This next example shows a more advanced configuration.
Using a hub or switch, the end user can have simultaneous WAN-LAN connections.
The WAN connections will each have a true WAN IP and will again be straight on the DMZ. It's highly recommended that each be running a firewall to prevent intrusion.
The LAN connection will again use a DSL router and will share it's single connection to other LAN machines using NAT.
This example will save the problems of having to setup pinhole or port/IP mapping but again, THE WAN MACHINES ARE DIRECTLY ON THE INTERNET, so use caution and a good firewall!
Hope all this helps.
Ken