Site to Site VPNs IP Address



Hi all,
I have a test environment as follows -

IIS behind an ISA 2004 server , connected via an unmanaged (wires
only) ADSL from pipex (single static IP assigned by the provider). Im
using a a cisco 1701 combined adsl modem/router.

Is it possible with this setup to establish site to site vpn
connections to share the intranet, to users at offices running either
ISA 2K or Windows 2K3(RRAS).

If not whats the minimum number & types of IP Addresses I need to make
this scanario work ? & what interfaces should they be assigned to.

thanks in advance.
hals_left

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