[BitTorrent] Re: TCP vs. UDP

larytet larytet at yahoo.com
Tue Mar 22 15:31:27 EST 2005



indirectly some of the facts support idea of using UDP. 

In real network average performance of TCP can not be exceeded by
proprietary UDP transport, but it can be argued that in some cases
such proprietary protocol can be made efficient "enough" and for some
networks - specifically for fat connections with high latency and
uniformly distributed low packet loss, can beat TCP performance.


--- In BitTorrent at yahoogroups.com, Olaf van der Spek <OvdSpek at L...> wrote:
> larytet wrote:
> > 
> > 20% of peers has connection with latency above 300ms
> > Another problem is geographical location of peers. Peers tend to
> > establish connections randomly creating unnecessary burden for ISPs.
> > 
> > from the article:"Our interest in latencies of the peers is due to the
> > well known feature of TCP congestion control which discriminates
> > against &#64258;ows with large round-trip times.
> > This, coupled with the fact that the average size of &#64257;les
exchanged is
> > in the order of 2-4 MB, makes latency a
> > very important consideration when selecting amongst multiple peers
> > sharing the same &#64257;le."
> > 
> > Amazingly there are peers with 1s latency and more. Clearly these are
> > peers behind dial ups with large TCP packets in downstream queue
> > waiting for delivery.
> > 
> > The article contains lot of usefull statistics. I thought that there
> > are people who did not read it and would be interested in reading it.
> 
> That's certainly true, but I couldn't find the TCP vs UDP bit.
> 
> > --- In BitTorrent at yahoogroups.com, Olaf van der Spek
<OvdSpek at L...> wrote:
> > 
> >>larytet wrote:
> >>
> >>>this article is interesting
> >>
> >>Where does it discuss TCP vs UDP?
> >>And how is the article relevent to BT?
> >>
> >>
> >>>http://www.utsc.utoronto.ca/~rosselet/cscd58/ref05/p2p-measure.pdf
> >>>related to Napster/Gnutella, some measurements of connection latency
> >>>and available bandwidth. 
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> 
> >>>Yahoo! Groups Links
> >>>
> >>>
> >>>
> >>> 
> >>>
> >>>
> >>
> >>
> >>-- 
> >>Olaf van der Spek
> >>http://xccu.sf.net/
> > 
> > 
> > 
> > 
> > 
> > 
> >  
> > Yahoo! Groups Links
> > 
> > 
> > 
> >  
> > 
> > 
> 
> 
> -- 
> Olaf van der Spek
> http://xccu.sf.net/





 
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