Supercharged File Sharing

Cooperating with file-sharing networks could avert congestion.

As Internet service providers (ISP) struggle with increasing traffic from peer-to-peer file-sharing networks, some have resorted to simply throttling this data, attracting ire from both users and regulators. Under a scheme that should be rolled out early next year, some ISPs plan to take a different approach: cooperating with file-sharing networks so that they share data more effectively.

Credit: Technology Review

The new scheme is called Provider Portal for Applications (P4P), and it's a voluntary, open standard that requires ISPs to share some information about how their networks are laid out. Initial tests have shown that the P4P framework can dramatically speed up download times for file sharers while also reducing the bandwidth costs for ISPs.

Peer-to-peer file sharing has exploded over the past decade, driven by increasing consumer bandwidth and growing demand for large amounts of data. Rather than serve files from a centralized location, file-sharing networks scatter pieces of among thousands of individual computers and help users find and download this data. File sharing now accounts for about 70 percent of all network traffic, and some ISPs have found it hard to deal with the increased load. In August, Comcast was rebuked by the Federal Communications Commission for trying to throttle peer-to-peer traffic on its network.

The new protocol reduces file-trading traffic by having ISPs reveal some internal network information to peer-to-peer "trackers"--servers that are used to locate files for downloading. Trackers can then use this network information to arrange file sharing more efficiently, by connecting computers that are nearer and sharing files at the lowest resource cost to the ISPs involved. As an example, suppose someone running a BitTorrent client tries to download an MP3. As it stands, the file might come from a computer halfway around the world, even if someone next door also happens to have a copy. By using P4P, the tracker knows to connect computers that are closer together, requiring bits to travel less distance.

"We knew, as a peer-to-peer company, that in order for peer to peer to become successfully commercialized, network operators had to be cooperative," says Robert Levitan, CEO of Pando Networks, a company that offers commercial peer-to-peer content delivery services. "Instead of blocking traffic, they had to get involved in it."

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Pando is a founding member of the P4P Working Group, a consortium set up in 2007 to develop and test new technologies to make P2P more efficient. Members include the ISPs Verizon and Comcast, the peer-to-peer software business BitTorrent, the network equipment manufacturer Cisco Systems, and academic institutions including Yale and Washington University.

Small-scale tests conducted in March by Yale researchers, Pando, Verizon, and Telefonica Group suggest that the system could cut the average distance that data has to travel from 1,000 miles to 160 miles, and reduce the number of connections that have to be made through major hubs from 5.5 to 0.69. This would help ISPs avoid the costs incurred when information is handed between major networks. The approach could also benefit users, by increasing download speeds by an average of 20 percent, according to the same tests.