Answered Managed Switch - Home Network

Discussion in 'Networking & NAS' started by Violator, Feb 2, 2018.

  1. Violator

    Violator
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    Is it worth it? I have 3 switches around the house at the moment, on a gigabit network. I'm away to update my NAS to one that supports Link Aggregation and it's something that only comes on managed switches.

    So question(s) :

    1. Is Link Aggregation worth it?
    2. If you have a managed switch in your network, do the others (or is it better) need to be managed?

    Ta muchly :)
     
  2. Best Answer:
    Post #2 by mickevh, Feb 2, 2018 (1 points)
  3. mickevh

    mickevh
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    Best Answer
    1:

    Link Aggregation is certainly "worth it" in the right use case: It's "more lanes on the motorway" not "faster speed" so in a SOHO use case, where traffic levels are low, very "bursty" and between a relatively small numbers of device pairings, one might argue "it's not worth it."

    Others here have reported that LA has given them greater "speed" - say with 2 x 1GBit links in an LA, to turn a 1GBit link into a 2GBit link, but I'm a little skeptical about that as I've never seen it happen in enterprise kit of my experience, and I can argue a whole load of reasons why it is unlikely to happen. However, I am not there to witness those that say having deployed an LA pathway between device X and Y they watched their "speed" leap up, so I can only take them at their word that with their LA equipment mix, it did indeed deliver a speed increase,

    Incidentally, LA's aren't limited to 2 physical links, they can contain more if you have hardware that's capable. The max. I've seen is 8.

    Bear in mind that an LA only "works" between the devices either end of any given physical (LA) link - ie the pair of devices either end of a bundle of network cables. If you want endstation-to-endstation LA, then everything has to be up to it.

    For example, N=NAS, S=Switch, C=client (let's presume all NIC's are GBit for the purposes of debate) and "=" means 2x1Gbit LA, and "-" means "normal" single link GBit

    N---S---C is a nice end to end GBit link.

    You could do this:

    N===S---C and you certainly have an LA, but "C" wouldn't notice any difference as it's S---C is still GBit. The benefit of LA in this scenario is that the N===S link could service a second client at GBit concurrently. Or a 8-10 100mbps clients. etc. etc.

    To truely get a 2GBit endstation to endstation link you'd need this:

    N===S===C ie, "C" need's 2 NICs and LA capability. Even then, there's factors to consider such as whether the OS in N and C can/would take advantage of the bandwidth. "Out of order packet delivery" is a bit of a nemesis in data networking, and much is designed to avoid it: Filling up both paths in an LA (ie "a-b"ing the packets in a stream across an LA) would encourage OOPD and much networking is designed to avoid it. Incidentally, in this scenario, you have two LA's - one N===S and one S===C which both function independently and unaware of each other. LA is a point-to-point technology, not an endstation-to-endstation one.

    It's kind of like choosing which Q/till to join at the supermarket checkout. Imagine that instead of individual clients, we arrive at the checkout in "trains" of 5-10 (or whatever) customers, but having chosen a Q/till, every train member uses the same Q/till. If there's only one Q, well we all rattle through in big line and if it's busy, we're subject to congestion. But if there's multiple Q/tills, we can pick the one that looks "best." More Q/tills means more "trains" can be processed concurrently (giving better throughput for any given customer,) but the rate of progress of any particular train through any particular Q/till is just the same. What we don't do (because it's "the rules") is break up the train and "spread" it across multiple tills, because when we get "the other side" we're got to go through a whole load of grief reassembling the train back into order and fully constituted before we can shuffle off to the bus stop. (In real data networks, it's not quite like that - it's the receiving end station that has to do the reassembly.)

    2:

    Do other switches need to be managed, no. Is it "better" - well "better" in what way..? Again, I'm afraid "it depends" on your use case. But for sure, unmanaged switches almost certainly don't do LA.

    You pays your money...

    EDIT 2018: I was reading a presentation on IEEE standard LA recently and noticed that the IEEE standards mandate that the an LA must not result on out of order packet delivery at the receiving end to an LA. (Incidentally, and must not add any extra bits to the packets as they transit the link.)
     
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    Last edited: May 3, 2018
  4. Violator

    Violator
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    Thanks @mickevh very informative answer :)
     

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