Meraki WAN Failover

[Riser]

We have Building A with its own ISP and an MX100, Building B with its own ISP and an MX67. Both buildings / MX hardware being on separate networks in the Meraki Cloud. The goal is WAN failover using each buildings ISP hookup on the MX devices. Unfortunately setting up a warm spare as I’m sure you know is not possible due to mismatching MX hardware between the two buildings.

We’re utilizing Ubiquiti NanoBeam 5AC’s to get a WiFi bridge between each building into Cisco Catalyst switches in both buildings that are connected to their respective MX devices.

We are looking for some possible solutions as we’re unsure of what the most logical implementation would be in this scenario whether that be VLANs or possibly utilizing the L3 Catalysts to create some type of manual failover logic between the two ISP hookups. I know ideally getting matching MX devices and utilizing Meraki’s HA / warm spare is the direct solution. But hoping to see if there’s any viable solutions with our current setup.

[KH]

Hey @Riser 

Is there any reason we can't use the switches and have a pruned VLAN(s) for the ISPs between both buildings to provide WAN 2 to both MXes from both ISPs? 

[PhilipDAth]

The complexity of this solution is huge because of the limitations being placed on the solution.

My advice - don't do it.

[GIdenJoe]

If you have the IP address space or are using private IP's on the WAN you could ferry both ISP's over to the other building using 2 "external" VLANs.  So you could get WAN circuit redundancy for both buildings.

However your MX'es will remain single unless you get a secondary device of each type which doesn't cost that much and does not require a separate license.

Trying to mix both networks to both MX'es is only technically possible if you use a Cisco native Catalyst mode switch and VRF's and use some fancy floating static routes.  However in that case you would never be able to announce these networks to each other over SD-WAN since that would require NAT.  So as already been said, your solution would reach quite a complexity without much added benefit.