Hello,
I have two switches, linked together by a single port (sfp-sfpplus14 on each side). I’m trying to setup MSTP but something’s not working properly. I’ve set the bridge to use VLAN filtering, I’ve set the STP Protocol to MSTP and set the region name and revision number to match on both switches.
Now, since I’ve got multiple VLANs, some of which are only available on some ports (obviously), I wanted to have multiple MSTIs, and I’ve created them to match, on both switches.
The problem is that, while two MSTIs are “working” fine, as they elected the root bridge correctly and everything seems fine, the 3rd one, that’s set on a single VLAN seems to be having issues.
In the logs of the first switch, I see the interface (sfp-sfpplus14) flapping when it comes to MSTI 10, between LEARNING and DISCARDING. I don’t understand why that is. I have a single connection between the two switches that is transporting VLAN 2 (VLAN assigned to MSTI 10) so I don’t get why it keeps flapping.
Any help is appreciated!