What the setup is:
On the machine their is eth0 (10.10.9.1) which is set up on the router to always go out ISP A (will say the IP is 188.8.131.52).
On the machine their is also eth1 (10.10.9.4) which is set up on the router to always go out ISP B (will say the IP is 184.108.40.206).
If ISP A goes down I want to somehow make the traffic go out ISP B while still keeping eth0 up for local connections (via the 10.0.0.0 network) and when both are up those connections coming into eth0 should always go out eth0 and those coming from eth1 should always go out eth1.
I was looking into fwmark and that may be my solution but need more details.