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New Member

Troubleshooting an interface in a port-channel

Question……I’m trying to troubleshoot a downed interface that is part of a port-channel….my question is, should I remove the interface from the port-channel to troubleshoot it….currently when I’m troubleshooting the port in the port-channel the other interface goes down?  The devices are 3750 to a 3850?...also is there a good reference doc on this?

VIP Super Bronze

since the physical port is

since the physical port is already down, you can simply take it out of the portchannle, do your troubleshooting and when the interface is back up added it to the portchannel again. This way you isolate the port and don't have to worry about the portchannel interface.


New Member

That’s what I’m thinking also

That’s what I’m thinking also……Just curious should that be standard practice when troubleshooting an issue like this?

VIP Super Bronze

I don't think there is such

I don't think there is such standard, but it is probably a good practice.

Quick question, when having a

Quick question, when having a port-channel formed on 2 Gigabit interfaces and I remove one Gigabit interface from the port-channel, will STP immediately block it? I mean STP will always choose a port-channel over one interface although both provide the same BW?


kdsmith01 for your question I suggest you take good care of STP if you remove that interface, in case it will link-up to avoid any small outage cause by STP convergence.

New Member

thank u

thank u

New Member

Thank u

Thank u

Hall of Fame Super Gold

What kind of link is this?

What kind of link is this?  Is a copper port?  You can try running a TDR if the port is copper.  


  1. Command:  test cable tdr interface <BLAH>;
  2. Wait for 5 to 7 seconds; 
  3. Command:  sh cable tdr interface <BLAH>; and
  4. Post the output to #3.
New Member

>What kind of link is this? 

>What kind of link is this?  copper (Cat5e)
>Is a copper port?  sfp


Will try your suggestion..thanks

Hall of Fame Super Gold

Copper SFP doesn't support

Copper SFP doesn't support the TDR. 


You'll need to temporarily move the copper link to a dedicated copper port (GigabitEthernet port preferred) for testing.

New Member

Interesting…..ok thanks I

Interesting…..ok thanks I will note that.

Hall of Fame Super Gold

How to use Time-Domain

New Member

> Interesting Thanks for that

> Interesting Thanks for that link