torriem at gmail.com
Wed Dec 3 10:58:11 MST 2008
Von Grant Fugal wrote:
> The goal here isn't to slurp up bandwidth, it's to get away from TCP
> because, frankly, TCP is ill suited to torrenting. In fact, wouldn't it
> be nice if they used something a little more like TCP Vegas, where
> congestion is detected based on RTT instead of waiting till packet loss.
> We can't get this better behaviour in TCP without a flag day, but if
> uTorrent adopts something like it, it will graciously step down and
> allow greater portions to the more greedy TCP.
Right. Bittorrent is very much not suited to TCP at all. You don't
need or want retry when a packet doesn't show up. you just get it from
another source. Furthermore, bittorrent doesn't care about *streams*
but rather *packets*. And it doesn't care what order they come in. I
am not at all sure whey the original protocol went with TCP to begin with.
The possibility of abusing UDP to bypass congestion and fair bandwidth
mechanisms has always been there, and in fact people were claiming the
sky was falling back when udp-based streaming media servers came online.
Of course bittorrent could be used to abuse bandwidth in this manner,
but frankly the use of tcp/ip in an abusive manner up to this point has
given bittorrent a real black eye in terms of acceptance by commercial
operations. So yes, if bittorrent can use UDP in a responsible manner,
it will likely cut back on the bandwidth that bittorrent currently uses,
by a fairly large amount.
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