Comcast's defense of P2P traffic management practices meets skepticism

Admits to using TCP reset packets to "delay" P2P file uploads

Critics of the US ISP Comcast aren't backing down after the company defended its traffic management practices in a Federal Communications Commission (FCC) filing last week by asserting that its tactics fall well within the bounds of reasonable network management practices.

Comcast has been under fire from advocacy groups such as the Electronic Frontier Foundation and the Free Press since last October when the Associated Press reported that the company was actively interfering with some of its customers' ability to share files online.

Essentially, the AP has reported, 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 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.

In Comcast's filing with the FCC, which came a little more than a month after FCC Chairman Kevin Martin announced that the FCC would investigate complaints about Comcast's P2P traffic-blocking, the company came out swinging against its critics by accusing them of using "extremist rhetoric" and "inflammatory hyperbole" in their accusations. Comcast says that it only interferes with P2P traffic when such traffic is at a high enough level to "degrade the activities" for all of its high-speed Internet customers.

Comcast acknowledges in its filing that it sends out TCP reset packets to delay or stop P2P uploads. The company vehemently denies, however, that these TCP RST packets are "forged" and insists that they are only used "to signal that there is an error condition" on the network.

"This action is nothing more than the system saying that it cannot, at that moment, process additional high-resource demands without becoming overwhelmed," writes Comcast, which compares its methods with those of "a traffic ramp control light [that] regulates the entry of additional vehicles onto a freeway during rush hour."

Comcast's critics, however, take issue with how the company characterizes its methods. For instance, when the EFF first tested Comcast's network for TCP RST packet use, it noted that such that such packets were not present in similar tests it conducted on connections provided by AT&T, Sonic or overseas ISPs. As the EFF noted at the time, several other ISPs have to deal with users that hog bandwidth on their networks, and many of them use tactics such as dynamic per-user traffic shaping that mitigate individual user's impact on their network by setting limits on how much data-per-second any user can transmit.

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Brad Reed

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