Strange little problem with duplex on Cisco 3550

Discussion in 'Cisco' started by Geert, Feb 18, 2004.

  1. Geert

    Geert Guest

    Anyone noticed problems saving the duplex settings of ports on catalyst
    3550 switches, running 12.1(14)EA1a

    We can configure duplex settings via CLI, but "show running-config" does
    not show the duplex setting (???). When configuring the same port via
    Cisco Cluster software, the setting is saved (and is visible in cli config)

    Bizar.......

    mvg,
    Geert
     
    Geert, Feb 18, 2004
    #1
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  2. Geert

    chris Guest


    When doing it from the CLI, are you doing a 'shut' then 'no-shut'?
    You can't really change duplex on the fly - you have to bring the link
    down and renegotiate with the client.

    -Chris
     
    chris, Feb 19, 2004
    #2
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  3. Geert

    Geert Guest

    Haven't done that. I'll give it a try, THX.......
     
    Geert, Feb 19, 2004
    #3
  4. Geert

    Geert Guest

    Haven't done that. I'll give it a try, THX.......
     
    Geert, Feb 19, 2004
    #4
  5. Geert

    Geert Guest

    Haven't done that. I'll give it a try, THX.......
     
    Geert, Feb 19, 2004
    #5
  6. Geert

    Geert Guest

    Haven't done that. I'll give it a try, THX.......
     
    Geert, Feb 19, 2004
    #6
  7. Geert

    AnyBody43 Guest


    A couple of things here.

    I am not 100% sure on this but here goes anyway...

    1.
    IIRC when I have changed the duplex settings the port does
    go down and then comes back up automatically. No shut - no shut
    needed.

    2.
    In common with all cisco IOS configs there are default settings that do
    not appear in the config.

    prompt#sh run
    ....
    !
    interface FastEthernet0/3
    spanning-tree portfast
    !
    ....

    prompt#sh int fa 0/3
    FastEthernet0/3 is up, line protocol is up
    ....
    Auto-duplex (Full), Auto Speed (100), 100BaseTX/FX
    ....

    So I have a duplex setting (Auto, the default) but nothing in the
    config.

    That a default should appear in the config under some circumstances
    is not entirely unknown either, a new router has a few things in
    the config that are defaults.


    Is "no service pad" an example?

    Maybe the GUI thingy is bypassing the (is this a default)
    test. Would not worry me too much.


    If you are setting non default values then of course that is a
    different matter. In that case, more details please.
     
    AnyBody43, Feb 19, 2004
    #7
  8. Geert

    Geert Guest




    Indeed, i am setting a copper 10/100/1000 port of a Cisco 3550 switch to
    1000 bps fixed full duplex. So this is definetly not the default.

    I just follow normal procedure:
    CLI
    Interface Config mode
    speed 1000
    duplex full
    exit


    when i do a show running config,
    speed is OK, but there is no line for duplex

    when verifying with Cluster Manager, the port is still in auto duplex
    mode ?????????

    IOS (tm) C3550 Software (C3550-I5Q3L2-M), Version 12.1(14)EA1a, RELEASE
    SOFTWARE
     
    Geert, Feb 20, 2004
    #8
  9. Geert

    chris Guest


    Gigabit is always full-duplex on all 4 pairs, so trying to force a
    duplex setting is irrelevant.

    -Chris
     
    chris, Feb 21, 2004
    #9
  10. Geert

    Geert Guest

    There still is a difference between CLI and CM and that confuses the
    customer.
    When doing

    speed 1000
    duplex full

    in CLI, only speed is recorded, there is no line for duplex (could be
    the default as you mentioned)

    BUT

    When setting the speed to 1000 and duplex to full via GUI of Cluster
    Manager and then doing a sh running-config,
    you get speed line AND a duplex line in the running-config (???):

    speed 1000
    duplex full

    This is probably a bug, since there are no problems and/or differences
    noted in production.

    -Geert
     
    Geert, Feb 21, 2004
    #10
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