spanning-tree (PVST)-root bridge change

Discussion in 'Cisco' started by koh, Mar 18, 2010.

  1. koh

    koh Guest

    Hi,

    Can anyone tell me the reason for the following ?
    There are 4 switches which is running spanning-tree (PVST).
    I turned off spanning-tree for the root bridge,but nothing happened
    except that another switch became root bridge.

    thanks in advance
    koh, Mar 18, 2010
    #1
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  2. koh

    KrisJun

    Joined:
    Feb 19, 2010
    Messages:
    2
    this is normal behavior, when you disable stp on your root bridge the other switches in the spanning tree will start an election process to determine the new root bridge which probably is the switch with the lowest MAC adress (unless you configured priority).

    if you want to get rid of stp you will need to disable it on all switches. If you want to control who becomes root bridge you need to set a lower spanning tree priority for that particular bridge and preferably select a second switch to become the backup of root (in case it fails) by configuring a higher priority then the root but lower then the default value ( 32768 )

    However, it is not recommended to turn of spanning tree unless you really know what you are doing. A slight configuration mistake can result in a loop causing your entire network to fail
    KrisJun, Mar 18, 2010
    #2
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  3. koh

    Jovan Yeo Guest

    On Mar 18, 5:10 pm, koh <> wrote:
    > Hi,
    >
    > Can anyone tell me the reason for the following ?
    > There are 4 switches which is running spanning-tree (PVST).
    > I turned off spanning-tree for the root bridge,but nothing happened
    > except that another switch became root bridge.
    >
    > thanks in advance


    did u do a sh spanning tree?check yr configuration.
    Jovan Yeo, Mar 18, 2010
    #3
  4. koh

    bod43 Guest

    On 18 Mar, 09:10, koh <> wrote:
    > Hi,
    >
    > Can anyone tell me the reason for the following ?
    > There are 4 switches which is running spanning-tree (PVST).
    > I turned off spanning-tree for the root bridge,but nothing happened
    > except that another switch became root bridge.
    >
    > thanks in advance


    Well what would you like to happen? :)

    Depending on your network topology it is quite possible
    that even with STP off on one or more switches that the
    network will still operate correctly or even optimally.

    If you post the topology (ASCII art or maybe a link to a
    diagram somewhere) then maybe someone will come
    up with some firm suggestions.

    I forget whether with STP off cisco switch are transparent
    to BPDUs or if they block them. Well I have never turned
    STP off.
    bod43, Mar 19, 2010
    #4
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