Giving CARP a try
The pfsense router i built a year ago has been fantastic so I decided to kick it up a notch - I built a second one identical to the first to see if I can get CARP working. This is not an 'I absolutely need redundancy and zero downtime' situation - it is more of a 'I want to learn how this works and i think that not losing my Internet connection while updating a router would be pretty cool' scenario.
Having said that, I have a cable Internet connection and I know that my ISP will allow up to 5 dynamic addresses per customer. I have a managed switch on which I put 4 ports on a separate VLAN for the WAN side - one for the modem, one for each router, and an extra just for good measure. I see a post here that says that static ip addresses are required for carp (though the wiki says nothing about that) but there is a workaround. Could someone expand on that - maybe even on the wiki so others could easily access it?
I also have dyndns giving me a hostname so I can connect to my home network via openvpn when I'm out. I'm not sure how that would work - would dyndns point to the shared ip address and the 'active' node would respond?
So is CARP an option for me? Or do I not meet the requirements?
CARP/HA is incompatible with dynamic addressing.
Get a static /29 from them instead and you'll be all set.