Unique ISP set up

[wheelz]

I just had a quick question.  My ISP gives me 3 DHCP addresses and I pay a little extra each month for a static IP.  The static IP they give me though is on a completely different subnet & gateway than the DHCP addresses I get from their DHCP server.  I would like to set up a redundant firewall but was hoping to not have to pay for more static IPs.  Is it possible in this situation to have the primary IPs of each firewall DHCP but then use my single static IP as the virtual IP even though they are on different subnets and use different gateways?  Sorry if that is a silly question but I have not run into this before.  Thanks!

[cmb]

Has to be static and all on the same subnet so that won't work for stateful failover. You can do CARP only on your internal interface, and just lose all your states when you fail over. That's what I do on one of my WANs at home where I can't get static IPs, have two DHCP IPs and just live with losing states when it fails over.