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Speed bursts and then slows down again


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I'm running into a strange problem when downloading a torrent. My download speed hangs around 200 kB/s (quite low, I'd say) and then for 20-30 seconds it bursts to 1200 kB/s or higher (much better!).

I'm only running 1 download. Said download has 286 seeds and 461 peers, but it appears I'm only using 46 and 48, respectively.

NAT port forwarding through uPnP seems to be OK.

Not sure if related or not, but the auto upload limit sometimes drops to 0. Does not seem to coincide with changes in download speed.

Obviously my connection can handle the higher speeds but something is slowing it down. How can I begin to debug this issue?

Provider: FIOS

Rated d/l speed: 15 Mb/s

Rated u/l Speed: 2 Mb/s

uTorrent set to auto speed

Upload Limit: 17.0 kB/s

Connections: 125

Max active torrents: 15

Upoad Slots: 35

Connections (global): 900

Max active downloads: 15

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Hah, Hah. I'll be the first to admit, I don't understand all the settings! Or rather I understand what each setting means, but not how it plays into uTorrent performance. I guess in my particular case I don't understand exactly how varying the upload speed affects the download speed. I assume it has to do with the torrent trying to keep a good up/down ratio? And the number of connections I guess is the sweet spot between as many sources as possible for data flow vs. the overhead associated with each source.

Oh, how embarrassing! I just noticed below in my original post, my upload limit was 170 kB/s not 17! So my speed setting was close to what you propose. Though my slots may be a bit high. I'm reducing my slots as well as the number of connections to see if that makes a difference.

Thanks for your help, I'll try the settings in your speed guide.


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Upload slots times max active torrents should never be more than about 1/3 of upload speed max.

That's how fast you're uploading to other people.

And many people/peers won't return the favor (giving you download speed) unless you're uploading faster than 3 KB/sec to them.

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Got it. It's not so much the overall upload ratio on my end, as it is the upload speed ratio to a specific peer. That makes sense.

Unfortunately I made the suggested changes, and I still saw similar behavior, with download speeds at around 200 kB/s on average with small 10-20 second bursts up to 1000+ kB/s

I made sure that there was no other network activity in my household (there wasn't). The torrent in question was 1Gb so there was enough time for the peer connections to "stabilize" and not keep changing too much.

Once again, thanks for your help! :)


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