Comcast Blocking Some Subscribers' File-Sharing Traffic

Comcast, the nation's largest cable TV provider and operator of a broadband access service with 12.4 million subscribers, or 20% of the U.S. market, is blocking the file-sharing traffic of some of its subscribers in an effort to manage the large amounts of bandwidth they are using. After seeing reports of such blocking on DSLreports.com and other forums, the AP tested Comcast's network and found the company is intervening between those uploading and downloading files on the BitTorrent file-sharing network, and terminating some of those connections. While many ISPs engage in "traffic shaping," or giving less preference to bandwidth-hogging applications like file-sharing, the AP called Comcast's blocking "the most drastic example yet of data discrimination by a U.S. Internet service provider." Tests were also run on connections offered by Time Warner Cable, Cablevision and AT&T, and the AP found no similar evidence of blocking.
http://dmwmedia.com/news/2007/10/19/ap-comcast-blocking-some-subscribers-file-sharing-traffic