Hi
Had a nasty surprise yesterday. We have two 5406Rs connected to each other in VSF. Then we have a string of old Cisco switches daisy-chained to each other.
We connected it like this:

(sorry for the rotation, it looked okay on my pc before upload)
When I completed the ring, one of the 5406's rebooted and came back up with a split brain. We had a hell of a time bringing VSF back up to normal.
My guess is some looping occured even though spanning tree should have taken care of that. The VSF links are on a different line card. Uplinks to Cisco switches are 1 gig, VSF link is 10 gig.
Both Aruba and Cisco switches are running Rapid PVST. Arubas running software version 16.09.0009
Is this an unsupported configuration, or did I do something wrong?
Lars