Static Route using batch file

[eseabrook2008]

I'm trying to setup a batch file to add a static route for a VPN user. The problem is, the below only works if I put the exact interface ID in

route add 172.16.0.0 mask 255.255.0.0 172.16.xxx.xxx IF XXXXXXXX

If I don't specify the interface, I get an error (Interface index wrong or gateway not on same network as interface). Since I need to specify the IF (which changes every time I connect the VPN), how can I get that information for a batch file?

Background - access network data over VPN and access internet through local resources.

 

[eseabrook2008]

This is what I've done to set things up..

http://support.microsoft.com/kb/317025