Bandwidth issues

[Relambrien]

So, a lot of large files or groups of files are shared via BitTorrent now. For instance, I was downloading a Portal speedrun with it the other day.

My problem is that when I use it, even though I may download at less than 100 KB/s, my Internet speed is completely killed. I have a 15mbps line, yet it goes down to less than 2mbps while any torrents are running. And I assure you I don't achieve that speed, more like that ratio. Meaning pages load 7.5x slower than normal. I've tried limiting the download and upload speeds, and that doesn't do anything. This is true of all torrents, regardless of current download speed, content, etc.

I have no idea why it's doing this, or what I can do to fix it, so if anyone could enlighten me as to either of those things, I could really use the help.

My guess is that the majority of bandwidth is being "reserved" for the torrent, but then, wouldn't limiting download and upload fix that? I can't think of anything else.

[Specforces]

Re: Bandwidth issues

Any torrent client I use tends to kill my internet speed.

[sumzup]

Re: Bandwidth issues

Check this out. Try out the settings mentioned there except for encryption, and if it's still slow, it's likely your ISP is throttling torrent traffic, and you should enable encryption.

[charless]

Re: Bandwidth issues

You're seeing the problem if its related to the download/downstream speed you're going at but it's not that. Limit your upload speed to 5-10kb/sec and see if that helps. If you're uploading then that's what's hindering your overall connection.

[Relambrien]

Re: Bandwidth issues

After trying what sumzup recommended, my speed is now 2/3 what it should be, rather than the 2/15 from earlier. So it's five times faster, which is good. I can deal with that. I doubt I'll see any noticeable impact on torrent performance, so everything should work out alright.

EDIT: Further speed testing shows fluctuation between 2/5 and 4/5 almost randomly, and very quickly. Still much better, of course, but a bit quirky.

Now, since I'm really interested in how things work, here's my guess as to why this works. Since torrents utilize p2p technology, a lot of the program involves connecting to and listening to other computers. The settings restricted vastly decrease the number of potential connections, and disables some features regarding the connections themselves. The dl and ul speed limits are there to help ensure that at least some bandwidth can be left over.

I'm no p2p expert, but it seems that when a torrent program runs, it does indeed use up much more bandwidth than what is actively being utilized by the computer, almost as if it's "reserving" it. Limiting the connection potential is more or less equivalent to lessening the amount of bandwidth the client reserves, so more of it is left for other uses.

Is this more or less right?

[sumzup]

Re: Bandwidth issues

I think you have it pretty much correct. There's definitely much more to bandwidth than what one has as a cap for dl and ul speed. It seems to be dependent more on how many peers one is connected to, which makes some sense. To build on your "reserving" theory, it'll take much more bandwidth getting 1 kB/s from 500 peers each than 10 kB/s from 50 peers each; there would be less "room" required for each peer in the latter example.

For those without Relambrien's ungodly connection (I really hate you, btw), the number of connections isn't as big a factor as capping speeds from within one's torrent program, so usually, you just see advice telling one to upload at a lower rate.

Also, speeds (browsing & torrent download) can depend on the client used; uTorrent seems to be the best for Windows, and I think Transmission is a good client for OS X (no one cares about Linux, sorry). A light memory footprint is sometimes just as important a factor as some of the others mentioned.