Issues with Bridge Priority

[SNSGS]

Hello, I'm having issues with getting a specific switch/stack as the RSTP ROOT in a network despite it having a lowest Bridge Priority. 

I've the core stack (comprises 2 x MS210-24P) with Bridge Priority 4096

I've the "master" switch of a stack (MS210-48P) with Bridge Priority 16384

The rest of the "member" switches (MS210-48P) with Bridge Priority 61440

Questions -

1. None of the uplink ports to the router or the ports involved to connect each stack have STP Guard enabled. Should I be enabling RSTP Guard?

2. Should the "master" & "member" switches in a stack have the same Bridge Priority or its OK to have as mentioned above.

3. How can I get the core switch/stack to become the RSTP ROOT?

I've read the articles on Meraki website but I'm still unable to get this working. Any help is appreciated. Thanks.

[KarstenI]

1) The Guards can have a benefit when implemented wisely. But on the infrastructure you should only set it when you know how your infrastructure behaves. On User-facing ports, using root- or BPDU-guard is probably a good idea.

2) It's ok that way. The preferred root has the best priority, your next preferred device if the first one fails gets the second best priority. All other switches can typically stay at the default or any value that is larger than the first two.

3) It already should be if there is no other STP-device in your network. The switches will tell you which one is the root. How did you test it that you say the core is not the root?

[SNSGS]

@KarstenI 

3) I clicked on the core switch and its listed in the Summary tab. The RSTP ROOT has the other switch listed with a higher bridge priority. I then clicked on that switch and noticed RSTP ROOT has the value "This switch".

[KarstenI]

Ok, that's strange. After double-checking the switch-priorities I would open a support-case and let them investigate.

[cmr]

@DarrenOC set our core stack to priority 0 on a site where we thought we had an STP issue.  It certainly worked 👍

[PhilipDAth]

The priority applies to the entire switch stack, not individual members of the stack.  Assuming this is a hardware stack.