Actually that isn't quite correct. A router is needed to route packets both directions, in your case and in a no-NAT scenario. The ISP could make everything a f

Actually that isn't quite correct. A router is needed to route packets both directions, in your case and in a no-NAT scenario. The ISP could make everything a flat L2 network between consumers (you'd plug a switch into your ISP handoff), but that would be a bad idea on a lot of levels.