[p2p-hackers] Supernodes in the FastTrack network

Saikat Guha saikat at cs.cornell.edu
Tue Mar 7 16:51:33 UTC 2006


On Tue, 2006-03-07 at 17:23 +0100, Jacob Madsen wrote:
> I was reading about FastTrack [...] almost 3 millions users at the
> moment.
> Do someone know of a method to calculate the approx. number of supernodes?

Bunch of really *rough* estimates.

1) In [1], the authors claim that roughly 50% of MSN users are NAT'ed;
such nodes cannot become supernodes [2] (while [2] relates to Skype
specifically, there is some evidence to suggest Skype uses the same
underlying network as Kazaa = FastTrack; also, [2] finds roughly 4
million users, so in the same ballpark). Based on these two, figure
1.5--2M  supernodes as an upper bound. My personal intuition is that it
is much less.

2) In [2], a crawl of the supernode network identified some 250K, only
some of which were online simultaneously. The crawl was not exhaustive.
Figure this is some sort of weak lower bound, with the real number being
higher.

End result: we don't know for sure, but my guess is somewhere between
200K to 2M active supernodes. An order of magnitude doesn't matter much,
right? :P 

A large-scale crawl should yield some tighter bounds. The crawl
methodology is written up in [2].

[1] P Rodriguez, See-Mong Tan, C. Gkantsidis, "On the feasibility of
commercial, legal P2P Content Distribution", In ACM/SIGCOMM CCR, Jan
2006. http://research.microsoft.com/~pablo/papers/CCR.pdf

[2] S Guha, N Daswani and R Jain, "An Experimental Study of the Skype
Peer-to-Peer VoIP System", In IPTPS'06, Feb 2006.
http://saikat.guha.cc/pub/iptps06-skype/

cheers,
-- 
Saikat
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