[c-nsp] UDLD misbehaviour

[Andrew Koch]

On Wed, Jul 13, 2011 at 16:15, Leonardo Gama Souza
<leonardo.souza at nec.com.br> wrote:
> Hello my friends,
>
> I had some problems on an optical fibre between two 6509 switches and
> UDLD
> kicked in to avoid STP loops, but when the switch tried to recover from
> the error-disable state,
> the link went up, even with optical fibre problems.
> This misbehaviour caused a major outage in the network. I couldn't find
> any known bug for the
> current IOS version 12.2(33)SXI3.
> I worked around the issue keeping the interface in a shutdown state
> until I
> resolved the cabling issue.
> Can someone shed some light on the solution?

It looks like UDLD did its job just fine.  The trouble is the
configuration of errdisable recovery.  By default, the switch will not
recover any errdisabled port.  This causes the port to stay disabled
until resolution of the underlying problem, allowing an engineer to
resolve before executing a manual bounce of the port.

"show errdisable recovery" will show your current settings.  The
defaults are all to be disabled and a timer of 300 seconds.

Andy