Hi @LuigiJuve, I'm not saying it won't work. What I'm saying is that it's not possible to configure a "heartbeat VLAN" as described in that document. It's a completely false pretense to think that this supposedly magical VLAN is any different from any other VLAN you have configured. As @NolanHerring pointed out, VRRP hellos (the "heartbeats") are sent out on every VLAN. Further, Meraki's implmentation of VRRP has elected to use a single Virtual Router with multiple Virtual IP addresses as opposed to a Virtual Router for each VLAN, meaning, that as long as a VRRP heartbeat makes is to the standby unit on ANY vlan the current active master will remain the master for all VLANs. It's not possible for only one VLAN to fail over. This is truly and Active/Standby only implementation. So please forgive me if this sounds harsh as it's not meant to, but your 15 installations are not working because you followed that guide, and they also are not working the way you think they are working. This is actually my objection to this configuration, and Aaron Willette's design. It's based on a falsity, and that falsity has been propagated to many corners of the Internet. Quite often people chime in here in the Community and reference that design, and nearly every time the person making the reference has no idea that it's simply not possible to actually designate a VLAN as a "Heartbeat VLAN". My preferred way to do Meraki Warm Spare, which has come from my own experience deploying Warm Spare for numerous customers, and through the very insightful advice of @PhilipDAth, is to NEVER EVER directly connect the two MX appliances together, and in stead singly connect each MX to a single switch or switch stack (the latter preferred for redundancy). See, having the MX's directly connected actually can cause issues under certain failures with Spanning Tree convergence. Further, it's also desirable to have the VRRP heartbeats traverse a path more representative of the path that user data actually takes. By creating a shortcut that heartbeats can take, but not user traffic, you are actually exposing yourself to a failure scenario where user traffic is blackholed, but VRRP is operation just fine and not allowing a failover to occur. Failovers are a good thing! You want failover to occur when there's a failure. A direct link cheats the system and can actually prevent a failover when you actually want one. I'll close this by pointing out that Meraki has actually changed their recommended topology for Warm Spare by removing the direct connection between MX's. It took me some time to convince them to do it, but they did come around 🙂 https://documentation.meraki.com/MX/Deployment_Guides/MX_Warm_Spare_-_High_Availability_Pair#Recommended_Topologies
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