CARP with multiple subnets

  • Is there a guide somewhere that explains how to set up CARP where one has multiple subnets running on the same WAN interface.

    When I attempt to create a new CARP VIP I get this message: "Sorry, we could not locate an interface with a matching subnet for xxx. Please add an IP alias in this subnet on this interface."

  • Rebel Alliance Developer Netgate

    The error message told you what needs to happen. Do what it says: Add an IP alias to each firewall inside the new subnet, then you can add CARP VIPs inside that subnet.

  • Thanks Jimp

    I've tried your suggestion and either I'm doing it wrong or the IPs haven't been set up correctly by the colo provider. They got the first subnet wrong so it's possible hey could have the 2nd one wrong too.

    As they are over an hour away, I'd like to ask exactly what settings you would use to potentially save me a trip.

    The "extra" subnet is tiny, I actually only get 3 workable IPs from it.

    The network address is: / 29
    The gateway is
    The colo provider reserves -
    That leaves me with three additional useable IPs -

    So am I to create a IP Alias with the following: / 29
    or / 29

    I tried the latter and then I tried a 1:1 NAT but it didn't work.
    If I try the former I get this error message "You cannot use the network address for this VIP"

    If I try setting up an IP Alias of / 29
    and then try setting up CARP for it the system tells me I have a duplicate

    Can I actually use those three IPs for anything useful at all?


  • I forgot to add: for those extra three IPs I don't have to have CARP. They will be used for non-essential operations. Does that make it easier?

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