anyone know about: vlan trunking with catalyst 1900 to any other iosdevice (catalyst 2950)

Discussion in 'Cisco' started by Neddy, May 21, 2009.

  1. Neddy

    Neddy Guest

    Ok, i have about 200 catalyst 1900's on my network all running
    enterprise software...
    Basically i want to start vlanning them to a centralised point where i
    can route traffic thru a server running a web portal (but that's
    another story)...

    Basically i'm wondering if anyone has any experience with ISL vlan
    trucking from a catalyst 1900 - to any IOS enabled device also using
    ISL.. (In my case a Catalyst 2950) ... i can't use 802.1q as the
    catalyst 1900 only supports ISL trunking.

    I'm having issues with the guide cisco have put up over at:

    Firmware versions:
    Catalyst 1900's are all running 'Enterprise Edition Software' v9.00.06
    (WS-C1924-A or WS-C1924-EN)
    Catalyst 2950's are running 'Desktop Switch Software 12.1(11)EA1'

    Cheers in advance.
    Neddy, May 21, 2009
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  2. It will be difficult to find somewhat recent Cisco device supporting
    ISL. I don't remember out of top of my head, but 6500 series could be
    the only option left.

    Andrey Tarasov, May 21, 2009
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  3. And the 2950/2960 only supports 802.1q trunking, ISL has been dropped
    out of almost all of Cisco's product line for modern gear.

    You could get some Catalyst 2924xl's for cheap, they would do ISL trunking.
    Although you say you have 200 devices, you have to watch out for
    Cisco's STP instant limits, which hard limit the number of VLANs you
    can run through devices. Ie. the 2924XL has a max STP instance of 64,
    which means you can't break out or even trunk more than 64 VLANs through them.

    Otherwise, you'd have to step up to something like a 4500 or 6500 for
    the central point with whatever Sup engines support what you need. A
    basic 4500 with Sup IV will get you 1024 STP instances, and support
    ISL trunking.
    Doug McIntyre, May 21, 2009
  4. Neddy

    Neddy Guest

    I actually just realised that I have two catalyst 6000 series with 2
    supervisor modules and one switching module (both are in centralised
    points that all the catalysts connect to ... all catalysts are
    connected via wireless back-hauls using a Motorola product called
    Is there anyway I could trunk from the catalyst 1900's to the 6000
    series, and then trunk the 6000 series to the 2950?? this would make
    life MUCH easier...

    Otherwise, could I trunk directly to the 6000 series, and ill put some
    servers in-line with the 6000 series for the web-portal...
    Neddy, May 21, 2009
  5. Neddy

    Neddy Guest

    I have two 6000 series catalysts?
    Neddy, May 21, 2009
  6. Yes, the 6500 can talk both ISL and 802.1q trunking. You don't have
    to preserve the trunking type throughout, you can mix them.
    Doug McIntyre, May 21, 2009
  7. Neddy

    Neddy Guest

    Do you know of or have any guides as to what to do (configuration
    wise) in this case?
    Sorry for my ignorance, I'm new to this.

    Neddy, May 21, 2009
  8. Neddy

    brink Guest

    The manuals should still be online on CCO. A few things to know/
    remember :

    - 1900's have a funny way of handling more than the max # of spanning
    trees. Preferably do not use VTP and set up manually, allow
    only the vlans required towards the 1900
    - ISL support in the 6xxx and other switches depends on the port ASICs
    not on the supervisor, check module type
    - there once was a nice hardware bug which caused occasional unicast
    (!) storms when using ISL trunks/channels between 6xxx's and 1900s.
    I don't remember the details but I had an interesting time finding out
    at the time ...

    apart from that, no reason why it shouldn't work. If you want to trunk
    via wireless verify it supports max size packets plus dot1q, try ping
    using largish packet size like 1500

    luck, Frans
    brink, May 25, 2009
  9. Doug McIntyre, May 27, 2009
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