[p2p-hackers] Using UDT for swarming

Serguei Osokine Serguei.Osokine at efi.com
Tue Jan 25 18:32:35 UTC 2005


	People, does anyone have an opinion about UDT?

http://www.ietf.org/internet-drafts/draft-gg-udt-01.txt
http://www.ncdm.uic.edu/papers/udt-protocol.pdf
http://www.ncdm.uic.edu/papers/udt-control.pdf

- at the first glance it looks like it might be pretty relevant for
the swarming transfers, since it tries to maintain the fairness in
the bandwidth allocation between multiple data streams with very
different RTTs. That is something that TCP cannot do, and I have
a suspicion that this issue might be one of the reasons of why
BitTorrent works wonderfully when you have just one file to upload,
but as soon as you get multiple simultaneous uploads, thing go sour
pretty fast (i.e. Exeem and most of the P2P apps) - you start seeing
very slow streams and such. 

(Actually, I'm mentioning swarming just because it tends to increase
the number of concurrent uploads system-wide; even without it, the
concurrent uploads have always been a problem in any P2P system I can
think of, with a possible exception of Onion Networks - I'm not sure 
how well does Justin handle concurrency.)

	Anyway - did anyone try UDT or at least looked into it? Greg,
LimeWire uses something much more simple, correct?

	Best wishes -
	S.Osokine.
	25 Jan 2005.



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