MST to RPVST+

[Rajagopal Sivaramakrishnan]

Hi All

We are integrating Cisco 6800 with Force 10 switches.. This is more of a migration process from the old F10 switches to Cisco, and we need to connect them together for this migration.

F10s run MST , with odd and even VLANs primary in each core switch. When we plug in 6800 with RPVST+, what is the consequence ? I have never worked with MST, and wanted to be 100 % sure before going ahead with the solution.  Basically, I want to move all the VLANs to have STP bridge as the Cisco switch and move it off the F10 switch.

Let me know if you need more info..

Raj

[Josh Sprang]

I would read the following:

http://blog.ine.com/2010/02/22/understanding-mstp/

From what I know about MST is instance 0 will be your CIST instance.   So if the 6800 is plugged in it will be considered instance 0 in the MST configuration of the F10. 

I would migrate the 6800 to MST or drop the F10 to 802.1W. 

In MST you need to have all the switches have the same mst revision, instance to VLAN mappings, and name or they will be in different regions and run spanning-tree over CIST between the regions. 

If you migrate the F10 to 802.1W one spanning tree instance should run over the untagged VLAN on your trunks. 

With MST I would be careful in adding VLANs during the day.  I have never ran it in production but during adding a VLAN in labs I have noticed a convergence will adding a VLAN since the instances don't match for a short period of time.

[Rajagopal Sivaramakrishnan]

Josh

Thanks for your inputs..  Ill read through this.. It looks more complicated the way it interoperates.. I doubt if I can convert the F10 switch to RSTP, since there are multiple other layer 2 switches on the network.

Raj

[Rajagopal Sivaramakrishnan]

I actually termed it wrong before.. What I was looking for is MST vs RPVST+ interop. I know F10 doesnt support PVST & RPVST+...  If MST was still running on Force 10 access switches, and I run Rapid PVST+ on the 6800 core, how will it interop ?

I see that the Force 10 might support the multicast MAC 0100.0CCC.CCCD ? Im going to do a test lab for this, but wanted your feedbacks on this topic...

Raj