BitTorrent, Inc., has produced a new version of the BitTorrent protocol called “uTP” which automatically throttles back BitTorrent connections when it detects congestion on the network.
For the end-user, the benefits are apparent – downloading (and uploading) a torrent should interfere less with other network activity – so one roommate can download while the other can watch NetFlix, or you could have uTorrent in the background while doing some other task, such as gaming or Web browsing, without huge stuttering.
The idea of putting network congestion control on Layer 7 also means that there’s less pressure on “Layer You” to introduce bandwidth throttling for BitTorrent traffic on the network or transport layers. This should come as a bit of a relief, although, even though two thirds of BitTorrent users either use uTorrent or Mainline, both of which have uTP, there’s still a third that doesn’t, so the guard can’t come down completely.
Where this might have a bigger impact, however, is at ISPs. For a while now, ISPs have been remarking that their networks are congested and that a large part of that congestion is due to P2P traffic. Indeed, a study by Ipoque in February 2008 showed, for example, that BitTorrent alone was responsible for 37% of Internet traffic. In Eastern Europe, that number was 56%. (No clue what the numbers are today; if anything, they may have gone down a little due to encroachment from streaming video services like YouTube, Hulu, and NetFlix.) Even so, assuming a reasonable 30% estimate for BitTorrent traffic on an ISP’s network, and two thirds of that now using the uTP protocol, you now have about 20% of your traffic that will throttle back down automatically in the case of congestion. That provides an awful lot of breathing room!
This is an especially important development considering that BitTorrent encryption is making headway due to events such as the forging of RST packet headers using Sandvine software, like Comcast attempted, and in response to ever more onerous copyright infringement laws, including “three strikes.” The large amount of BitTorrent traffic is also used as a justification toward introducing caps. Encrypted BitTorrent traffic can be harder to track, and therefore, harder to control on the network.
In fact, measures taken by ISPs in order to traffic shape BitTorrent traffic may have spurred the uTP protocol’s development. If the BitTorrent application developers view ISPs using traffic shaping protocols to defeat the purpose of BitTorrent – faster downloads using peer-to-peer connections – then encryption designed to make BitTorrent hard to throttle is the stick – while BitTorrent self-throttling is the carrot.
In many ways, uTP can be seen as more of an ideological development than a technological one. It’s been argued that BitTorrent throttling is less about network congestion and more about fighting copyright infringement of television shows – shows which are carried by the same cable companies that carry broadband. The “black market” competitor to cable TV, illegal downloads offer lower price (free vs. $50 or so a month), convenience (watch at any time), better quality (no commercials) and better selection (English-subtitled Dutch-language reality TV shows? Sign me up!) Eliminating the congestion problem at the application end then forces ISPs to either drop BitTorrent throttling – or forces them to admit that throttling isn’t primarily about congestion.
This is especially important considering that the Net Neutrality debate is heating up into a general political issue, and not a debate among techies; with Republican senators Hatch and DeMint writing an opinion piece in the Wall Street Journal against net neutrality legislation, and Mitchell Baker and John Lilly, chair and CEO of Mozilla, respectively, writing the counterpoint for net neutrality legislation.
At any rate, back on the microeconomic level, all I know is that now that I don’t have to worry so much about my roommate’s BitTorrent downloads causing lag in my gaming sessions. Time to kick some online butt.
