Fibre cores...
 

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?

Re: Fibre cores...
 

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

Re: Fibre cores...
 

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.

Re: Fibre cores...
 

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

Re: Fibre cores...
 

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 :)

Re: Fibre cores...
 

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!

Re: Fibre cores...
 

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 :)

Re: Fibre cores...
 

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

Re: Fibre cores...
 

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.

Re: Fibre cores...
 

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! :p:

Re: Fibre cores...
 

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.

Re: Fibre cores...
 

See this ...
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.

Re: Fibre cores...
 

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

Re: Fibre cores...
 

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 :)

Re: Fibre cores...
 

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

Re: Fibre cores...
 

And now i need a source for Fibre routers, if they even exist...

Nothing seems to be showing up on a quick half hour google that's suitable :(

---------- Post added at 13:52 ---------- Previous post was at 13:39 ----------

Forget Fibre routers... Duh, i meant switches, got 2 of them, now scouting for prices of the TC3300. Then these will be wired to Gigabit routers, and so on...

Next up, get the network subnetted correctly...

Re: Fibre cores...
 

Are you sure you mean a router? - Ah, you don't mean a router!

Summat like this SmartSwitch from Netgear will connect each end of the fibre to up to 24 x 10/100 Mbps Ethernet devices - PoE too!

http://www.netgear.com/Products/Swit...s/FS728TP.aspx

You'll just need a couple of SFP GBICs to connect to the fibre. Don't buy new though as loads turn up for pence on ebay.

http://cgi.ebay.co.uk/ws/eBayISAPI.d...m=290113791640

Re: Fibre cores...
 

Interesting

Dru where are you doing this ? Home or in the office ?

Re: Fibre cores...
 

At college, like i said, it's a scenario, i'm in wayt over my head on it. Sadly.

We're not actually doing it, we just have to make sure it would work in theory.
Which reminds me... I have to find a way to connect the two buildings router to router (after the switches to change from Fibre to Ethernet) And then subnet each room whilst still allowing them to access the main internet connection (connected to one of the main routers)

Yep, my scenario is both confusing and a mess :(

Re: Fibre cores...
 

Why do you need to subnet each room ? :confused:

Do you envisage seeing a lot of hdcp / arp traffic ? How many computers should this network be capable of ?

Re: Fibre cores...
 

It was an idea, i don't know if it's right or not. Either way i think my network set up is completely wrong, i just seem to get confused by it all.

I get really confused when deciding what could do what and how :(

EDIT:
It's one Switch per room, and one side has about 6 rooms, whereas the other has 2.
One room has a wireless access point....
I'm really usnure as to how to go about this. Oh, and the routers are One each for each building.

Re: Fibre cores...
 

What do you think is wrong with it ? ;)

Re: Fibre cores...
 

Ah, i think it's wrong because if i subnet it, the routers wouldn't know how to differentiate between each PC in each room from the switch.

I avoided using routers all out because they're a pain, in other words, my understanding of how to put together a more segmented network is very limited.

Thing is, i could let the routers dish out DHCP addresses that have half a pool for one part of the building and the other half for the other half of the building, then tell Router2 to route through router1 for the internet and the other bit of network access.
Just, how would i go about this? OR am i even on the right track?

I've missed about 6 network lessons this year, and we've not had a tutor for the half i have attended :S (My stomach is fantastically weak :()

Re: Fibre cores...
 

Hmmmmm no.

I won't give u an answer either but maybe guide u to this :

This is a very simple solution but from here you should try to identify bottlenecks and dependencies.

Solve this : Then move on to VLANs if you have time.

Think 1 big subnet 10.0.0.0/255.255.0.0

Think of network services being issued by machines not routers.

Think of being able to move file/network servers from one building to another without disruption.

Think of switchable ports on the switches connecting the PCs ie student on 10mbs and network servers on 1gbps ports.

Think peak network traffic and how to scale : 1000pcs x 10mbps = Hmmmmmmmm wrong
More like switch bandwidth divided by no of pcs per switch

---------- Post added at 14:02 ---------- Previous post was at 13:51 ----------

hint :

The bandwidth from switch 1 to router 1 is 1gpbs
The bandwidth from switch 2 to router 1 is 1gpbs
etc etc etc etc

So is there only a peak of 6gbps flowing through the fibre ?

---------- Post added at 14:05 ---------- Previous post was at 14:02 ----------

DOH :doh: Does your project require the network to be segmented ?

Re: Fibre cores...
 

So how in my current setup could i get both routers to assign different addresses in the same Class B subnet? Wouldn't they assign the same addresses by accident?

Also, the largest room has about 10 PC's in it, each using 10/100 cards. Not gigabit. Everything from the switches onwards however is gigabit.
This would mean at any one time a room can only pull 100Mbit. (And i doubt switches are that efficient somehow :p:) and there are about 7 (maybe 8) rooms in the first building. So, this is, at peak load, at the highest amount of pc's, about 100mbit x7 (or 8) = 700Mbit/800Mbit, out of 1000Mbit available (at optimum rates etc...)

Is that viable? Or should i say, do you think i've planned the bandwidth correctly?

EDIT: The Fibre is only carrying 1Gbps, it's only Fibre because i can't think of any other solution to carry 1Gbps over 400m. Apparantly the tutor thinks it's probably the best possible way of doing it (The Fibre connection that is)

EDIT2: My solution does not require the network to be segmented, i just assumed it would be easiest. Looking at it, it's not :p:

Re: Fibre cores...
 

Ask yourself why you want to be doing that when 1 router can happily do that for everyone. Think of router 2 now being simply one large switch.

ps your bandwidth is fine then :) Probably will still have to restrict student traffic though : you know what they are like ;)

Well theoretically segmentation is the way to go but what I'm trying to highlight is that even with segmentation you don't need both those routers dishing out DHCP as a DHCP request can be fullfilled right across the network.

ie PC1 on switch 1 could get an IP address from router 2 it is possible :)

Re: Fibre cores...
 

I didn't know that could be done, and as for the router acting as a huge switch, would i still be able to assign static IP's through it, should i want to?


And my last question i can think of right now, is there a specific name for the routing mode i'd need on the second router? Gateway or bridge or something... I think i need to look into all this again, i just seem to be more confused.

Re: Fibre cores...
 

I'm trying to get what level your course wants :erm:

GO TO LECTURES KID don't end up like me. :tu:

Typically I would not have router 2 but have a managed switch there which I can configure VLANs if needs be.

Read about managed switches and VLANs dude.

http://en.wikipedia.org/wiki/Network_switch

Re: Fibre cores...
 

I'll concur with CRC. It sounds like you're making it much more complicated than it needs to be. I'd just daisy-chain the gigabit ports of all the switches (using fibre wherever sensible) and hang the one router from one of the 10/100 ports of one of them.

If that doesn't give you enough bandwidth then I'd modify that slightly to have a star arangement with one, expensive, gigabit switch in the middle. This is also a bit more fault tolerant so that, if one of the gigabit links fails, you'll only lose the PCs connected to the one switch instead of splitting your whole network in two.

Bit of an overstatement but - switches are fast and routers are slow.