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Wireless Networks Thread, How fast are your links to feeder cabinets? What are you using Fibre/Ethernet, both? in Technical; Hi all, I'd be really interested to know what links schools have from their main cabinet to feeder cabinets. Have ...
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    How fast are your links to feeder cabinets? What are you using Fibre/Ethernet, both?

    Hi all,

    I'd be really interested to know what links schools have from their main cabinet to feeder cabinets. Have you got 1 fibre cable to each cabinet? are you using Ethernet or both, is the fibre OM1 (1gb) or OM3 (10Gb) etc.?

    We have one main cabinet with 2 X HP 4108GL's connected together via GB stack. Our 7 feeder cabinets all have an OM1 1Gb fibre cable going to one switch in the cabinet. Some cabinets have 1 switch, some 2 and some even 3 or 4. To increase speed quickly and cheaply we have run some CAT5E to a couple of the cabinets close by which have multiple switches. The top switch is already connected via fibre then for the other 2 or 3 switches we have added a CAT5E cable which runs back to a 1GB port on the core switch. It seems to work well and you can pick up 6 or 24 port modules for the 4018GL pretty cheap.

    All our HP Procurve switches are running at 100/100 but ideally we would like to replace them for GB and look at replacing the core switch. Problem is, if the pipe back is generally just a 1Gb fibre, I really can't see there will be a gain and it seems too messy to be running the amount of Ethernet cable you would need to provide a suitable pipe -I would say you need 4GB per 48 10/100/1000 switch.

    Are schools using OM3 10Gb fibre or have you done the same as us or have people got GB switches with just one 1Gb fibre cable back to the main cabinet?

    10Gb fibre just looks too expensive to me!

    Thanks very much in advance.

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    RabbieBurns's Avatar
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    90% of our core to edge switches is 10gb fibre. Where we havent been able to stack switches, we LAG 4x1gb links between switches to increase bandwidth.

    The remaining 10% are 1gb fibre runs, but this is down to the modules at either end, so these have been budgeted for and are being replaced soon.

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    ronnoco (23rd June 2011)

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    The real question is: how much of the capacity you have installed is being used, and what are you using to monitor it?

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    ronnoco (23rd June 2011)

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    ^ Basically that, it's surprising how much a bog-standard 1GB link (or 2GB LAG) can handle for everyday usage.

    Point Cacti at your switches, monitor for a typical month and see what your network is actually doing (and what the cpu load on your switches are).

    Without a "we need to upgrade because of $foo" and here's the logs to prove it, I'd deny your request unless I personally knew your request had merit.

    ----

    We have 2GB links between cabinets currently and we're not seeing bottlenecks there.
    Last edited by pete; 23rd June 2011 at 05:03 PM.

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    We have 3 cabinets, 1 (server room) ,2 and 3. 1 and 2 are linked via fiber running at 10gig, 1 is connected to 3 via 4 cat6a cables trunked to give a 4 gig link. There is then another 4 gig trunk for redundancy running between cabs 2 and 3. All client connections are gig, and sever connections range from 1 gig to 4 gig.

    Steve

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    ronnoco (23rd June 2011)

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    IanT's Avatar
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    Each switch on the edge has 2Gig per switch

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    Marci's Avatar
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    2Gb LAG Fibre to each cabinet from the core, except for our MFL wing which has a 10Gb link.

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    localzuk's Avatar
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    Every switch in our school connects back to the core via a 1Gb fibre. So if a cabinet has 3 switches in, then that cabinet has 3Gb connectivity back to the core.

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    Quote Originally Posted by localzuk View Post
    Every switch in our school connects back to the core via a 1Gb fibre. So if a cabinet has 3 switches in, then that cabinet has 3Gb connectivity back to the core.
    I'm the same pretty much.

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    1Gb link back per switch here as well on OM2 fiber, 100Mb to the desktop.

    Most switches are 24-port, got the odd 48-port here and there but tried to avoid them if I could due to the fan noise

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    It's pretty difficult to fill a 1Gb fibre link and replacing the switches themselves can make all the difference. The switching capacity and onboard memory is very influential to the speeds you can expect.

    For example, if you compare the switching capacity of a HP 4108GL - 36.6 Gbps and compare this with a HP 2800 - 96 Gbps, even at the same 'connected' speeds, you're going to get much better transfer rates.

    In cabinets where you have 3 or 4 switches, I'd recommend replacing them with a single 48 port switch if you haven't already. I also find sticking with the same brand - HP or Cisco can also make all the difference and keeps managing the network straight forward.

    Eventually OM3 will be the standard, but as you say it's still very expensive. You can actually run 10Gb on very short OM2 links if you want to save some cash. Alternatively CAT6 upto 55m will support 10Gb too. Any new fibre links should be OM3, but OM1 still has a lot of life left in it

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    We have 2x 10GB/s links from out core to our English/IT and Science near edge switches (where most the traffic goes). this has a 1GB/s failover on OM3.
    Everything else has 2x1GB/s link on OM2 or copper.

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    Thanks everyone for all of the posts, much appreciated. It's really good to see what people with set-ups similar to us have done. Our monitoring hasn't been to good, we've recently installed Cacti and Nagios and are trying to get it working.

    We run a creative and media diploma so there is lots of streaming video, large downloads going across the network. Our media suite was very slow because we had a single 1gb OM1 fibre serving 4 HP Procurve switches, mostly 48 port models. Running 3 CAT5E cables to the other 3 switches in the cabinet has helped significally.

    Something else we're thinking about is getting a whole school fast wireless solution. I have thought about having all AP's wired straight back to the core switch to provide maximum speed....where within the 100M radius. This does seem a 'messy option' though but would surely provide the fastest speed and no work other than purchasing for example 2 X 24 port GB modules for our HP 4108GL and the actual physical cabling would be required. Dong it the traditional way of just having the AP points wired back the nearest cabs wouldn't be quick enough with our current set up.

    I need to do some thinking, lots of options, upgrade the core switch, get better links to the feeder cabs, AP's back to the core switch, etc.

    Thanks again...keep the responses coming!
    Last edited by ronnoco; 23rd June 2011 at 08:25 PM.

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    We run a creative and media diploma so there is lots of streaming video, large downloads going across the network. Our media suite was very slow because we had a single 1gb OM1 fibre serving 4 HP Procurve switches, mostly 48 port models. Running 3 CAT5E cables to the other 3 switches in the cabinet has helped significally.
    Other options to consider are strategically placed NAS boxes, either with SAS or SSD drives (if it exists). I don't think I've seen a NAS with SSD drives, or you could create one?

    If you're already running 48 port switches, then you could look at trunking or bite the bullet and just get OM3 installed. There's certainly justification if you have plenty of video files moving across the network.

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    IanT's Avatar
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    Every HP switch in my place has 2x 1Gb Link\trunk to a switch, everything is running on CAT6 with OM3 Fiber.

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