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Re-activating ports after Port-channel deactivation.

Hi everybody,

Had a bit of an issue yesterday - I was running etherchannel in the lab and decided to convert the ports back to ordinary trunk ports. After issuing the no port-channel and various switchport commands, i saw that there were no flashing lights on the switch (i was using a couple of 3750s). I tried everything i could think of to reactivate them - no shutdown, switchport mode access, switchport mode trunk, etc. In the end i just reloaded the switches and they came up fine. My question is, Is there any way to bring back up the ports after deactivating a Port-channel without reloading the switch?

Thanks in advance.


Re: Re-activating ports after Port-channel deactivation.

Hi There

Do you know if your ports went into "err-disabled" state?

You can check whether the Ether Channel ports are in "err-disabled" state by using one of the following commands,

1. "show interface fx/xx" (for each of the ports which were configured in the Ether Channel). Look for the words "err-disabled" on the first line after the "line protocol" status.

2. "show interfaces status" This will show the status of all the interfaces on your switch and this should show if the ports are in "err-disabled" state also

If the ports are in "err-disabled" state, then running "shutdown" on the ports, follwed by "no shutdown" should have brought them back on line, without you having to reload the switch. Note that just typing "no shutdown" will not bring the ports out of "err-disabled" state.

If the ports just stopped working, then you may have to reload the switch.


Best Regards,


Hall of Fame Super Blue

Re: Re-activating ports after Port-channel deactivation.

In addition to Michael's post, if you disable the etherchannel you now have multiple connections between the 2 switches and Spanning Tree will have to calculate a loop free path.

I suspect this is why you ports went into err-disabled mode.


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