I am not sure I am following the argument here. as far as I can make out 1. Many (all!) providers underprovision (aka oversell) their bandwidth, expecting peak utilisations to be approximately the provisioned amount because experience has shown that actual usage is only a percentage of theoretical purchased bandwidth 2. If "power users" use even half the bandwidth they were *sold*, then that has to be made up from low-bandwidth users to maintain an average in line with actual provisioning; the price charged is actually based on the provisioning, not actual usage or sold bandwidth, and is therefore profitable only if the actual usage matches statistically 3. most power users eat bandwidth from a single machine downloading at the maximum achievable rate and/or running servers; however, some could well do so using multiple machines using NAT, and some otherwise low-bandwidth users could possibly use more bandwidth if running multiple machines behind NAT (based on the idea that low bandwidth users can't possibly use a multi-user OS like linux and dumb terminals) 4. Trying to bandwidth limit users to a fraction of the bandwidth they were theoretically sold (and/or similar schemes like total data transferred caps and excess data usage charges) are politically and techically awkward; customers don't like trying to understand that you sold them a product that you knew in advance you couldn't provide, and tend to look around for lawyers when that happens 5. therefore making the sale or advertisting of NAT devices illegal (and by extension, commercial firewalls such as checkpoint's fw-1 and nat-capable cisco routers) is only reasonable and perfectly defendable. it is the hop from 4 to 5 I am having trouble with....