I have a successful implementation of IPSec encrypted GRE tunnels with EIGRP. I do split tunneling at all of the remote sites, sending only corporate/private traffic back over the tunnel interface and performing NAT on all public bound traffic to the 'outside' interface. I am now trying to add an additional connection to one of my locations as a backup to the Internet. What is the best way to do this?
I have thought about just creating a second tunnel on the router that uses the secondary public interface as the source and then modifying the routing metrics to have it be a less desirable route than the primary tunnel. I'm unsure how to handle the NAT translation though as I use the 'ip nat' command to overload the primary external interface and do not know if/how you can include a 2nd interface in this sort of configuration.
(for example, Serial0/0 is my primary/preferred internet facing interface and my NAT is setup to use the following command -- ip nat inside source route-map nonat interface Serial0/0 overload')
I would greatly appreciate any feedback/suggestions on this topic.
