spanning tree portfast

Discussion in 'Cisco' started by ants, Mar 9, 2005.

  1. ants

    ants Guest

    we have all the ports set to "spanning-tree portfast".
    on some desks we have a shortage of data ports hence mini hubs and
    smaller switches have been installed.
    Is this likely to cause problems with network loops?
    thanks
    ants, Mar 9, 2005
    #1
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  2. ants

    Scott Ware Guest

    Usually, Yes. Cisco does not recommed enabling portfast on uplink ports
    (ones that have switches, hubs attatched to them).

    I would recommend that you turn off spanning-tree portfast on all of
    your ports that are connecting to other network devices.
    Scott Ware, Mar 9, 2005
    #2
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  3. ants

    Guest

    On 9 Mar 2005 03:27:49 -0800, "ants" <> wrote:

    >Is this likely to cause problems with network loops?


    If you have portfast enabled on every port and your users have access
    to hubs then there is a higher chance that loops occur. It would only
    take a second connection from your switch to the same hub and you have
    a loop.

    A loop is not a local problem because it could affect the your whole
    spanning tree because the affected router is too busy with it's loop
    which in turn could cause new loops, even in other vlans.

    Better protect the users against themselves. It's not worth the risk.
    Also, with portfast and a hub you only save yourself 30 seconds when
    you connect a hub which is connected anyway all the time.

    Cheers,

    Danny
    , Mar 10, 2005
    #3
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