Support and News Forum

Hello,

When a blocked port on a switch becomes a root port in case of direct link failure, it sends a TCN to the root bridge. When the port goes into forwarding, it also sends a TCN.
However in Wireshark, the output says only one TCN is sent when the port goes into forwarding and that can't be.

Anyone knows about this behavior? I am using virl, I thought these were accurate?

Thank you,

When a switch with a blocked port becomes the new root port because its root port went down, normally the directly connected switch should send a TCN to the root bridge.
However the output of wireshark does not show any notification from that switch when it should, doesn't make sense.

Does anybody have an idea what the TCN doesn't show up in the output?

Thank you,

First advice to test such stuff is real switches, and CCNA learning course
Virtual switches have some restrictions to get what you described...
So real switch is your solution, and of course knowledge of CCNA