[c-nsp] UDLD enabling port prematurely?

[Peter Rathlev]

On Thu, 2014-07-17 at 15:14 +0700, Victor Sudakov wrote:
> [...] I need some sort of point-to-point L2 link fault management
> between the switches.
>  
> Is UDLD suitable for this purpose? I have experimented a bit with
> "udld port aggressive" and have found out the following strange
> thing.
> 
> When the physical link goes down, UDLD detects this condition and
> shuts the switch interface down. However, after several minutes, the
> interface goes up again with "%PM-4-ERR_RECOVER: Attempting to recover
> from udld err-disable state on Gi0/17". The interface is up even
> though "Current bidirectional state: Unknown", and seems to be in the
> STP forwarding state.

This is because UDLD errdisable recovery has been enabled. You can
disable it with:

   no errdisable recovery cause udld

Problem is that you have to intervene manually to enable the interface
after service has been restored. But at least you will not have loops.

I'm not aware of a more elegant solution to your problem, but I'm
interested in hearing about one.

-- 
Peter