MULTI subnet on 1 WAN interface.

  • Hello, I found this documentation online on how to setup MULTI subnet on a LAN interface.

    I just want to make sure that this also works for the WAN interface? And should I follow it exactly for the WAN interface in terms of setting up those config and the firewall rules?

    I need this because I am setting up a failsafe but CARP wouldn't let me add CARP IP ALIAS that is not in the WAN subnet.


  • Rebel Alliance Developer Netgate

    Yes it works but if you're doing CARP you need:

    • IP alias in the subnet on WAN on the primary
    • a different IP alias in that subnet on the WAN on the secondary
    • Then add your CARP VIP for the new subnet

    Just like with the "real" interface IPs, you need three IPs in the new subnet at a minimum

    I suspect you were trying to put the alias on the CARP VIP which only works inside the same subnet.

    It's typically better to have your upstream link route the entire new subnet at your existing CARP VIP then you don't have to bother with any of that.