At our core, we have a primary fw (2951) and a backup fw (2951). Each has it's own dedicated connection (seperate ISP's).
Right now, all branch offices connect via isakmp to the primary fw. I would like to setup each outside site to automatically switch to the backup fw in the event that the primary fw or connection goes down.
Looking for some guidance in setting up priorities and how default routes are handled.
There's way too few information in your post to give you some solid answer.
I would start by checking the availability section in command reference:
Depending on technology you're using, but "preferred peer" is what you might be looking for.
First of all what we'd need to understand what is already configured on the 2951s and on the other ends.
Second of all (and depending what you have configured now) you may choose to have redundancy/availability on IKE level or on RP level (or both ;-)).
Some info about topology apart from the 2951s would be also interesting (especially in term of how you route traffic to the 2951s)
Third, do you require fallback to primary 2951 when it's available?
Any extra features to be applied? (QoS, load-sharing, WCCP?)