables at 1GB. Need to replace both switches and the link cabling so if it was fiber I'd have to get a company in...assuming this would cost lots or CAT5 which I could do. So in this situation would 1GB fiber be the same as 1GB CAT5?

[Achandler]

If the run is as easy as you say then you can order pre-terminated fibre cables of a predefined length, which wouldn't cost as much. You can buy it at about 90p a metre (8 core OM3).

 

You then need two fibre patch bays (about £30) each.

 

Otherwise yes for that run you could use CAT5 cable and you should get a similar result, personally I would consider fibre though if the run is straight and easy, with not harsh corners.

[andyrite]

Fibre or Cat5e will give you the same speed. Fibre will just cost a lot more.

[beany1]

Yeah I looked at comms express previously, the cable and patch panel ain't too expensive, its the switch to go with it. Cheapest HP switch with 10GBe is the 2910al-24G (I believe??) costs over £1000 which doesn't include the cost of the SFP modules (could be wrong I just used the HP Switch chooser)? We are only a primary and as the building the link goes to is only small, I can't imagine ever having more that 20 people down there.

[hallb15]

What condition is the sunken PVC channel in? If its old and been moved around a lot as you mention, it may be tricky getting copper or fiber through it.

Have you considered a wireless link?

[Michael]

Being only 50m you'll notice no difference between CAT5 and fibre, however fibre has no electromagnetic properties so it won't attract lightening strikes, whereas copper can. I'd install either OM2 or OM3 which should be capable of 10Gbps for 50m no problem.

 

Of course if this did happen in a worse case scenario, it would kill or damage your switches at both ends, so please bear this in mind

[beany1]

@hallb15 sorry, I was referring to the fiber within the two buildings, both have been moved a lot, and had new cabinets put it - I was informed when I started that a couple of the plugs were ripped off during moving! AFAIK the channel is OK.

@Michael I've heard of the lightning problem, I was under the impression if you used outdoor CAT5 inside a channel buried in the ground that it wouldn't be affected is this wrong? Is there a solution to this? Or is it literally a case of this is why fiber is used?

 

So if i'm understanding correctly I probably be using OM3 but with a 1GB fiber SFP module as that's all we can afford?

[Michael]

Under the ground 'should' be OK, but when it's in the air definitely use fibre. I'd highly recommend OM3 with 1Gbps SFPs definitely, then upgrade to 10Gbps when required. It's easy then

[beany1]

So next question, if I buy the length of preterminated cable - does that mean it has plugs on either end which connect directly to the patch panel? no special tools required?

Then cores - if I was to buy 8 core as previously suggested does that mean its one cable with 8 connections so in theory I could connect 8 separate fiber modules?

[Michael]

If you buy a length ready made, it should have LC to LC 50/125μm connections which would bypass the patch panel and plug directly into an SFP, which then plugs into the switch. Generally this is sufficient as it won't be moved or changed for most probably years.

 

Alternatively ST to ST 50/125μm, then from the patch panel ST to LC.

[Michael]

There's no real advantage to buying multiple cores as OM3 will run 1Gbps or 10Gbps. With it being a short run you shouldn't have any problems, unless you think you need additional capacity? More cores = more money.

[Chris_]

Can you get 1 pair fibre? If you got 4 or 8 core fibre you could use two pairs to have 2x 1GB links if you need the extra bandwidth and would allow for a pair failing.

[Achandler]

We always use to run at least double what we needed, because the extra cost versus time made no sense not to but then we are a secondary school. If we needed 4 we would run 8 and it has proved a good idea to because the amount of times I have used the extras has been countless.

[beany1]

Cheers everyone,

 

So the following bits i'm considering:

2 * HP 1910-24G (1 for main building, 1 for the small building)

2* HP X120 1G SFP LC SX Transceiver (JD118B) (One for each switch - is that correct?)

1 * 50 metre LC to LC Multimode Preterminated Fibre Cable 50/125 OM3 4 Core

 

Is that's all thats required?

Edited June 21, 2013 by beany1
wrong SFP

[Achandler]

Yep, that should be all.

[Michael]

That'll all work fine, but it doesn't have 10Gbps fibre options (just so you know).

[john]

For 15 users do you really need 10Gbe? It sounds huge. Campus links for hundreds of users yes but 15 users if they are editing and streaming HD Video solidly all day then I could see the need but if its just general use then 1 or 2Gb would be fine

[Achandler]

Personally I said spec the fibre for up to 10Gb as it will likely be used in 10-15 years, when things could have changed.

 

His current plan for running at 1Gb only is fine.

[john]

Personally I said spec the fibre for up to 10Gb as it will likely be used in 10-15 years, when things could have changed.

 

His current plan for running at 1Gb only is fine.

 

More picking up others comments about 10Gbe. I would spec OM3 fibre / single Mode if its a long long run for all jobs given it will do 10Gbe but a lot of people on here of late are running to 10Gbe and I don't think they realise just how much traffic they are doing they would be surprised.

[beany1]

I agree with 10GBe being overkill - simply couldn't afford it.

 

Am I correct in assuming though that the cable in that spec is compatible with 10GBe and that to make it 10GBe in the future I would replace the switch and SFP modules?

[john]

I agree with 10GBe being overkill - simply couldn't afford it.

 

Am I correct in assuming though that the cable in that spec is compatible with 10GBe and that to make it 10GBe in the future I would replace the switch and SFP modules?

 

Yep just change the bits required at each end so in your case with the kid you said you were looking at that would be a new switch and module

[Michael]

Yes - 10Gbps Fibre uses the same ends, but 10Gbps SFP modules are slightly fatter than 1Gbps SFP modules and are typically located on the back of the switch rather than the front.

[beany1]

Thanks everyone for all your help!

 

Fingers crossed I won't bugger it up!