Supercharged File Sharing

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A more recent study carried out this fall with Comcast, Verizon, and AT&T showed that peer-to-peer download speeds could increase 50 to 150 percent using the technology. And the amount of content that is delivered entirely within each ISP should increase from 14 percent to as much as 89 percent.

But the P4P approach is not without its challenges. The protocol depends on ISPs calculating and making available "p-distance values" to peer-to-peer trackers, to tell them how best to connect different file sharers. There are also legal questions. Because many files traded on peer-to-peer networks violate copyright, ISPs will want to make sure cooperating with P2P networks won't make them responsible.

Nonetheless, Richard Woundy, senior vice president for software and applications with Comcast, admits that the idea is appealing. "The ISP benefits because traffic isn't going over as much infrastructure," he says. "It's staying within a metro area, or at least staying within the ISP. It's not going over a transit link to an upstream provider."

Doug Pasko, principal member of the technical team at Verizon, says that Pando and Verizon have plans to roll out a P4P implementation soon, possibly by the end of January. The P4P working group has also submitted an application with the Internet Engineering Task Force to seek official approval for the P4P standard. And Pasko doesn't think that legal problems are likely. "P4P itself doesn't increase our legal exposure," he says. "That's because we're offering optimization guidance. We don't have any information on what that content is."

Comcast is also interested in implementing the technology, says Barry Tishgart, vice president for Internet services for the company. "Our inclination is, we want to do it. The results of our trial are very positive," he says. But the tests carried out so far have been relatively small: the one performed this fall shared a single 21-megabyte video file, which was downloaded 15,000 times. So Tishgart wants to see what happens when larger file sizes and large swarms of peers try to download a popular file.

Finally, the success of the scheme depends on the thousand or more peer-to-peer trackers that currently exist agreeing to use the P4P protocol. Tishgart says that they tend to be suspicious of the ISP's motives. But if they see performance gains for their users and no downside, then they may be much more likely to cooperate.