Fibre cores...

[Druchii]

Ok, casn anyone give me a quick rundown on the differences between different amounts of cores in a standard armoured fibre cable? I have choices of 4 cores, 8 cores, 16 cores and 24 cores, it's spanning 400metres and will only see 5 bends max. (At a max bend of 90 degrees each)

I need help on this, i've chosen the type
50/125 OM2....

I'm in well over my head, this is for a scenario at college, and i just can't find anything to do with it, i'd aprreciate if noone said do my own work, or just google, cos i have, and now i can't find a thing :S

Help?

[Wicked_and_Crazy]

Surely the number of cores has to be driven by the bandwidth it would need to provide

[Druchii]

In which case, i'm looking for upto a gigabit of bandwidth.

Oops, i really feel thick now, i only need Single Mode as it's point to point,. not multi-mode... Which changes my cable preference.

Looking here: http://www.universal-cables.co.uk/fi...re.htm#results

With the options set to:
Single mode 9/125 OS1
Cores.... I dunno.
Steel Wire Armoured LZSH
Construction set to all.

[Wicked_and_Crazy]

You need to find out the bandwidth distance product of the fibres your looking at. As you know the bandwidth and the distance you require should be able to determine which cable is most suitable

use the analogy that electricity will flow like water

a flow in one big pipe = low pressure - or low 'resistance' in electrical terms

the same flow in multiple smaller pipes, with the same collective volume as the big one will result in a higher 'back' pressure, and speaking electrically a higher resistance ... 4 core, 8 core etc will have different values which may mean the overall power available could be a problem


then - each bend introduces a further resistance...

- will your signal get through

[Druchii]

Gah, i really don't have time to work all of this out if i'm honest >< I have about 15mins tops to spend on this one building to building link...

I chose fibre as it's 400m to cover, line of sight isn't great and speeds need to be fast

I'm thinking of going for 12 cores for a balance between speed and resistance... But i'm going to have to pull it out my @rse to be able to convince them... Oh, and 475m, which allows for all sorts, costs around £1010... Ouch!

Originally Posted by Druchii

Gah, i really don't have time to work all of this out if i'm honest >< I have about 15mins tops to spend on this one building to building link...

I chose fibre as it's 400m to cover, line of sight isn't great and speeds need to be fast

I'm thinking of going for 12 cores for a balance between speed and resistance... But i'm going to have to pull it out my @rse to be able to convince them... Oh, and 475m, which allows for all sorts, costs around £1010... Ouch!

the real world solution is still dependent on the power available, you cannot expand beyond that, reducing the cores will manage that more easily, in my opinion go for 8, but it is up to you

[Druchii]

Originally Posted by homealone

the real world solution is still dependent on the power available, you cannot expand beyond that, reducing the cores will manage that more easily, in my opinion go for 8, but it is up to you

That sounds like a good idea to me.... Thanks

[printerman]

How are they connecting at each end.? Is it directly to a cabinet? This should determine your connections required.

Whats the distance? This will determine if its OS1 or OM2 or OM3. Depending a a campu size OM3 is normal. I'd use this over OM2 as it is upgradable in the future if you need 10 gig (I think), It been a while since i dealt with fibre. Your bends should be fine, but don't go fixing them at 90 degrees. Just let your cables be tidy but sit natturally.

Whats your Insertion and RL Budget? Are the connections 2.5mm or 1.25mm ferrule connections? This will determine your connector and cabling type. Good connectors will give you low loss. bad connectors will give you high loss.

You also have to consider the polishing specification. If its OM3 you can hand polish them and they'll work. If you chose OS1 you have to buy them in 'cos they have to be machine polished. If you need very low RL then you'll havr to buy APC connectors not just PC.....there are a lot of questions you haven't answered.!!

OK looking at what you typed.

OM3 MM cable which is upgradable and cheap. You still need to know your connection quantity.but lets say you are connecting one pc to a cabinet. One connection will work. Use one connection for each pc say.

[Druchii]

It's a link from Fibre router to Fibre router, however i can't find the ones i was going to use for this task. I have it wirrten down at college, so i'll be able to find out later at some point. I'll let the cables flow as freely as possible.

Gah, so complicated!

[timwilky]

Whenever I have had fibre installed. I have only ever actually needed a pair. (Or two when we used to use fddi in the dark ages. However, I always have at least 4 times the ammount I need installed. Why.

Labour to pull it is the same irrespective of the amount of cores. That is the expensive, time consumming element and if suddenly you need to install a second pair etc you would look a proper wally.

[handyman]

See this ...

Both multi-mode and single-mode fibers are used in communications, with multi-mode fiber used mostly for short distances (up to 500 m)

Taken from the wiki on optical fibre.

It also states that single fibres can handle upto 40Gbs so probably the lowest spec multi-mode fibre will cover the job.

[Wicked_and_Crazy]

Originally Posted by Druchii

Gah, i really don't have time to work all of this out if i'm honest >< I have about 15mins tops to spend on this one building to building link...

Sounds like a wannabe consultant cant be bothered to do it themself but will ask others to do it for them

[Druchii]

Originally Posted by Wicked_and_Crazy

Sounds like a wannabe consultant cant be bothered to do it themself but will ask others to do it for them

Yep, pretty much, it's nothign like that thoguh as it's just a crap scenario, we're marked on what we can find to do the job and how we would set it up... However i have no idea when it comes to Fibre, hence asking for the help

Probably gonna go somewhere between 8 - 16 cores then

[handyman]

Originally Posted by Druchii

Yep, pretty much, it's nothign like that thoguh as it's just a crap scenario, we're marked on what we can find to do the job and how we would set it up... However i have no idea when it comes to Fibre, hence asking for the help

Probably gonna go somewhere between 8 - 16 cores then

I have a cisco book at home that has the right answer in it but I can't remember offhand.