We have bought two Pfsense SG-4860 boxes. We have our equipment in a colocation datacenter. Our goals for this project is to have a redundant network with both routers connected to a WAN. The Colocation WAN offers us two equal costs redundant uplinks. When two WAN cables are connected, the colocation WAN uplinks are going to load balance over the two WAN uplinks. So when a package from R1 is send over Uplink1, the reply may come back at uplink2 - R2.

I'm looking for a solution to stack both boxes together so they maintain the same state tables. I already tried to setup a CARP but that is not working over load balancing WAN uplinks.

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  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer.
    – Ron Maupin
    Commented Feb 21, 2018 at 18:27

1 Answer 1


I don't think you are going to find such a solution. Routing is decided on a hop-by-hop basis, and each router is independent of other routers, each maintaining its own tables.

One way to get around the problem is to use loopbacks with public addresses, and NAT on the loopback addresses. Then any traffic coming back to the loopback of Router 1 through Router 2 will be properly sent by Router 2 to Router 1 for translation.

Unfortunately, this requires you to use more public addresses, which are in short supply for IPv4.

  • How is traffic exacly routed to my second router? Can you maybe add some instrutions how this is exacly setup? Commented Dec 12, 2017 at 15:00
  • You will need to give us the network device models and configurations. What routing protocol are you using internally? That is how you route networks from one to the other.
    – Ron Maupin
    Commented Dec 12, 2017 at 15:03
  • Pfsense SG-4860, it's currently a simple one router WAN / LAN configuration with NAT. We don't use the second router for now Commented Dec 12, 2017 at 15:48

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