Strange bandwidth problem

**Cruel** · March 26th, 2005, 06:19 AM

Hi,

Whenever I download files through BT it seems like it's taking up all my bandwidth. What I mean is that if I use another program to download files at the same time, all the downloads are greatly slowed down.
Now this would be understandable if BT was in fact downloading full speed (i.e ~200k since I'm on a 2meg), but the strange thing is that most of the time, my gloabl BT download speed doesn't exceed 100~120k, therefore there should be 100k left for other downloads.

The first strange fact is thus that BT never goes full speed (not even over 130k), even with properly seeded files.

Second, if I download more than one or two files on BT, they would both be quite slow (say 20k each) whereas if I download only one it would be quite faster.

Then the third problem as I said before is that if I use another program to download at the same time, all downloads would greatly slow down, without even reaching the maximum bandwidth, or even near it.

To make it clearer, I'll give you an example:

Say I'm downloading a file through mIrc from a fast bot, it reaches 200k easy - no problem.
Then I start BT, launch a download; what happens is that the mirc download drops to 20~30k and BT reaches 100~120k max.

I hope you understand what I mean. This problem is really annoying.
I have used many different BT clients and they all showed the same behaviour, with slight differences in speed from one another. My port forwarding is ok, I even configured different ports because I know some ISPs block/limit certain p2p default ports. I'm using an old D-Link dsl504 dsl modem/router (10/100). Windows xp sp2 with the half-open connections patch applied. I've tried different amounts of max connections BT uses, no real difference. NIC is a 3Com 3C905C-TX although I doubt the problem comes from there.

Any ideas suggestions greatly appreciated

**ourthing2** · March 26th, 2005, 06:37 AM

limit your upload speed to 50%-80% max capacity (depending on number of connections)

**Cruel** · March 26th, 2005, 07:06 AM

Done that already :(

**ourthing2** · March 26th, 2005, 08:02 AM

did you do it right? did you confuse kb/s for kB/s? did you use your max download speed as your max upload speed? example: i have a 3MiB/s download speed, but only a 256kb/s upload speed so i have to limit upload speed to between 20-28 kB/s so i leave room for ACKs to get out. otherwise my downloads crawl.

EDIT: on the other side of the coin, if you limit your upload speed too much your downloads will suck because BT has built in leech resistince.

Originally Posted by http://en.wikipedia.org/wiki/Torrent

BitTorrent gives the best download performance to the people who upload the most, a property known as "leech resistance", since it discourages "leeches" from trying to download the file without uploading it to anyone. (Although, confusingly, when used in opposition to "seeds" or "seeders" as in "S/L ratio" (meaning "seed/leech ratio"), "leecher" only means someone who hasn't downloaded the full file yet.)