Cisco 837 ethernet0 half-duplex

Discussion in 'Cisco' started by wxu3000, Apr 18, 2006.

  1. wxu3000

    wxu3000 Guest

    Hi, all,
    When I plug in a Cisco837 router into the swich, it gives me a
    warning message: CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on
    rnet0 (not half duplex).

    When I do a "sh interface ethernet0", it shows: "Full-duplex,

    The IOS is: 12.3(8). Is there anyway to change it to half duplex?

    wxu3000, Apr 18, 2006
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  2. wxu3000

    Merv Guest

    what switch are you plugging the router into and how is the port
    configured ?
    Merv, Apr 18, 2006
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  3. wxu3000

    Merv Guest

    find out if the switch is capable of 100-full or 10-full and set it

    otherwise on the 837 try

    ethernet 0
    speed 10
    duplex half
    Merv, Apr 18, 2006
  4. wxu3000

    bhalicki Guest

    I had the same problem on an 837 and 2950 switch. IIRC, setting the
    duplex to half and speed to 10, still resulted in CDP duplex mismatch
    error, or collisions. I remember reading something about a CDP bug, so
    I just disabled CDP on that port.

    ie (on 837)
    ethernet 0
    no cdp enable

    or (on switch)
    fastethernet 0/24
    no cdp enable
    bhalicki, Apr 18, 2006
  5. wxu3000

    wxu3000 Guest

    under interface ethernet 0, I could not set it to half duplex. have to
    disable cdp. it worked. thank you very much guys.
    wxu3000, Apr 18, 2006
  6. Hi, all,
    Rather than disable CDP completely, you can issue the command:

    no cdp log mismatch duplex

    which just prevents the router reporting these errors.
    john.stewart5, Apr 19, 2006
  7. wxu3000

    the_Muttster Guest

    I had the same issue. I fixed the speed on the 2950 end to 10Mbit/HD
    and it went away. A bit of reading on the Cisco site at the time led me
    to believe that the E0 port isn't full-duplex which is the bug. Rather,
    it's a virtual interface of the 4 Fa ports which aren't proper
    switchports unlike the 1800 series. Therefore, for simplicity, I treat
    it as a hub.
    the_Muttster, Apr 19, 2006
  8. wxu3000

    none Guest

    At half duplex collisions are OK and normal - if you see frame or other
    errors then you have a duplex mismatch.

    none, Apr 22, 2006
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