Eric> NAT is what has prevented us from returning to the pre-1978 situation.
Keith> this is true only if you believe that [blah blah blah] The situation today with NAT is that hosts in separate realms can only communicate in 99% of the desired applications, though perhaps this falls to 80% if one stubbornly ignores the existence of tunneling and port redirection. Pre-1978, you were either directly attached to the Arpanet or you were pretty much out of luck. You have to be very much in the grip of a theory to regard these situations as comparable. Granted, it's easier to talk about the evils of NAT than to explain how billions of new routable addresses are going to be added to the existing routing system.
