Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
New Member

Supervisor Failure and UDLD


We have experienced the following issue a couple of times.

Access layer switch - 6506, dual Sup32 running high availability. Has uplinks to distribution switch A from ports 5/1 and 6/1 and to dist switch B from ports 5/2 and 6/2. Uplinks are routed and are LACP Etherchannels. We run EIGRP with NSF and we also run UDLD aggressive mode.

We have noticed when we have a supervisor failure and subsequent failover on the access switch that all distribution ports connected to the access switch gets disabled with a UDLD aggressive mode error. Even from the supervisor that is not failing? Thus we are left with an isolated access switch even though it is still operational.

Has anyone else seen this. Considering turning off aggressive mode to see if this stops this problem.

Any help would be appreciated.


Re: Supervisor Failure and UDLD

To display the errors reported from the diagnostic tests, the diagnostic level, and the action that the supervisor engine takes after a diagnostics test failure, use the show test command.


Re: Supervisor Failure and UDLD


I've had the same problem as you.

redundant sup fails, uplinks to the core become err-disble due to UDLD.

Only difference is that our links on the c6500 with the failed sup are not on any of the 2 sups, but on a 48 ports SFP module.

We were cut off untill UDLD recovered himself after I think 3 or 4 minutes. But nevertheless, this should not be happening.

Did you find already a solution?


New Member

Re: Supervisor Failure and UDLD

Hi Dario,

I have not found a solution to this as yet, I need to complete the testing without aggressive mode on to see if that makes a difference. Will let you know the outcome once I do.

Regards, Ian

CreatePlease to create content