LEDBAT: The New BitTorrent Congestion Control Protocol

A few months ago, BitTorrent developers announced that the transfer of torrent data in the official client was about to switch to a new application-layer congestion-control protocol using UDP at the transport-layer. This announcement immediately raised an unmotivated buzz about a new, imminent congestion collapse of the whole Internet. As the new congestion control aims at offering a lower than best effort transport service, this reaction was not built on solid technical foundation. Nevertheless, a legitimate question remains: whether this new protocol is a necessary building block for future Internet applications, or whether it may result in an umpteenth addition to the already well populated world of Internet congestion control algorithms.