Multiple Spanning Tree and Priority

[tom.blackstone@broan.com]

We are in need of changing our CISCO 3850 environment from rapid-pvst to MST as we are replacing our Cisco 3850 Core Stack with a CISCO Meraki MS-355.  Meraki suggests we convert to MST.

I have a question on setting the priority for the instance. (FYI we have about 70 vlans, and I plan to create just one Instance and domain).

In rapid-pvst, you set the priority based of where the switch was in relationship to the Core.  example:

Switch C ---- connected to ----> Switch B ---- connected to ----> Switch A ---- connected to ---->Core Switch
Priority 12288                               Priority 8192                                 Priority 4096                               Priority 1

When you configure MST, do you set the priority of the instance in the same way?

Thanks for any help!

Tom Blackstone

[MHM Cisco World]

Yes it same, the Core must be the root of STP domain.
friend ask Meraki  about if root will be in your network or them

[paul driver]

Hello
You set in on the instance 
Example:
spanning-tree mst configuration
name STAN
revision 1
instance 0 vlan x,x-x 
spanning-tree mst 0 priority 0
spanning-tree mode mst

As for the migration, Please review this excellent post from CSC guru himself.

[tom.blackstone@broan.com]

Thanks for the information.  How would the priority be set on the switches connected to the CORE?

When I used RSTP, this is how I set the priorities on the switches attached to the CORE.  Is it the same with MST ?

Switch C ---- connected to ----> Switch B ---- connected to ----> Switch A ---- connected to ---->Core Switch
Priority 12288                               Priority 8192                                 Priority 4096                               Priority 1