I currently have a remote site. That site (Cisco 881) has an ipsec VTI connection back to my main office (Cisco 3845) passing thru an ASA5510. Everything on the tunnel between sites works great. But because we implement Internet filtering via the ASA5510, I want all traffic to be sent over the VTI tunnel, and out on the internet thru the ASA. 881 config is attached.
Remote Site 881 ---> ipsec VTI ---> 3845 ---> ASA ---> Internet
I believe that you will achieve your objective of having all traffic sent through the tunnel if you change your default route. Now it is:
ip route 0.0.0.0 0.0.0.0 192.168.15.1 which uses FastEthernet4.
Change it so that it uses Tunnel0
ip route 0.0.0.0 0.0.0.0 Tunnel0
or alternatively so that it uses the next hop address through the tunnel
ip route 0.0.0.0 0.0.0.0 10.10.10.1
When you make this change it should create a problem of recursive routing since the address of the tunnel endpoint will appear to be reachable through the tunnel itself. So before you make the change that I suggest I believe that you should first configure a static route for the tunnel endpoint. It might look something like:
ip route x.x.x.x 255.255.255.255 192.168.15.1
Give it a try and let us know how it works.