For purely academic purposes, I'm trying to get an idea of how the 802.1D, 802.1Q, and Cisco spanning tree protocols have evolved over time.
I've been digging through web sites and looking at the 802.1 committee's pages.
The question I'm stuck on is when did the standard (.1q) allow for per-vlan spanning tree? I have read where 802.1s was integrated into 802.1q, which provided an MST capability in the standard...is that the same point when Per-Vlan Spanning Tree became available?
By Per-Vlan Spanning Tree, I'm referring specifically to the ability to define a different tree (or at least a different root bridge) for each VLAN. As I understand MST (based on Cisco MISTP), this is the ability to group multiple VLANs into the same tree, which is not what I'm after.
Can anyone help me out, or am I barking up the wrong tree, so to speak, with how the standard developed?
That's correct. There has never been any per vlan STP in the standard. Cisco solution only makes sense because it's more flexible to use than the IEEE standard. However, PVST has some limitation in term of scalability, and at a point, it's better to move to MST.