Further to the news that Comcast is sneakily degrading BitTorrent transfers, Harold Feld offers this analysis of the idea that this somehow improves quality of service:
First, Comcast is not guaranteeing quality of service. Just the opposite. It is actively degrading service for subscribers, many of whom subscribe to high-bandwidth services precisely for the purpose of getting access to muckin' big files (or, frankly, they'd stick to much cheaper dial up). So when Comcast here speaks of "a responsibility to provide all of our customers with a good experience online," it really means "We are trying to screw up traffic of high-bandwidth users in a non-obvious way so we don't have to make expensive upgrades or engage in in obvious metered pricing." As I have written before, cable operators in particular face network capacity constraints because of the way they constructed their systems. So they are allowed to advertise their "always on, all you can eat" speed based on certain theoretical assumptions about network usage that are increasingly unrealistic.
Comcast's basic problem here is it wants it both ways. It wants to advertise all you can eat connections of the highest speed – because that sells so much better than alternatives like metered pricing or explicit bandwidth caps. But it doesn't want to deal with the consequences of the user behavior this sort of advertising generates. i.e., people using their Comcast connection all the time and expecting the advertised speed. Nor does Comcast want to deal with this the traditional way, by spending the money to build more capacity, then charging a higher price for the new "top speed." Comcast, like any other profit-maximizing firm, would prefer to avoid expenditures and, if it must spend money to gain revenue, would prefer to minimize expenses and maximize revenue. Inserting reset packets to degrade the reliability of BitTorrent, and therefore discourage its use overall, is much cheaper than upgrading from existing hybrid-fiber-coax to fiber. So, as I predicted over a year and a half ago Comcast makes the logical choice and degrades traffic that eats bandwidth rather than pay to upgrade.