The impact of Peer to Peer on ISPs
Submitted by brad on Tue, 2008-02-19 18:43I'm a director of BitTorrent Inc. (though not speaking for it) and so the recent debate about P2P applications and ISPs has been interesting to me. Comcast has tried to block off BitTorrent traffic by detecting it and severing certain P2P connections by forging TCP reset packets. Some want net neutrality legislation to stop such nasty activity, others want to embrace it. Brett Glass, who runs a wireless ISP, has become a vocal public opponent of P2P.
Some base their opposition on the fact that since BitTorrent is the best software for publishing large files, it does get used by copyright infringers a fair bit. But some just don't like the concept at all. Let's examine the issues.
A broadband connection consists of an upstream and downstream section. In the beginning, this was always symmetric, you had the same capacity up as down. Even today, big customers like universities and companies buy things like T-1 lines that give 1.5 megabits in each direction. ISPs almost always buy equal sized pipes to and from their peers.
With aDSL, the single phone wire is multiplexed so that you get much less upstream than downstream. A common circuit will give 1.5mbps down and say 256kb up -- a 6 to 1 ratio. Because cable systems weren't designed for 2 way data, they have it worse. They can give a lot down, but they share the upstream over a large block of customers under the existing DOCSIS system. They also will offer upstream on near the 6 to 1 ratio but unlike the DSL companies, there isn't a fixed line there.





