[e2e] Are we doing sliding window in the Internet?

Arnaud Legout Arnaud.Legout at sophia.inria.fr
Tue Jan 9 01:07:07 PST 2007


Tim Dorcey wrote:
> I wonder how much BitTorrent performance is due to his effect?  Might it do
> almost as well if a receiver opened up multiple TCP sessions to the best
> single source?
> I get the point that accessing multiple sources simultaneously deals with
> asymmetry in upload/download speeds.  But, something makes me think this
> washes out in the aggregate if enough torrents are running.  I am ignorant
> on actual network technology though.  Is the asymetric upload/download speed
> common with consumer broadband a function of the last mile link technology?
> Or, something else?

This is not the point with BT. It is not a web client doing parallel 
download to open servers. It is
a P2P protocol that manages to enforce cooperation among selfish peers. 
This is the main reason of its
efficiency. If you want to get data you have to give data. The faster 
you give, the faster you receive, thus a
strong sharing incentive.

If you are interested in you can get papers on experimental evaluation 
of BT from my web page.

Concerning parallel download, you can read this insightful paper:
P. Rodriguez, W. Ernst Biersack., "Dynamic Parallel-Access to Replicated 
Content in the Internet". In IEEE/Transactions on Networking, August 
2002 (Also in IEEE/Infocom 2000)/

/In particular the authors evaluate parallel download from a single 
source or from multiple sources.
The major conclusion is that with dynamic parallel download you don't 
have to know who is the best server.
This best server can even change with time, this is transparent and 
still optimal with dynamic parallel download.


Arnaud Legout, Ph.D.

INRIA Sophia Antipolis - Planète  Phone :
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