Hello,
Very annoying behavior between a C3650 (IOS-XE 03.03.04SE) and a C2950T (121-22.EA14) . I have an MST spanning-tree with 2 instances (MST0 and 1). Same configuration in both but as soon as connect the C2950T on a simple trunk (copper wire CAT6), the state on the C3650 goes from forwarding to blocking (dispute) and I loose communication with the C2950T switch. It's doing that with my other C2950T switch also. I connect my switch to another C2960G switch and no problem at all. I've configured the ports to be "spanning-tree pre-standard" also.
There is no unidirectionnal issue, port goes auto 1000-FULL. I'm kind of lost right now and debug does'nt give anything.
Thanks in advance for your suggestions.
