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Recovering from ErrDisabled port due to misconfiguration

Introduction:

The ErrDisable feature is implemented to handle special situations where the switch detected excessive or late collisions on a port, port duplex misconfiguration, EtherChannel misconfiguration, Bridge Protocol Data Unit (BPDU) port-guard violation, UniDirectional Link Detection (UDLD), and other (miscellaneous) causes.

 

The error-disable function allows the switch to shut down a port when it encounters physical, driver or configuration problems. A port being error-disabled is not by itself a cause for alarm, but a symptom of a problem that must be resolved.

Troubleshooting an ErrDisable Port on the CatOS Platforms:

 Determine cause of ErrDisable error on the port. For example, a show port might indicate a parameter mismatch of EtherChannel.

 

 

    In this case, it was err-disable due to channel-misconfig.

 

    Fix identified ErrDisable cause (for example, match parameters on either end of link).

 

    After fixing cause of problem , the port will still be disabled (and the port LEDs are still orange). Re enable the port manually by entering set port    enable.

 

For further symptoms, root causes, and solutions for an ErrDisable port, refer to Recovering From errDisable Port State on the CatOS Platforms.

 

Troubleshooting an ErrDisable Port on the IOS Platforms:

 

When a port is in error-disabled state, it is effectively shut down and no traffic is sent or received on that port. The port LED is set to the orange color and, when you issue the show interfaces command, the port status shows as Errdisabled.

Following is an example of what an error-disabled port looks like:

switch#show int G1/0/1

GigabitEthernet1/0/1 is down, line protocol is down (err-disabled)

To find out the main reason for err-disable state. In our case it is port security violation on port Gi1/0/1.

switch#show interfaces status err-disabled

Port      Name               Status       Reason

Gi1/0/1  SERVER01    err-disabled psecure-violation

Gi1/0/46                     err-disabled psecure-violation

Gi2/0/12                     err-disabled psecure-violation

 

To recover a port that is in an Errdisable state, manual intervention is required, and the administrator must access the switch and configure the specific port with 'shutdown' followed by the 'no shutdown' command. This command sequence will enable the port again, however, if the problem persists expect to find the port in Errdisable state again soon.

 

Fix port configuration:

Switch#conf t

Switch(config)#int G1/0/1

Switchconfig-if)#shut

Switchconfig-if)#no shut

you may not want a port with a security violation to come back up without administrative intervention, but a port downed due to a flapping host you might want automatically turned back on after a few minutes. You can issue the "errdisable recovery cause" command to configure and see a list of switch port errors that the switch can automatically recovery from.

 

In the below example setting Errdisable autorecovery for BPDU GUARD.

The second option you can configure is the time  interval in which the switch waits before it re-enables the err-disabled port. The default recovery interval is 300 seconds.

 

 

While this err-disable recovery feature can be a great time saver it is still important to investigate and correct the real issue that is causing the switch ports to fail into an err-disabled state.

Related Information:

Errdisable Port State Recovery on the Cisco IOS Platforms

Version history
Revision #:
1 of 1
Last update:
‎06-22-2009 04:39 PM
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