Redundant design with non-stackable MS120's and MX84's

[RH6379]

We have 12 MS120's in a remote office and a single MX84.  This was a new install last week and the MX84 stopped connecting to the Meraki Cloud.  We did t-shooting with Meraki Support and they determined it's a faulty MX84.  I'm going to suggest to the higher ups to purchase a 2nd MX84 to be used as a warm spare.  We have the following set up

Switches 1-6 in Rack 1

Switches 7-12 in Rack 2

MX84 in Rack 2

I want to do the following:

Uplink Switches 2-6 to both switch 1 and 7 with 1Gb connections

Uplink Switches 8-12 to both switch 1 and 7 with 1Gb connections

Connect Switch 1 to Switch 7 with 1Gb connection

Connect 2 MX84's to both Switch 1 and 7

Connect MX84's to each other for VRRP

Connect Comcast Router to both MX84's

Switch 7 will be the primary path out to the internet and Switch 1 will be the secondary path out.

Switch 7 root bridge value is 4096

Switch 1 root bridge value is 8192

Will I have to disable ports from MX84's to Switch 1 for this to work properly or will this work as shown below?

[Adam]

Just an idea but why not wire switches 1,2,7,8 to the MX84(s).  Then wire the cluster of switches 1-6 and 7-8 like this https://documentation.meraki.com/MS/Stacking/Switch_Stacks#Physical_Switch_Stack_Configuration_Steps so that any one of them could go down and all of the rest in the cluster can talk to each other and upstream.  Then the gateway could live on the MX?  

EDIT:  Otherwise I think your diagram will work fine as well just potentially a lot more cabling depending on the distance between racks.  Also most of those links between racks probably take the same path so are equally susceptible to a line cut.  

[RH6379]

I didn't think the MS120's support Physical or flexible stacking.  Was that what you were referring to when you said to cluster the switches?

[Adam]

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@RH6379 wrote:

I didn't think the MS120's support Physical or flexible stacking.  Was that what you were referring to when you said to cluster the switches?

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Sorry, probably just used the wrong terminology.  That is a physical wiring design for redundancy.  There should be no stacking configurations needed.  That wiring design would work on any switches with STP.  

[RH6379]

I'm sorry, but I'm still not finding what you're referring to.

Was it this?

[Adam]

Correct, obviously doesn't need to be those ports.  Could just as easily be 47/48 or whatever.  

[jdsilva]

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@RH6379 wrote:

Connect MX84's to each other for VRRP

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Don't do that. It causes a bunch of STP instability. And I have it from a reliable source that Meraki is going to remove this from their recommended topology 🙂

[RH6379]

So are they recommending to run VRRP via the switch port links?

[jdsilva]

VRRP hellos are sent out on every VLAN for which VRRP is running, on all available ports. Meraki does not supply any settings to control which port(s) these are sent on. So regardless of that "VRRP" cable, you are still sending via the switches. 

[RH6379]

OK. Thanks.