One possible positive effect (for the consumer) of "per-bit" pricing is the opportunity to buy larger pipes but only pay for what you use.
The other possible effect is that you buy one of these, and then someone launches a DOS attack at you and you get the bill for it.
We have used usage-based pricing for collocated customers since SMARTNAP (now IXC Austin NAP) opened it's doors nearly two years ago. That allows us to hand people a 100Base-TX port and let them pay for the bandwidth they actually use. We don't bill per byte. Instead, we use the 95% sustained utilization model that bills for your peak utilization in Mbit/sec after throwing out 5% of the 5-minute samples for the month. The 5% amounts to about 36 hours of "free" bandwidth. That means you have to be a pretty serious smurf target before attacks will affect your bill significantly. Both we and our customers have been very happy with the 95% utilization model for this type of service. It lets us set pricing based on a metric that closely follows the amount of backbone bandwidth we have to provision to support a customer. UUNET uses the same metric for their usage-based T3 lines. I believe other providers also use it. Having said that, the 95% model isn't the end-all of usage billing. Some people want to use high bandwidth for a short period of time (e.g. a video conference) and just want to pay for that period of time. In the 95% model they either win big or they lose big depending on whether their high-bandwidth usage fits in the 5% window. There are still some customers concerned about the lack of control they have over their bill. Presumably, they will have a business model that provides them with additional revenue if their traffic increases. It still makes people nervous though. Using bandwidth-limiting mechanisms can alleviate that concern at the cost of reducing their available peak bandwidth.
The economic impact of this should not be underestimated. Per-bitrate pricing is a problem as long as the receiver pays for the receipt of transmissions they may not have solicited.
The 95% model makes a fairly primitive, but fairly effective attempt at addressing that issue. The issue will be more of a concern if finer-grained usage-based billing becomes more common. -dpm -- David P. Maynard, Flametree Corporation EMail: dpm@flametree.com, Tel: +1 512 670 4090, Fax: +1 512 251 8308 --