I got a router with two nics - 'a' and 'b'.
I have to setup a static nat for traffic coming from 'b' ip space to 'a'. The router has two equal cost default gateways - one on 'a', and one on 'b'. The trouble I am having is the reverse path for that nat is taking a different route from where it came from.
Does routing happen before nat'ing? How can I make the router to preserve the flow state, i.e. route back the natted traffic through the same interface it came from?