Months after third parties were able to demonstrate that Comcast was throttling some BitTorrent (and Lotus Notes, since fixed) traffic, the cable giant has quietly changed its terms of service. Comcast updated the ToS on January 25—the first update in two years, according to company spokesperson Charlie Douglas—to more explicitly spell out its policies on traffic management.

According to Section III of the revised ToS, Comcast "uses reasonable network management practices that are consistent with industry standards." The company points out that it is not alone in the practice, saying that "all major" ISPs engage in some form of traffic shaping. Comcast does it to keep its subscribers from suffering the heartaches of "spam, viruses, security attacks, network congestion, and other risks and degradations of service" and to "deliver the best possible Internet experience to all of its customers."

The revised language exactly mirrors that of the FCC's 2005 Internet Policy Statement, which allows ISPs to engage in "reasonable network management." At the same time, subscribers are entitled to run lawful applications and services, access their choice of lawful content, and hook up any hardware as long as it doesn't harm the network.

Not long after Comcast's traffic management practices came to light, the company was hit with a class-action lawsuit by a disgruntled subscriber. Online video provider Vuze complained to the FCC, and the Commission officially opened its investigation of the cable company in mid-January.

Since the investigation began, the FCC has been bombarded with comments from angry users. "If you so much as open a BitTorrent client on a computer on the Comcast network, your entire connection drops to almost a crawl," says one comment. Another user: "I have experienced this throttling of bandwidth in sharing open-source software, e.g. Knoppix and Open Office. Also I see considerable differences in speed ftp sessions vs. html. They are obviously limiting speed in ftp as well."

Comcast has denied throttling BitTorrent traffic, saying that the ISP just "delays" or "postpones" it on occasion. One analogy used by a Comcast executive was that of trying to make a phone call and getting a busy signal for a time, until the call actually goes through. A more accurate explanation of Comcast's use of TCP reset packets, to build on the phone analogy, would be talking on the phone with someone and then both of you hearing the other's voice saying "hang up." That's the effect of the forged reset packets: convincing the BitTorrent clients that the other(s) have stopped responding.

Douglas told Ars that the change in the ToS was made to better clarify the company's policies. "We updated the terms of service as part of our normal course of business," he said.

Comcast's decision to affirm its traffic management practices in the newly revised ToS is a welcome baby step towards greater transparency. Subscribers (disclosure: Comcast is my ISP) would love to see even more transparency from the company, which remains cagey when it comes to its nebulous usage caps as well as what type of traffic is liable to be "delayed."

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