I've done research on the 'net and found other people that have done this, but I can't get it to work properly.
Please see attached config - I've got a LAN interface, 1 eth WAN interface & 1 DSL WAN interface.
I'm wanting to NAT out the eth WAN (FE0/1, ISP1) primarily, and out the DSL WAN (Dialer0, ISP2) in the event of a failure.
I've got the tracking, routing etc all working fine, so long as I do the NAT for int FE0/1 on an upstream box. If I mark it as 'nat outside' and put in the nat command (I've marked these on the config with <<<< and they're commented out) it won't fail over and the next time connectivity changes all traffic stops, and never starts again (until I take the nat commands back out for int FE0/1).
It also works vice versa, if I have the NAT commands in for int FE0/1, and removed for the Dialer0 it's fine (Traffic flows on the FE0/1 interface, of course it won't flow on the Dialer0 without NAT).
Really confused, any help would be much appreciated.