2xASA + 2xWanRouter network project?

Question

Computer networks

Good afternoon friends!
Tell me the direction. What protocols and technologies to use on the network section.
There are two aces on the perimeter (let's say 5510) in Active/Standby mode. You need to connect to two WAN routers, it doesn’t matter what. Preferably balanced.

Answer 1

something like this, for example

, from each router, announce default in ospf with the same metric and there will be ECMP balancing on the output (if the ace knows how to do it). will not enter. active/passive