See The Register for my follow-up on the BitTorrent meltdown story:
The internet’s TCP/IP protocol doesn’t work very well. As the internet’s traffic cop, it’s supposed to prevent applications from overloading the network, but it’s at a loss when it comes to managing P2P applications. This deficiency, generally known to network engineers but denied by net neutrality advocates, has been a central issue in the net neutrality debate. BitTorrent Inc has now weighed in on the side of the TCP/IP critics.
The next official release of the uTorrent client â€“ currently in alpha test â€“ replaces TCP with a custom-built transport protocol called uTP, layered over the same UDP protocol used by VoIP and gaming. According to BitTorrent marketing manager Simon Morris, the motivation for this switch (which I incorrectly characterized in The Register earlier this week as merely another attempt to escape traffic shaping) is to better detect and avoid network congestion.
Morris also told the media this week that TCP only reduces its sending rate in response to packet loss, a common but erroneous belief. Like uTP, Microsoftâ€™s Compound TCP begins to slow down when it detects latency increases. Even though TCP is capable of being just as polite as BitTorrent wants uTP to be, the fact that it hides its delay measurements from applications makes it troublesome for P2P clients with many paths to choose from. But itâ€™s sensible to explore alternatives to TCP, as weâ€™ve said on these pages many times, and weâ€™re glad BitTorrent finally agrees.
We strive to be fair and balanced. The nut is that we don’t actually know whether BitTorrent’s new protocol is going to work any better than TCP, as there’s no hard data available on it.