Hi All,
i have a question about the automatic recovery after a failure that was detected by UDLD.
Background: we are running dual ethernet circuits provided by a carrier between two remote sites. Both circuits are configured as a
cross stack etherchannel on a 3750X stack at each site. The problem that we are facing is, that we had a couple of outages, where
there was a logical error of some kind in the carrier network. Both sites had a link on both circuits and the etherchannel was up, although
one of the circuits was not bi-directional anymore and was not passing traffic in one direction. This caused an outage because of loadbalancing
on the etherchannel some packets went down the uni-directional circuit and did not make it to the other site.
We are now thinking of using UDLD to detect such failures. The idea is to have UDLD aggressive disable the circuit when it becomes uni-directional, so
that it will be unbundled from the etherchannel and all packets will be using the remaining bi-directional circuit.
The problem that I have is the automatic recovery after the error-disable timer has expired and the problem is this:
Does UDLD check the circuit for being bi-directional prior to re-enabling it after the error-disable timer has expired ? If it doesn´t that would cause
an outage because packets would flow down the uni-directional circuit. Or even worse, if the circuit does not become bi-directional, it will stay
up although uni-directional, because UDLD will only disable the circuit when it goes from a bi-directional state to a uni-directional state and not
from a disabled state to a uni-directional state.
Thanks for reading. Any comments are appreciated.
Thanks
Markus
