SPANNING-TREE HELPPP

Discussion in 'Cisco' started by Lorenzo, Jul 31, 2004.

  1. Lorenzo

    Lorenzo Guest

    I have a redundant lan and then the STP breack the loop. And all is ok...

    But i need to change the NON-DESIGNATED PORT because i must put in BLOCKING
    state another port in another switch and not in the switch that STP have
    automatically chosen to block.

    In other words, How can I manually choose and set a port that I WANT in a
    switch that I WANT to become the BLOCKING port of the loop???

    I have tried changing the priority of the switch that I chosen to max
    (65535), then to changing of the port cost to max (65535) and the priority
    of port (255).
    But nothing, the STP don't choose my port to block and it continues to let
    it in FORWARDING state.

    Anyway, in general, what's the procedure to force manually a port to become
    the BLOCKING port of the loop? Did I try all or have I forgotten some
    procedures?

    Thanks a lot and sorry for my English

    p.s.
    It's probable that the problem derives from other causes because my lan is
    not very well configured, but I want know if I did all necessary procedures
    so that I know that the priorities of STP are ok and I can seek the problem
    in other parts.
     
    Lorenzo, Jul 31, 2004
    #1
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  2. Hola Lorenzo.

    Try Channing the Port Priority

    Read here to understand it:
    http://www.cisco.com/univercd/cc/td...cwsimain/cwsi2/cwsiug2/vlan2/stpapp.htm#39855

    Read here To configure it:
    http://www.cisco.com/univercd/cc/td...000/rel_5_2/config/spantree.htm#xtocid2879622



    Saludos,
    Victor Cappuccio
    www.vcappuccio.freeservers.com


    "Lorenzo" <> wrote in message news:<oEMOc.61236$>...
    > I have a redundant lan and then the STP breack the loop. And all is ok...
    >
    > But i need to change the NON-DESIGNATED PORT because i must put in BLOCKING
    > state another port in another switch and not in the switch that STP have
    > automatically chosen to block.
    >
    > In other words, How can I manually choose and set a port that I WANT in a
    > switch that I WANT to become the BLOCKING port of the loop???
    >
    > I have tried changing the priority of the switch that I chosen to max
    > (65535), then to changing of the port cost to max (65535) and the priority
    > of port (255).
    > But nothing, the STP don't choose my port to block and it continues to let
    > it in FORWARDING state.
    >
    > Anyway, in general, what's the procedure to force manually a port to become
    > the BLOCKING port of the loop? Did I try all or have I forgotten some
    > procedures?
    >
    > Thanks a lot and sorry for my English
    >
    > p.s.
    > It's probable that the problem derives from other causes because my lan is
    > not very well configured, but I want know if I did all necessary procedures
    > so that I know that the priorities of STP are ok and I can seek the problem
    > in other parts.
     
    Victor Cappuccio, Aug 1, 2004
    #2
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  3. In article <oEMOc.61236$>,
    Lorenzo <> wrote:
    >I have a redundant lan and then the STP breack the loop. And all is ok...
    >
    >But i need to change the NON-DESIGNATED PORT because i must put in BLOCKING
    >state another port in another switch and not in the switch that STP have
    >automatically chosen to block.
    >
    >In other words, How can I manually choose and set a port that I WANT in a
    >switch that I WANT to become the BLOCKING port of the loop???
    >
    >I have tried changing the priority of the switch that I chosen to max
    >(65535), then to changing of the port cost to max (65535) and the priority
    >of port (255).
    >But nothing, the STP don't choose my port to block and it continues to let
    >it in FORWARDING state.
    >
    >Anyway, in general, what's the procedure to force manually a port to become
    >the BLOCKING port of the loop? Did I try all or have I forgotten some
    >procedures?


    Setting the switch root priority to max forces the switch to be root
    which in turn forces all its links to be unblocked. For a link to
    be blocked, it must be a higher cost path to the root switch. So
    if the switch is root, it is up to the switch(es) at the other end
    of the link to decide that the path is higher cost and block it.

    Be very careful of randomly assigning root priority and port costs
    without first understanding how STP works. You really want to have a
    clear idea of not only what your desired default spanning tree should
    be, but also how that spanning tree will be negotiated and how you
    want it to adjust as various devices/links fail. Then you can assign
    root priorities and port costs to implement that plan. Otherwise,
    in a complex multiply connected LAN, it is possible to wind up with
    an unstable network which (literally) can take forever to converge
    after a topology change if traffic is heavy.

    Good luck and have fun!
    --
    Vincent C Jones, Consultant Expert advice and a helping hand
    Networking Unlimited, Inc. for those who want to manage and
    Tenafly, NJ Phone: 201 568-7810 control their networking destiny
    http://www.networkingunlimited.com
     
    Vincent C Jones, Aug 1, 2004
    #3
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