View Full Version : Fluctuating torrent speeds

2007-07-18, 02:01
Has anyone else experienced fluctuating speeds when downloading torrents?
Most torrents for usually maintain a speed of 45-50kbps, however lately the speeds have been rapidly fluctuating anywhere between <1kpbs (like 500b/s) and around 48kbps.
This may be a problem with my ISP, as it seems to return to normal after a few days, but I'm just curious if anyone else has experienced the same problem.

2007-07-26, 00:09
Unluckily, torrents tend to be pretty random. While they're still more reliable than some other methods of P2P, when there's a low seed to peer ratio, you're bound to get a lot of random results. Also, it doesn't depend solely on seed to peer ratio--you might as well not be connected to the single seed in a torrent with 500 peers and be getting a constant speed of 100 KB/s. It really depends on a lot of factors, which are too many to enumerate, and many of them can't be measured directly anyways.

So yeah, it's pretty normal.

2007-07-29, 07:35
i experienced what you described too... oftenly it occurs when there's only one seeder for that particular torrent and your download speed > seeder's upload speed or when the single seeder is sending redundant pieces

mukansa monkey
2007-07-29, 12:53
This depends an awful lot on what time frame your average speed is occurring over. If you're talking about the value over a minute or so, then you're probably in the situation where ther's very few people on the torrent and so you're sometimes idling waiting for someone else with a slow connection to get round to sending you a piece. However, if this is happening in a torrent with lots of active people, over longer periods of time, chances are good that you've made a mistake in your software settings.

The basic problem that I see lots of people doing is not limiting their # of upload slots (how many people they upload to at once). When you're trying to upload to too many people at the same time, you're sending so little to each individual person that their software decides that you're useless/broken and stops replying to you or even disconnects you.
So what you want to do to prevent this is limit your upload slots to 2 X your connection's upload limit in hundreds of kb (rounded up). I have a cable connection with 768kb upload speed, so round that up to 800, X 2, and I've got 16 maximum uploads at once. That results in an average 5KB+ upload per person I'm connected to. This speed keeps all the other machines I'm uploading to convinced that I'm a good leecher, so I'm getting downloaded to quite consistently. If you have an older DSL connection with 192kb upload, set your max uploads to 4. In fact, you can use BT moderately successfully on a 56kb modem, if you set your upload slots to two and cap your upload speed at 3kb/s. BTW, if you use Azureus the upload limit is set in Preferences/Transfer, the line is called Max upload slots per torrent default. Dunno about other software, some of the more minimalist implementations may not let you control this variable.

Lest you think that this sounds like a minor nitpicky issue, there are software hacks out there that are designed to let you download quickly without uploading much (or in BT terms, not playing well with others). These work by uploading to as many people as possible just barely enough to avoid being flagged as a bad uploader, while hoping that in the meantime those people download to them far more than is uploaded. And naturally they stop the torrent the moment it's complete. When I see my softare uploading to someone at 20+KB, and they're uploading to me at 500B, I assume they're using a software hack (usually BitComet) and I apply the Kick and Ban button.

If you want to maximize your long-term downloading, upload in a way that makes other clients happy.

2007-07-30, 01:37
Either not enough peers or peers have an upload limit. Think about 1 seed seeding a whole bunch of people, the seed will either split it evenly or seed one at a time. And when there are a bunch of seeders, chances are they have upload caps and can't upload anymore than that.

YahooDSL, my isp, has a 40kb/s upload cap, I can't touch 50kb/s but my download can reach 190kb/s but I have to put my upload cap at 30 kb/s.

So I'm saying is, try fiddling with your upload/download caps and see if there is any change. Be sure to enable port forwarding and all those tiny tinkering and if your downloads still fluctuates, it is due to the peer situation I mention above.

2007-07-31, 20:48
I'll agree with something tritoch said.

Oftentimes when I'm downloading a new torrent and there is a seeder that's downloading with a very fast rate >300kb/s, I'll notice my speed peaks at >500kb/s then drops down to 20kb/s relatively quickly. If I lower my upload speed a bit 60kb/s to 50kb/s or 40kb/s I can sustain my download at 500kb/s.

2007-08-08, 20:22
YahooDSL, my isp, has a 40kb/s upload cap, I can't touch 50kb/s but my download can reach 190kb/s but I have to put my upload cap at 30 kb/s.
This is because Tritoch is using an ADSL connection. The A in ADSL stands for Asynchronous, which just means that the connection isn't made for data going both ways - up and down. With ADSL, if you start to saturate your upstream connection (begin reaching your maximum upload speeds), it'll begin to cut into your download speeds pretty harshly. BitTorrent generally rewards you for uploading faster, though, so ADSL users are a damned lot in a sense. Experiment with your upload caps to find the sweet spot: the upload rate that is the highest number you can do without stunting your total possible download speed.

As a poor example from a few years ago, I used to be on a 128 kbps (roughly 16 kbs) up, 768 kbps (roughly 94 kbs) down connection. I could upload at 13 kbs max and still hit the upper 80's for download. Once I trespassed and boosted my upload any further, my download would instantly drop to 20 kbs and would not go above it.