I am trying to accomplish the same things as a number of others on the forums here but I do not wish to use NAT as this will be an internal router on private Metro-Ethernet connections. I have prepared and attached a diagram displaying what I would like to do. Basically, I need my default router to be router A unless there is a failure. Right now everything is static. I'm all for doing dynamic routing if that is required. Please let me know if you need any additional information. The biggest difference between my setup and other is no NAT.
You can use statics for this setup. Is this your default route out to the internet as well? If so, you can do:
ip route 0.0.0.0 0.0.0.0 10.30.31.254
ip route 0.0.0.0 0.0.0.0 10.30.30.254 250
If you're just needing to get to that network, you can use:
ip route 10.20.20.0 255.255.255.0 10.30.31.254
ip route 10.20.20.0 255.255.255.0 10.30.30.254 250
I'm looking at the perspective of Router C. Your other routers will handle it from there.