Help needed! My network slows to a crawl when running a torrent

[JDub02]

There are 3 computers being a Microsoft router sharing a RoadRunner cable modem connection. Normal speeds are from 200-300K down.

Well, my roommate is a fan of bitorrent and any time he starts pulling something down, all the downloads slow to sub 50K levels.

Now his down is showing 50k as well, but his up is around 40k which I believe is maxing out the connection.

Any idea on how we can keep our download speeds high while a torrent is running?

 

[JDub02]

been reading that I need to somehow cap the upload bittorrent stream. any suggestions for programs that can do this?

 

[Crusty]

Tell him to use Azeurus and have him cap the upload on it.

 

[ColdZero]

In BitTorrent, you also upload at the same time as you download. While your download may be 200-300, your upload may only be a few KB, usually around 20k for cable modems. In the TCP/IP stack there is something called sliding window. What happens is that your computer waits for a certain amount of traffic before sending an ACK to the sending computer telling it that you got everything ok. The sending computer however will not send more traffic than the size of your window. If it doesn't recieve an ACK before this happens, it will stop transmission until it gets that ACK. When your roomate is uploading with bittorrent, they are taking a chunk of your upload bandwidth, if not all of it. The reason your downloads are dropping is because there is not enough upload bandwidth for you to send all the ACKs you need to for the traffic you are recieving. You are only getting enough for about 50k of download. When your roomate stops, you've got more than enough bandwidth to send the ACKs and your download rates will go it. Its part of flowcontrol in the TCP/IP stack, there isn't anything you can do about that. Now what you can do is have yoru roomate limit his upload speed. Some bit torrent clients such as Azeureus will allow you to limit how much they will upload at a given time. Just play around with those settings until you get the download speeds to where they should be.

 

[JDub02]

thanks, guys.