Implementing CARP failover in live setup

  • Hi

    I've been asked to implement a failover solution in a production environment that's currently running a single PfSense server as primary firewall.

    The firewall currently has about 20 public IP's configured as Proxy ARP virtual IP's. What do I do with these? Can i just change the type to a CARP address without any disruption of traffic flow?

    I'm asking because i want to make the implementation as painless and non-disruptive as possible.

  • First of all, do a config backup


    • Configure the second pfsense

    • Assign one of your public ips to this new pfsense

    • configure sync between both(configure sync on its own interface or vlan)

    • start to change ips to carp

    Try it not on production hours.

  • That's exactly what i was thinking i would do.  :)

    What's the difference between P-ARP and C-ARP adresses besides the ability to do failover?

  • Carp is designed for fail-over and sync between two boxes.

  • I'm just thinking for future scenarios…

    I have a couple of other customers with single-node pfsense firewalls. They too are using PARP adresses for natting ip's to webservers and such... Would it be adviseable to change their PARP adresses to CARP so their setup would be ready for a failover solution in the future?

  • Change to carp only when you have the second box to sync.

    To use carp, you need al least three ips on same network. One for each pfsense and others to balance.

  • Yes i need 3 ip's for each interface. But just to be sure that we understand each other… Here's an example:




    In my scenario fw00 has 4 extra IP's on the WAN interface.,,, These IP adresses would be entered as CARP adresses...I wouldn't need to configure anything additional on the fw01 for the failover to work, right?

  • That's right.

  • Perfect… Thank you so much for the sparring. :)

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