Stacking 3550s with Gigastack

Discussion in 'Cisco' started by Johnny Noitargim, Oct 2, 2004.

  1. Hi everyone,

    I currently have a couple 3548s connected in pairs with the gbic module. I
    read that if you add a third one (all the way to 9) the duplex will drop to
    half unless I utilise the 3550 12G aggregator which will give me 2GB full
    duplex.

    My question is: is this limitation applied to all gbic modules (fibre, sx,
    zx, etc) or just the gigastack. (or are the fibre, etc. modules not meant
    for stacking?)

    TIA,

    Johhny
     
    Johnny Noitargim, Oct 2, 2004
    #1
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  2. :My question is: is this limitation applied to all gbic modules (fibre, sx,
    :zx, etc) or just the gigastack. (or are the fibre, etc. modules not meant
    :for stacking?)

    sx, lx, lh, zx are not meant for stacking. You can -chain- devices
    with them, which will use up one of the 7 hops allowed in Spanning Tree
    resolution. When you -stack-, the stacked devices would work together.
     
    Walter Roberson, Oct 2, 2004
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  3. Johnny Noitargim

    Darren Green Guest

    Is it not true that if you actually use 2 x gigastacks in the second switch
    (i.e. 1 to connect to the top switch and a second to connect to the switch
    below) you achieve full duplex. I am sure that I read this somewhere.
    Perhaps someone could confirm / deny.

    Regards

    Darren
     
    Darren Green, Oct 2, 2004
    #3
  4. Johnny Noitargim

    Mirko Kulpa Guest

    Yes, the links work with full duplex.


    Mirko
     
    Mirko Kulpa, Oct 2, 2004
    #4
  5. Hi,

    Gigastack modules will only work in half-duplex mode when both of the
    connectors on the gigastack gbic are used. So if you use two gigastack
    modules in one switch, both only using 1 connector, you'll end up with full
    duplex links. But that's not what these modules are designed for. They're
    designed to work with both connectors connected (create a ring-structure,
    with one link in standby mode (stp), on all switches in the stack).
    Ex. all switches have 1 gigastack module: Switch A->B, B->C, C->D, D->A (and
    you'll end up with half-duplex connections).

    Erik
     
    Erik Tamminga, Oct 3, 2004
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