[PLUG] Torrents of confusion

[John Jason Jordan]

On Thu, 15 Mar 2007 15:45:52 -0700
"Jason Martin" <nsxfreddy at gmail.com> dijo:

> > > What is sucking up my bandwidth?

> > Probably the uploads, believe it or not.  TCP requires acknowledgments
> > to operate correctly and includes a backoff mechanism when it detects
> > congestion based on drops and retransmissions.  If your uploads are
> > sucking up all your upstream bandwidth (which is less than downstream
> > bandwidth for most broadband connections), then ACK messages will get
> > lost/dropped, and congestion control will kick in.
> >
> > Bittorrent is a great concept, but unless you have a router that does
> > quality of service traffic shaping, bittorrent uploads will definitely
> > kill your outbound traffic speeds, and by doing so will also kill your
> > download speeds.
> 
> I should add that your bittorrent client should have a mechanism to
> rate limit upload speeds, so you can set it to something below your
> upload speed for your broadband connection.  Remember to save room for
> TCP/IP/Ethernet/etc. headers, so do something like 50%, which will
> leave room for other traffic (i.e. email and http) and traffic
> overhead like headers.

Thanks, that was a big help. Ktorrent's options are the following, together with what the defaults were when I opened the settings page ("0" is unlimited):

Queue manager
	Max downloads	0
	Maximum seeds	0
Preferences
	Max connections per torrent	0
	Global connection limit		0
	Maximum upload rate		0
	Maximum download rate	0
	Port						6881
	UDP tracker port			4444
	Number of upload slots		0
	Max share ratio			0

I changed the Maximum Upload Rate to 50 and it didn't make any difference. Then I dropped it to 25 and it made a big difference -- everything else was working much better, plus the download rate on F7-test2 went from an average of 25K/s up to 60+K/s. Finally, I set the maximum number of upload slots to 10 and the Maximum Upload Speed back to 50, and it seemed to be the same. Then I left the slots at 10 and dropped the upload speed back to 25. That was even better.

So now I guess I need to tweak these settings to maximize my own download while maintaining good torrent citizenship. Thanks for the pointers. Some day I may figure this all out.