Hi, I am reading the CCNP CERT book and want to clarify how MST chooses whcih link to use when connecting to a PVST switch.
The book seems to state that all trees converge on MSTI-0, but this seems incorrect to me.
I would have thought that MST would need to interact with PVST to allocate the VLAN into the correct tree MST-instance?
Yes MST is backwards compatible. I found a good source explaining how an MST region interacts with non-MST switches. MSTI-0 is correct. The white paper below explains how MST accounts for non-MST switches when multiple VLANs are involved. Towards the bottom are a couple links explaning the migration process with configuration and debugging output.
Thanks Aaron, good link.
So at the MST boundary the MST topology converges on a common point, and uses the IST to communucate with PVST on an adjacent switch, so only one entry / exit point forms between the MST region and PVST switch regardless of how you configure cost per VLAN/Instance for each port.
I am looking forward to getting my hands on some switches to try this stuff out.