How ISPs learned to stop worrying and love P2P

One month after Comcast aggressively defended its targeted use of TCP reset packets to delay or stop BitTorrent uploads at an FCC hearing last month, the company has reversed course and says it will stop targeting individual peer-to-peer (P2P)protocols when managing network traffic.

Comcast’s reversal came as a welcome development for BitTorrent, which had argued against the ISP’s techniques at last month’s FCC hearing on broadband network management practices. Ashwin Navin, BitTorrent’s president and co-founder, says his company has been negotiating with Comcast for more than two years on traffic-management issues, and that the recent media attention to Comcast’s traffic-management practices has served as “a catalyst” to announce the two companies’ collaboration. In return for Comcast’s cooperation, he says that BitTorrent will work with other companies to develop more-efficient P2P technology that will place less of a burden on network architecture.

“We are particularly enthusiastic about Comcast’s commitment to make their network management protocol agnostic -- neutral to all applications -- as well as their efforts to upgrade broadband speeds for both downstream and upstream traffic,” Navin says. “We will optimize our application to take advantage of their network upgrades and share those techniques with the broader Internet community.”

Marty Lafferty, president of the Distributed Computing Industry Association, says this newly announced collaboration between Comcast and BitTorrent was inevitable given the ever-increasing consumer and business demand for bandwidth and the potential of P2P protocols to deliver large files rapidly over the Web.

“I think we’re at the point right now where the advantages of P2P technology are so enormous that it has to go forward,” says Lafferty, whose organization sponsors the P4P working group that is working with ISPs and P2P companies to optimize P2P content delivery. “P2P is not an individual technology, but rather a set of practices that will enable ISPs to ensure the most-efficient possible delivery of payloads for their customers.”

Typically, P2P technology such as BitTorrent distributes large data files by breaking them up into small pieces and sending them through multiple sources. After all the data is received, the file is reassembled as a whole. While this method of file sharing is much faster and more efficient than relying upon one centralized server, it can cause traffic-management problems for ISPs because P2P protocols are mainly designed to download large chunks of data from sources wherever they can be found, and without particular regard to network efficiency.

This has led some ISPs to use controversial methods to either slow or stop P2P traffic on their networks. Last year, for instance, the Associated Press reported that Comcast has been employing technology that is activated when a user attempts to share a complete file with another user through peer-to-peer technology such as BitTorrent and Gnutella. As the user is uploading the file, Comcast sends a message through TCP RST packets to both the uploader and the downloader telling them that there has been an error within the network and that a new connection must be established. Because the message sent to users does not appear to be sent directly from Comcast, many critics have accused Comcast of sending forged or spoofed packets that they say are deceiving to consumers.