err-disabled port reason

[mar74]

We have a switch stack of Catalyst 3750's. 3 of the ports were err-disabled. I did a show interface status err-disabled. Here is the output:

Port Name Status Reason
Fa2/0/41 err-disabled loopback
Fa3/0/33 err-disabled loopback
Fa3/0/41 err-disabled loopback

What caused the loopback and how do I prevent it?

Thanks for your help in advance!

 

[lambent]

hmm any hints from show log?
This is the first time I see this reason too.

 

[RookThis]

Not sure if this is related or not:

Troubleshooting Power over Ethernet Switch Ports

If a powered device (such as a Cisco IP Phone 7910) that is connected to a Power over Ethernet (PoE) switch port and is being powered by an AC power source loses power from the AC power source, the device might enter an error-disabled state. To recover from an error-disabled state, enter the shutdown interface configuration command, and then enter the no shutdown interface command. Another method to recover the interface from the error-disabled state is to have automatic recovery configured on the switch. The errdisable recovery cause loopback and the errdisable recovery interval seconds global configuration commands automatically take the interface out of error-disabled state after the specified period of time.

Use these commands, described in the command reference for this release, to monitor PoE port status:

* show controllers power inline privileged EXEC command
* show power inline privileged EXEC command
* debug ilpower privileged EXEC command

http://www.cisco.com/en/US/products...figuration_guide_chapter09186a00801f6167.html