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Wired Networks Thread, Upgrading to Gigabit for end users - a question regarding fibre links... in Technical; We've had a bit of an audit by some colleagues from a neighboring school and one of the recommendations is ...
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    Upgrading to Gigabit for end users - a question regarding fibre links...

    We've had a bit of an audit by some colleagues from a neighboring school and one of the recommendations is to upgrade our fairly elderly core switch. This device has some ethernet ports which would then benefit by an upgrade to gigabit, but it also has gigabit fiber links to the other switches around site. We would also then upgrade these other switches so that they could provide gigabit speeds via copper to the end user. Once upgraded as per the recommendation we'd have a situation where the switches are linked by gigabit fiber to the core switch, but are then also connecting to the end user by gigabit copper.

    I can't quite reconcile how this would work - unless I'm missing something it would seem that we'd see no benefit at all up until the point where the fiber link becomes the bottleneck between core switch and end user. Upgrading the core switch would also allow us to increase capacity in future (site-wide wifi infrastructures are planned, for example), but it seems to me we'd need to upgrade the fiber links between switches to 10 gigabit or start pairing them to improve performance, or leave the switches around site as they are.

    Any thoughts?

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    localzuk's Avatar
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    In my experience, gigabit to the end user is mostly unnecessary still. In terms of bottlenecks, switches generally divide up bandwidth equally - so if 10 users connect and demand something heavy, they'll each get 100Mbit of that 1Gbit uplink.

    It is entirely possible for those 1Gbit uplinks to become bottlenecks, but in my experience monitoring various networks, its highly unlikely to happen in a school unless you're having classes filled with people editing HD video over the network... If that's the case, you want 10Gbit uplinks.

    If I were to do a network upgrade here (100Mbit to desktop, 1Gbit backbone links), I would be going 1Gbit to desktop and 10Gbit to each switch. The cost of doing so would be relatively minimal compared to going 1Gbit/1Gbit everywhere. We'd have to replace 2 lengths of fibre cable entirely, but out of the 14 or so links, that's not going to be a huge percentage of the cost.
    Last edited by localzuk; 19th March 2014 at 01:57 PM.

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    IrritableTech's Avatar
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    We do run gigabit to the desktop here, but as @localzuk says it's largely unnecessary. Due to old OM1 fibre links, we can only interlink switches in trunks of two gigabit fibres.

    Looking at my monitoring tool right now - the most utilised trunk is running at 56/72Mbps. Looking at the history - it hasn't broken 100mbits today. The link has about 100 pc's running on it, plus printers and wireless devices (~30).

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    Hmm.. My concern is that the recommendation we have been given would result in an enormous amount of money to be spent, and I want to be sure its necessary! I think the core switch recommendation holds water - its not getting any younger, there is only space for one more module and doing anything involved gigabit ethernet would be difficult I think... But can't quite see the point in upgrading the out lying switches just yet.

    @IrritableTech - what monitoring tool are you using, out of interest?

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    We do gigabit to the desktop here but only because the new end switches we standardise on are 48 port Gigabit. Basically when we upgrade a cabinet - users happen to gain gigabit to the desktop as a byproduct. We have 12- 48PCs per 1Gig fibre uplink, so the uplink to core switch is always the bottleneck, only way round that is 10Gig uplinks, fairly cheap if you'ge got short runs of Cat6e like some schools, VERY expensive if you've got 30 old runs of fibre that are probably not 10gig capable, like me!

    Gigabit to desktop is not a reason, in itself, to upgrade. Your much more likely to be bottlenecked by the PCs themselves, or the uplinks, rather than each PCs actual network connection. (that is, unless your entire school is based around Dual CPU video editing stations saving terrabytes of video to large scale superfast storage arrays?).
    Last edited by AButters; 19th March 2014 at 03:07 PM.

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    IrritableTech's Avatar
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    Quote Originally Posted by cheredenine View Post
    @IrritableTech - what monitoring tool are you using, out of interest?
    I'm just using 'The Dude' by Mikrotik.

    Our last set of switches lasted ten years, hopefully these will do the same. Much like @AButters we wanted to standardise our switches as much as possible. Our 5412ZL feeds 2910AL's which each feed 2510's The idea is that if we found money to replace our fibre, both the 5412 and 2910's could all be upgraded to 10Gbit. I expect now we'd be probably be replacing before upgrading them.

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    Boredguy's Avatar
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    Our 10 fibre links are limited to 1Gb, and we have 1Gb to the desktop for most rooms (Some switches are still only 100mb to the desktop but with 1Gb uplinks)

    We never hit more than 30mb over the fibre connections during the school day. The only one that exceeds 50mb on a regular basis is the connection that runs to the building hosting our backup server each night when it copies all the user and SIMS data.

    We are using Cacti to monitor all our switches.

    I am waiting for a company to quote me for replacing all our existing OM1 fibre for OM4 to give 10Gb but not heard yet (and I doubt we will hit our current capacity even when we plan on rolling out 1:1/BYoD for Sept 2015!)

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    AButters's Avatar
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    Quote Originally Posted by IrritableTech View Post
    I'm just using 'The Dude' by Mikrotik.

    Our last set of switches lasted ten years, hopefully these will do the same. Much like @AButters we wanted to standardise our switches as much as possible. Our 5412ZL feeds 2910AL's which each feed 2510's The idea is that if we found money to replace our fibre, both the 5412 and 2910's could all be upgraded to 10Gbit. I expect now we'd be probably be replacing before upgrading them.
    Yep as above our old 4100GL and 2650 / 2524 from HP lasted 10 years. Stuck with HP for the upgrade here, 5412ZL Core too 8x10GBE links available for servers in the cab and 24 x MiniGBIC with 1GB Fibre converters feeding a mix of 2530-48G PoE+ for busy areas, V1910-48G-PoE+ for less busy areas and V1910-48G & V1910-24G for curriculum network only areas.

    I've said it before and I'll say it again, HP are the best switches when you take into account the combination of value, performance, reliability. Other manufacturers have two of those three, HP is the only one that has all three.
    Last edited by AButters; 19th March 2014 at 03:46 PM.

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    @AButters:

    Can match and beat your 10 years by 2 and they still going strong:

    Core switch = WS-C3550-12G

    Edge switches a mixture of 3550's 48 ports 100MB and 3560's 48 port 100MB

    Fibre OM3 backbone with OM3 fibre upload links to all switches

    100MB to desktop

    Still going strong but looking to upgrade to either Juniper or Meraki (Cisco) all with POE and 10GB uplinks and 1GB ports plus 10GB backbone, this shouldn't be as expensive this time round with all OM3 fibre already in place but might (cost willing) change to OM4 to make it last another 12 or so years.

    Never thought about HP and just as well now with the cost of their support going up on all their kit, never needed support for our Cisco kit it just works.

    Happy Day's

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    Upgrading to Gigabit for end users - a question regarding fibre links...

    30 students saving a 100mb portfolio word file (with screenshots of their work throughout the year)

    Over a 1gbs link. How long does it take to save the file.

    Now make that 60 students.

    The case for 10gbsec to the core and servers rests m'lud.
    Last edited by psydii; 19th March 2014 at 05:12 PM.

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    It is worth considering what data sources will be accessing via the switches as your storage throughput could be the bottleneck if you have 10gb backbone to all switches.

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    Om3 will take 10gb over certain distances.

    My old school ran hp and I did like it. Good kit. I didn't like the V models as they are 3com rebrands since hp bought 3com. Check the warranty, 3 yrs vs lifetime.

    I currently use extreme switches (can't recommend high enough!) we have 1gb to the desktop and 10gb backbone for the most.
    The 1gb to the desktop is not the main concern for me it's the increase in wifi and n / AC you really need 1gb to he aps. And with this the 10gb back haul.

    I currently have around 3 links which transmit at over 300mb/s each day. Now I know this isn't over the 1gb/s link and you could choose to install 8/16 core fibre and use trucked 1gb links to provide 2/3/4 gb/s but eventually, 3, 5 years down then line you'll need 10gb/s.

    If you have to do an upgrade now you'd be wise to put some room for growth in place now.

    Just my 2c.

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    GeekyPete's Avatar
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    Phase it, Give a few key users GBit, maybe one ICT room. Then in 3 months time do a cost/benefit analysis. I guarantee most rooms you'll leave on 100Mbit. Most schools I deal with will never need Gbit, unless they release a gbit iPad!

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    Quote Originally Posted by cheredenine View Post

    Any thoughts?

    Ethernet is Ethernet, whether over copper or fiber. True, when you are talking about the big multi-gigabit links you're talking about fiber, but that's for back-haul.

    However, glass doesn't conduct electricity. Which is GOOD if you would prefer not to have a power surge come up the link and take out your switch, especially if it happens to be a 4507 or a 6509. It's BAD if you ever want to run PoE over the link.

    I like to see Fiber from the site's main switch to the cluster commander and then copper to the access switches.


    For example...
    Cisco 4503 <---2 or more Trunked Gigabit Fiber Links to each Cluster Commander---> Cisco 3750 PoE Switches <---1 or more 100 Megabit Cat5e links to each Access Switch---> Cisco 2960 Switch or 561AP's

    Now, the brand names and the models don't really matter. Plus, you can eliminate things you don't need. The parts that I think are worth remembering are to use copper at the access level so that you can carry Power over Ethernet, and segregate your access layer switches (either 802.3 or 802.11) from your higher level (more expensive) equipment with fiber optics.


    BTW, it was drilled into me years ago to never forget... An ether channel isn't 400 meg of bandwidth (100m each way, assuming full duplex, times two channels), it is TWO INSTANCES of 200 meg bandwidth. That really only matters once you get above two ports in an ether channel and then mainly in 3, 5, 6 & 7 port channels. So, not really something that should matter for you in a single school no matter how large. Still worth reminding ourselves of though.
    Last edited by ericscher; 20th March 2014 at 04:29 AM.

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    If you are going to buy a new Core Switch, I would make sure it is 10Gb capable so that you can eventually use 10Gb uplinks to your end point switches. Make sure the backplane supports this and that the switch can provide enough 10Gb SFP+ ports (modular) to do this in the future (e.g. If you have 8 end-point switches, ensure your core can handle at least that many SFP+ connections).

    Also, you might want to consider 10Gb to the servers before moving all end clients to 1Gb in a large environment. In a small environment it's not important, but if you have 500+ clients that can end up being your bottleneck also makes backup/restore ops much faster.

    If the end point switches aren't that old, you may be able to hold off for another 1-2 years on upgrading those and spread out the cash you have to spend upgrading the network. Unless this is likely to be your one and only shot at getting the money for a good long while.

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