Martin Levac Posted January 14, 2006 Report Share Posted January 14, 2006 Greetings,My connection is 6.5mbs/900kbs (750kBs/112kBs). When I download using simply HTTP of FTP, DUmeter reports about ~5kB/s upload for ~750kB/s DL bandwidth. When I download using uTorrent, DUmeter reports about 35-40kB/s upload for the same 750kB/s DL bandwidth. I understand there's a difference between single source download and multiple source download, more TCP traffic is required for multiple source download. What I don't understand is how come there's so much more TCP traffic for multiple source download. If somebody could explain it to me, I'd figure out what the problem is, if there is a problem.ML Link to comment Share on other sites More sharing options...
1c3d0g Posted January 14, 2006 Report Share Posted January 14, 2006 HTTP/FTP != BitTorrent :| Link to comment Share on other sites More sharing options...
chaosblade Posted January 14, 2006 Report Share Posted January 14, 2006 You are, aware, of course, that bittorrent is about SHARING? When you download http\ftp, you are not sharing anything back with your sources. Perheps you need to read our FAQ and the more general "What is BitTorrent" FAQs before you continue. Link to comment Share on other sites More sharing options...
Martin Levac Posted January 14, 2006 Author Report Share Posted January 14, 2006 An example of what I mean.A torrent with multiple seeds and no peer (http://borft.student.utwente.nl/~adrian/bt.php).All seeds send me data which saturate my connection to about 750kB/s down.No upload bandwidth is used to send data to other peers since there is none to send data to.DUmeter reports 35-40kB/s of upload bandwidth used by uTorrent when it's downloading at max capacity.Is this a problem and can I fix it?ML Link to comment Share on other sites More sharing options...
Ghost21 Posted January 14, 2006 Report Share Posted January 14, 2006 It's sending data that you already have. In other words, it's uploading what data that you have already downloaded. Link to comment Share on other sites More sharing options...
Martin Levac Posted January 15, 2006 Author Report Share Posted January 15, 2006 To whom is it sending data? I'm not connected to any peer.ML Link to comment Share on other sites More sharing options...
wormhole Posted January 15, 2006 Report Share Posted January 15, 2006 lol.. they dont get it.. well, all I can think of is overhead traffic.. you telling them which pice you need and which you have and so on..I started to download a file from that site you posted, to see what I've getting.I'm on a 6000/600kb/s cable connection and it maxed it out at ~750kB/s DL. my UL was at ~20kB/s.. also measured with du-meter. looks like everything is ok..btw. with your 6.5mbit you should get about 800kB/s.. Link to comment Share on other sites More sharing options...
Martin Levac Posted January 15, 2006 Author Report Share Posted January 15, 2006 I tried it with DHT off and I get better results with about 18-20kB/s upload bandwidth used at full speed. I don't have a problem with TCP parameters, I set them for high bandwidth.About my connection, it's TCP over ethernet then TCP over ATM on cable. ATM is the protocol used between my cable modem and the router at my ISP's end, ethernet is the protocol used between my machine and the cable modem and finally TCP is the protocol used between my machine and any other machine I connect to. Of the bandwidth my ISP gives me, only about 87-90% of it can be used for actual data hence the 750kB/s. Nevertheless, I was told that my modem is a bit old and normally can not support such high speeds and another, faster modem was available so I'll look into that.ML Link to comment Share on other sites More sharing options...
-BAR-BAR-BAR- Posted January 15, 2006 Report Share Posted January 15, 2006 what is tha big worry anyways?bit torrent about sending data out toothats tha whole idea, compared to my connectionupload max 30kb download max 62kb!!! and not at tha same time i might add! have to cap upload to about 19 for max down :-(good old uk and tha shite exchanges bt use/limit for us!would be good ta see mine downloadin at 700kb/s Link to comment Share on other sites More sharing options...
Martin Levac Posted January 15, 2006 Author Report Share Posted January 15, 2006 Exactly. I want to upload as fast as I can while still downloading as fast as I can simultaneously. The higher the overhead, the less data I can send back. The more data I send back, the slower my download.ML Link to comment Share on other sites More sharing options...
Firon Posted January 17, 2006 Report Share Posted January 17, 2006 Martin Levac: no, it's not a problem, download creates upload overhead, it's perfectly normal. When I download at 500kb/s+, it uses like 20-30 KiB/s upload Link to comment Share on other sites More sharing options...
chaosblade Posted January 20, 2006 Report Share Posted January 20, 2006 Wow. Never knew the overhead is so huge. But thats definitly the reason. Link to comment Share on other sites More sharing options...
Switeck Posted January 21, 2006 Report Share Posted January 21, 2006 Download Overheads in the form of upload ACK packets are lower if you use a larger MTU (Maximum Transmission Unit - or something like that) value.The normal maximum allowed MTU value is only 1500 bytes, and for special connections (typically ADSL, ATM, PPPoE, etc) can be as low as 1300 bytes.MTU is the maximum size a single data packet can be.Since the headers for each data packet is typically the same amount, you can cram more bits of a file out with less bandwidth used with larger MTU's.From my observations, the ratio of download bandwidth to upload ACKs for that traffic is about 40-50 to 1.So if you're downloading at 400 KB/sec, you need about 10 KB/sec upload bandwidth for ACKs as absolute minimum...even with a MTU of 1500 bytes. Link to comment Share on other sites More sharing options...
Martin Levac Posted January 21, 2006 Author Report Share Posted January 21, 2006 I think it can be reduced even further by increasing the RCV window. I did that but it doesn't make much of a difference with uTorrent since any data being transfered goes through multiple connections simultaneously and uTorrent has its own scheme for ACK and REQ. Each of which are probably using smaller RCV windows just because of the speed at which data is being transfered through each connection.One TCP connection sending me 750kB/s will only really need one ACK per 512kB (that's what I set for RCV window in Win2k and I barely see 5kB/s upload, if that) of data but multiple uTorrent connections sending me the same combined amount of data will probably need as many ACK as there are connections.ML Link to comment Share on other sites More sharing options...
Martin Levac Posted January 24, 2006 Author Report Share Posted January 24, 2006 What about bytes to query for per request (defaults to 16384 in the original BT client)? Does uTorrent scale that with increased speed?ML Link to comment Share on other sites More sharing options...
tumu Posted January 24, 2006 Report Share Posted January 24, 2006 Try latest beta and bt.send_have_to_seed off. Link to comment Share on other sites More sharing options...
Lys Posted January 28, 2006 Report Share Posted January 28, 2006 Try latest beta and bt.send_have_to_seed off.What is the negatives to this option? Seeds don't need to know which part of the torrent you have, but it is enabled by default. Why is this the default? Link to comment Share on other sites More sharing options...
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