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Switch port is in errdisable status due to a duplex mismatch



The errdisable status indicates that the port was automatically disabled by the switch operating system software. This occurred because of an error condition encountered on the port. 

To resolve this issue, perform these steps:

  1. Determine if a port is in errdisable status by issuing the show port command. For example, to check the status on port 3/2, issue the show port 3/2 command.

    This is a sample command output:

    Cat5500> (enable) show port 3/2
    Port  Name               Status     Vlan       Level  Duplex Speed Type
    ----- ------------------ ---------- ---------- ------ ------ ----- ------------
    3/2                      errdisable 1          normal   auto  auto 10/100BaseTX

    The switch sends a message to the console describing why the port was disabled when it puts a port in the errdisable state. If the syslog is configured, the message will be available on the syslog server as well.

  2. Another way to determine the reason for errdisable status is to issue the show errdisable-timeout command. This command is available in Catalyst OS (CatOS) version 5.4(1) or later.

    This is a sample output:

    Cat5500> (enable) show errdisable-timeout
    ErrDisable Reason   Timeout Status
    ------------------- --------------
    bpdu-guard          disable
    channel-misconfig   disable
    duplex-mismatch     enable
    udld                disable
    other               disable

    Interval: 30 seconds

    Port ErrDisable Reason
    ---- -----------------
    3/2   duplex-mismatch
  3. If a duplex mismatch is the reason for the errdisable status, check these settings:
    1. Verify that the speed and duplex settings are the same on the switch port and the connected device. To display the speed and duplex settings on the switch port, issue the show port command. Hard set both sides to the same settings if possible.
    2. To hard set the duplex on the port, issue the set port duplex command. For example, to set the duplex on port 3/2 to full, issue the set port duplex 3/2 full command.
    3. To hard set the speed to 100 on the same port, issue the set port speed 3/2 100 command.
    4. Verify that the Network Interface Card (NIC) supports the speed and duplex settings required and that the NIC drivers are up to date.
  4. Once the cause of the duplex mismatch has been found and corrected, reenable the port by issuing the set port enable command. For example, to reenable port 3/2, issue the set port enable 3/2 command.

If the set port enable command is issued without the cause of the errdisablestatus being corrected, the port will eventually go back to errdisable status.

For more information on the errdisable port status, refer to Recovering From errDisable Port State on the CatOS Platforms.