Catalyst 2950 Amber light question

Discussion in 'Cisco' started by John, Sep 16, 2004.

  1. John

    John Guest

    Hello gang:

    The other day, I was rewiring something and I noticed an amber light
    in one port of my 2950, after investigating I found out that it
    stopped forwarding because maybe it detected a loop and disabled by
    STP?

    Anyway, it brought down that port and activated the one new cable I
    plugged in. The network went down for a little bit then came up, I
    suppose it was now using the new cable.

    Is there a way to overcome this? I don't want to bring the network
    down just because the Catalyst detected a loop in the network, maybe
    if it sees two links to the same upstream hub, it shoud load balance?

    Any help, suggestion, education is greatly appreciated!

    TIA

    J.
    John, Sep 16, 2004
    #1
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  2. "John" <> wrote in message
    news:...
    > Hello gang:
    >
    > The other day, I was rewiring something and I noticed an amber light
    > in one port of my 2950, after investigating I found out that it
    > stopped forwarding because maybe it detected a loop and disabled by
    > STP?
    >
    > Anyway, it brought down that port and activated the one new cable I
    > plugged in. The network went down for a little bit then came up, I
    > suppose it was now using the new cable.
    >
    > Is there a way to overcome this? I don't want to bring the network
    > down just because the Catalyst detected a loop in the network, maybe
    > if it sees two links to the same upstream hub, it shoud load balance?
    >
    > Any help, suggestion, education is greatly appreciated!
    >
    > TIA
    >
    > J.


    Spanning tree is supposed to work this way... if you want 2 physical links
    between switches you should channel them.

    BL
    --
    There is nothing more frightening than ignorance in action. - Goethe
    Buzz Lightbeer, Sep 16, 2004
    #2
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  3. John

    John Vo Guest

    "Buzz Lightbeer" <> wrote in message
    news:4149cbfd$0$20247$...
    > "John" <> wrote in message
    > news:...
    >> Hello gang:
    >>
    >> The other day, I was rewiring something and I noticed an amber light
    >> in one port of my 2950, after investigating I found out that it
    >> stopped forwarding because maybe it detected a loop and disabled by
    >> STP?
    >>
    >> Anyway, it brought down that port and activated the one new cable I
    >> plugged in. The network went down for a little bit then came up, I
    >> suppose it was now using the new cable.
    >>
    >> Is there a way to overcome this? I don't want to bring the network
    >> down just because the Catalyst detected a loop in the network, maybe
    >> if it sees two links to the same upstream hub, it shoud load balance?
    >>
    >> Any help, suggestion, education is greatly appreciated!
    >>
    >> TIA
    >>
    >> J.

    >
    > Spanning tree is supposed to work this way... if you want 2 physical links
    > between switches you should channel them.



    Hi all:

    Thanks for the info. I read some stuff on Cisco website about EtherChannel.
    My question is: My provider is giving the pair from a "Cisco Box" will I
    still
    be able to do EtherChannel? does it have to be from another Catalyst Switch?

    Thanks,
    J.
    John Vo, Sep 18, 2004
    #3
  4. John

    Guest

    On Sat, 18 Sep 2004 22:07:13 GMT, "John Vo" <> wrote:

    >
    >"Buzz Lightbeer" <> wrote in message
    >news:4149cbfd$0$20247$...
    >> "John" <> wrote in message
    >> news:...
    >>> Hello gang:
    >>>
    >>> The other day, I was rewiring something and I noticed an amber light
    >>> in one port of my 2950, after investigating I found out that it
    >>> stopped forwarding because maybe it detected a loop and disabled by
    >>> STP?


    What did the log on the switch say? "show interface" or "show
    spanning-tree" should give yu a give clue as well.


    >>> Anyway, it brought down that port and activated the one new cable I
    >>> plugged in. The network went down for a little bit then came up, I
    >>> suppose it was now using the new cable.
    >>>
    >>> Is there a way to overcome this? I don't want to bring the network
    >>> down just because the Catalyst detected a loop in the network, maybe
    >>> if it sees two links to the same upstream hub, it shoud load balance?


    Would you rather bring down the network for a longer period of time
    due to the loop?


    >>> Any help, suggestion, education is greatly appreciated!
    >>>
    >>> TIA
    >>>
    >>> J.

    >>
    >> Spanning tree is supposed to work this way... if you want 2 physical links
    >> between switches you should channel them.


    Or if you're happy with just a redundant link, let spanning-tree do
    it's job. That's what it was originally designed for. The loop
    prevention was a beneficial side-effect. You might also consider
    setting some of the other options so that it prefers one link over the
    other and protects your uplink (rootguard). For the host connections,
    spanning-tree portfast is almost essential if you run dhcp.

    >
    >Hi all:
    >
    >Thanks for the info. I read some stuff on Cisco website about EtherChannel.
    >My question is: My provider is giving the pair from a "Cisco Box" will I
    >still
    >be able to do EtherChannel? does it have to be from another Catalyst Switch?



    Generally, yes you'll need the same manufacturer. In your case, I
    believe you can do etherchannel with most of the newer Cisco switches.
    If you are trunking and using multiple vlans, you can assign specific
    vlans to each trunk.
    , Sep 19, 2004
    #4
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