Two MX + multiple MS stacks without aggregation switches


Two MX + multiple MS stacks without aggregation switches

Hello! Please, advice, if it is possible to implement two MX routers with VRRP by ethernet with the multiple MS switch stacks, connected directly to the MXs without any aggregation switches/core switch etc?

One MX router works fine, but two MX routers are going down in this case.

Screen Shot 2019-07-05 at 10.36.31.pngScreen Shot 2019-07-05 at 10.38.27.png

Thank you for any advice or help!

8 Replies 8
Kind of a big deal
Kind of a big deal

remove the direct link between the two mx


Hi, thanks for your reply! I`ll try to remove ethernet for vrrp, seems like a working suggestion!


So, it seems to be OK, but when I insert the last switch stack (fourth), my network is going down.

Four switch stacks are inserted in 19,20,21,22 master router ports

Three switch stacks are inserted in 19,20,21 spare router ports.

Forks fine until I insert fourth switch stack in the spare router.

Router ports are configured to Trunk, no native vlan, drop untagged traffic.

Switch ports are configured with the RSTP enabled and STP guard disabled.




Kind of a big deal

If three stacks works fine, and fourth causes an error then I'd double check whether the gear involved in the fourth stack is configured identically to the rest.


Are there any other links between the stacks?


No, There are no another links between any switches/stacks (except of stack cables on switch stacks).

All ethernet and sfp ports configured with rstp enabled and stp is checked as loop guard.

Strange thing is if I connect every stack per router (4 + 4 links total), network goes down. And if I disconnect physically one of the links (exactly ANY of the links, on any router) - it works fine.

I think, the trouble is in vrrp anyway (but direct vrrp ethernet link is disconnected, vrrp vlan is present and all the connection (mx-ms stacks) links are configured to allow all vlans, as trunks, dropping untagged traffic. vrrp vlan is configured with /30 subnet mask).


I am planning a similar design for my network with multiple stack with different subnet downstream, however all my distribution are L3 switch to do inter-vlan routing.  So I plan to use only a transit vlan between MS to MX for routing.  Would like to get feedback if below setup and connectivity will work , as I did not see any document with similar topology to validate. I have 3 distribution segment in different buildings as in below picture. 


Question1 : Should I use a single transit vlan between all the distribution switch stack to MX or can I have separate transit vlan between each distribution segment to MX?


Question2: For this 4-switch stack in main building, I use switch 1&3 uplink to MX1, switch 2&4 uplink to MX2 for HA. Is this connection valid? Because, Meraki document says each MS should connect to both MX, however they use only 2 switch in switch stack, they havent provide detail on what if the stack is of bigger size. 


Meraki MX to MS connection.jpg






Kind of a big deal

Check the recommended setup here, I think you need to add a few cables so that each switch that uplinks to the MX's, uplinks to both of them :


This topic may also be of help to you (mind you it's a long topic):


Also, direct link between the MX's is not recommended.

Hello, thank you for your reply. It`s the switch stacks, as I described above.

Get notified when there are additional replies to this discussion.
Welcome to the Meraki Community!
To start contributing, simply sign in with your Cisco account. If you don't yet have a Cisco account, you can sign up.