Study: Cable System Is Interfering with BitTorrent Downloads

Published August 1, 2008

A new study reports Cox Communications may be routinely interfering with customers’ attempted file transfers through BitTorrent applications.

The study, by the Glasnost project of the Max Plank Institute for Software Systems, reported Comcast interfered with more than 50 percent of customers’ attempted BitTorrent transfers within a small sample group.

The researchers supplied 8,175 Internet users around the world with a Java applet that detects BitTorrent transfer blockage. Of 151 Cox Communications subscribers involved in the study, 82 experienced interference. The researchers report 573 of the total of 599 American users who experienced blocking were using connections facilitated by Cox Communications.

Many Connections Blocked

Comcast has been accused of similar network blocking during the past year, having blocked 491 of 788 participants in the Glasnost project study.

Glasnost project leaders were careful not to single out Comcast and Cox Communications in their findings. The initial report states, however, “while we did observe blocking for hosts in 10 other ISPs [Internet service providers], we did not see widespread blocking of BitTorrent traffic for hosts in those ISPs.”

The Glasnost report did not take into account throttling, or download size limitations, in its findings. The institute states, “The results we present here are limited to hosts whose BitTorrent transfers to our servers are blocked, i.e. interrupted by RST packets generated by an ISP.”

Customers Informed

Cox Communications has included provisions in user agreements to give it flexibility in network management. The contracts inform subscribers that protocol filtering and traffic prioritization may slow performance at certain times of day. This part of the Cox customer contract allows greater latitude in throttling and interfering with harmful or illegal downloads.

Prof. Chris Cotropia of the University of Richmond Law School argues the federal “safe harbors,” which protect providers from liability to their users, and copyright infringement questions are not applicable to Cox Communications.

“Right now, telecommunications providers and ISPs enjoy certain safe harbors that shield them from copyright infringement liability,” Cotropia noted. But, he added, “The safe harbors incentivize companies like Cox to play no role regarding Internet file sharing.”

Debate Over Rules

A major issue among organizations pressing for net neutrality laws is the transparency of network management policies by ISPs such as Cox Communications and Comcast. The Glasnost project’s finding that interference takes place around the clock runs against ISPs’ claims that network management happens only during periods of high congestion.

Robert Atkinson, Ph.D., president of the Information Tech and Innovation Foundation, believes Comcast and other ISPs are following Federal Communications Commission (FCC) rules.

“As long as ISPs’ network management policies are transparent, fair, and their express purpose is to address the impact of certain data-intensive traffic on the network, they are in accordance with the FCC’s Internet access principles,” Atkinson said.

Atkinson added, “The notion that broadband networks are in some way fundamentally different than other networks and should deal with capacity limitations through network expansion is not supported by logic or long evidence from other network infrastructures.”

Peter Eckersley of the Electronic Frontier Foundation disagrees. Eckersley said, “It is essential that ISPs do their network management in a transparent fashion, and they should go to the greatest lengths possible to do so in a standards-compliant and nondiscriminatory manner.”

Eckersley added, “In the case of peer-to-peer, Comcast and Cox chose a discriminatory and non-standard means of traffic management. … Instead of just slowing those connections, they actually interfered with them.”

Calls for Transparency

Experts are divided over how the institute’s findings will influence the net neutrality debate.

Cotropia believes there are two paths available to ISPs and users in the near future. “If their [ISPs’] actions of throttling big file transfers are seen as targeting certain types of net activity, they certainly seem anti-net neutrality,” he said. “If Cox’s actions are seen as content-neutral and just a limitation on the bandwidth of one’s account, then their actions do not necessarily run contrary to net neutrality.”

Atkinson wants the industry to become more transparent in its bandwidth management. “One consequence I hope comes about from this is better self-regulatory efforts by the industry as a whole, working with other players to make policies and practices clear. … To some extent this is already happening with the Comcast agreement with BitTorrent.”

Eckersley expressed interest in FCC oversight to enforce transparency in network management. He said, “The fall-out from [an FCC complaint by advocacy groups] has included an admission by Comcast in particular that they could manage congestion on their network in a nondiscriminatory fashion.”

Eckersley expressed hope the report “will also result in clear leadership from the FCC that ISPs must be transparent in their network management practices.”

Nicholas Katers ([email protected]) writes from Franklin, Wisconsin.

For more information …

Glasnost study results: