An anonymous reader writes "An often overlooked fact about network bandwidth utilization is that the bandwidth consumed on networks is more than the sum of the data exchanged at the highest level; it's data+overhead+upkeep. In the early 90's I worked for a large multi-national company whose software engineering department had a transatlantic x.25 circuit connection to it's European engineering headquarters. It was necessary that the connection be 'on' 24x7 due to the spanning of a large number of time zones, disparate working hours and tight contractual requirements. Very large data transfers were sometimes operationally essential. But the financial people used to scream constantly about the circuit costs (charged per packet, IIRC) of several thousand dollars/month. The sys admin realized that if he just reduced the frequency of keep-alives, he could shave something like 10% off the monthly bill. This article points out that p2p applications are greater bandwidth hogs than one might think because of the foregoing and more - they also search, accept pushed advertising and do other transactions that are transparent to most users, but add up. I doubt that developers of those free p2p applications have gave much thought to efficiency. This will be no surprise to many of you, but helps explain why ISP's rushing to put caps on transfers."