I'm currently trying to build a HA setup using Pfsense/CARP for the first time but i have a few questions about it.

On the LAN side i have 3 VLAN's and they failover fine using CARP, the problem is that i want WAN redundancy also. If the WAN link goes down, it won't failover and the primary instance becomes a sort of black hole. According to the Pfsense manual i need to set a VIP for the WAN interfaces but in my topology they are not in the same subnet.

How does this work if the public IP's are not on the same subnet, is this even possible?:

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1 Answer 1


You cannot do what you want on the WAN side with two different ISPs and two different networks. CARP is to fool LAN hosts, and the routers implementing this must be able to communicate on the same network for this to work on a network.

In your scenario, your routers would be the LAN hosts, and the ISP routers would be the routers. The two ISPs would need to cooperate and share a network, but that is not going to happen.

With routers, you need to set this up with routing. For example, you could have each router with a default route, but one of the default routes is preferred by metrics. When the primary default route fails, the secondary default route is automatically placed in the routing table.

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