I am setting up a VPN between a remote office and my corporate LAN. I will be initiating a VPN between the two site firewalls. There is a Cisco 1821 series router at each site as well. The remote site's subnet is 192.168.3.0/24 and the main office is on 192.168.0.0/24. The internal IP address of the firewall at the remote office is 192.168.3.1/24 and the internal ip on the router at the remote site is 192.168.3.230 (this will be the Default Gateway on the network). This router has two Fast Ethernet's on it. I will need to add a route to the firewall for 0.0.0.0 0.0.0.0 192.168.3.1 for nodes to get to the internet.
What IP address do I need to assign the other interface (e1) on the router? Also, how do I configure the route get to the main offices network (192.168.0.0/24)? Also, explain wiring if possible.