RSTP Root Switch Confusion

[Einstein]

We run a stack of 7 switches (all Meraki MS210), along with 2 IDF's (Cisco SG 500's) in our building. Meraki switch #1 is physically set up as to be root. I am confused as to the wording under "RSTP ROOT" under switch #1. It lists a MAC address (which is one of our IDFs?), priority 32768 via Meraki switch 4 port 48 and local port 48. Under Switch, Switch settings I can choose a stack, but not a single switch to set as root. A little guidance would help me out. I have combed the forum here, and have found many articles regarding enabling RSTP, which I do have enabled. The descriptions are just fuzzy to me. I have been battling some minor latency issues, I was just crossing things off my troubleshooting list when I came to this.

Thank you all in advance.

[BrechtSchamp]

It means that switch #1 is not actually root.

Here's a few examples:

1. 
   
   This means that the switch you're looking at is not root. The root switch is CAMPUS-SFO-IDF1.1.4-MS220-24P and this switch is connected to it via port 3 (note that this is port 3 on the switch you're looking at, not on CAMPUS-SFO-IDF1.1.4-MS220-24P).
2. 
   
   That means that this switch is not root. The root switch is CAMPUS-SFO-IDF1.1.4-MS220-24P (still the same of course). This time the switch you're looking at is not directly connected to the root switch. It is connected to the root via another switch in the stack, namely CAMPUS-SFO-IDF1.1.1-MS350-24.
3. 
   
   This is what it looks like if the switch you're looking at is root.

How did you set it up so that switch 1 is root?

[ww]

in addition to @BrechtSchamp . A stack of switches functions as 1 switch. so its correct that you can only select the switch stack as root and not just switch 1.

[Einstein]

So is RSTP not a concern, or having a root switch not a concern when configured as a stack? Now I have other questions...

[Nash]

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@Einstein wrote:

So is RSTP not a concern, or having a root switch not a concern when configured as a stack? Now I have other questions...

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RSTP will treat your stack as a single switch.

Assuming your switch stack should be root:

If you have other switches in your environment, beyond your switch stack, then I would setup an identified root switch. 

If you might ever have other switches in your environment, I would setup an identified root switch.

[BrechtSchamp]

Within the stack it doesn't really matter which switch becomes root. If you only have the stack my recommendation would still be to manipulate the root bridge priority value so that it'll be root in any case (i.e. lowering the value, lower means more priority in the root bridge election). That way if you end up connecting another smaller switch with a lower MAC address to the network you won't end up with a root-change and a reconvergence. The root-switch is usually a switch that is central to your network.

[Einstein]

So since my current setting show one of my IDF's as root, should I just set my current stack to 8192. That way my main switch stack would always be root, but don't worry about individual switches in the stack. Sorry that sounds confusing....

[Nash · Accepted solution]

If the current stack should be the core of your network, yes. Lower its priority value so that it will be designated as root.

I highly recommend doing this during a maintenance window! Spanning tree will recalculate when you make this change, and this can cause network interruptions.

[Einstein]

Just because we have our VM farm plugged into it. Just figured we would make it root switch. But know seeing as it is a stack, I wonder how important having a root switch is. I also tried to make sure it was the switch booted first. We recently went through a massive power outage which blew out one of our large APC units. I booted switch #1 first again, but troubleshooting this latency is when I noticed the RSTP error.