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Why BitTorrent Causes Latency and How To Fix It
Sivar recommends an article by George Ou examining why BitTorrent affects performance so much more than other types of file transfer and a recommendation on how to fix it. The suggestion is to modify P2P clients so that, at least on upload, they space their traffic evenly in time so that other applications have a chance to fit into the interstices. "[Any] VoIP [user] or online gamer who has a roommate or a family member who uses BitTorrent (or any P2P application) knows what a nightmare it is when BitTorrent is in use. The ping (round trip latency) goes through the roof and it stays there making VoIP packets drop out and game play impossible."
And we admit that on a small scale, we need to control our eating, but we don't want the grocery store telling us how much of things we can buy.
Read the bloody article. He shows that bittorent traffic capped to 10% of total bandwidth still causes more latency than an http download using 90% of the pipe. The total latency hit is small, but still significant for VOIP or high intensity gaming.
--why?
Well, since the article is about how to stop other users on the network from ruining your net experience, I think we assume they will be on a router of some sort.
You should have taken a quick look at the article first. The author basically experienced excessive lag even though he did cap his upload rate, compared to what an upload or download via a different protocol (FTP, HTTP, VoIP) would cause. This is because the BT client fires or receives packets whenever they are available, while the others receive or send packets in a spaced manner (unless they saturate the pipe). That means that even though your upload rate may be limited to 10 KB/s, if your total upload is 20 KB/s, you might experience a maximum lag of 0.5 seconds. The guy put up a lot of graphs to illustrate that it happens quite often actually. It seems that he got those patterns with the "official" client and with Azureus.
When are ethical issues not directly derived from self interest? The issue with throttling at an ISP level is receiving the service one pays for. Bandwidth shaping for a personal network, deciding what one would like to do with the service they purchased, is an entirely separate issue.