I am setting up a new site, and our plan is to have a main internet connection with A GRE tunnel that the ISDN monitors to see if it needs to come up. We also need to make a VPN tunnel from behind this router over the main internet connection and then when it fails, over the ISDN internet connection. How would this be done? With 2 seperate tunnels, one to the main IP address and one to the ISDN IP address? I am not quite sure how this will work.