Dijjer and Freenet (RE: [p2p-hackers] clustering)

Serguei Osokine osokin at osokin.com
Sun Mar 19 21:31:15 UTC 2006


On Sunday, March 19, 2006 Oskar Sandberg wrote:
> ...the network with 20 links undergoes a phase transition between
> 500 thousand and one million nodes, after which it doesn't work 
> at all (this behavior isn't surprising).

	It is to me. How come it is significantly more than square, 
and doubling of the number of nodes increases the path by a factor 
of *thirty*?

	If I understand things correctly, Chord, for example, would have
about 19 steps at 512,000 (with 19 links, mind you), and 20 steps at
one million - having the same 20 links that your simulation of Dijjer
does. This result of 472 is *extremely* counterintuitive (I'd expect
to see 19-20 at most), and desrves some explanation. Frankly, at the
absence of other data, the simulation bug seems to be the most likely
explanation. 

	Best wishes -
	S.Osokine.
	19 Mar 2006.


-----Original Message-----
From: p2p-hackers-bounces at zgp.org [mailto:p2p-hackers-bounces at zgp.org]On
Behalf Of Oskar Sandberg
Sent: Sunday, March 19, 2006 7:11 AM
To: Peer-to-peer development.
Subject: Re: Dijjer and Freenet (RE: [p2p-hackers] clustering)


Oskar Sandberg wrote:
> To put actual numbers to this, I did simulations of point to point 
> routes using the same algorithm that I think is being used in Dijjer 
> (the one described in my thesis, with 20 shortcuts, but without using 
> "local" links):
> 
<>
> 256000  12.572815
> 512000  15.743066

I let this simulation run further, and here are the results the next 
results:

Run size: 1024000
(474 of 10000 successful: 0.0474)
(Mean Steps: 471.88397)

This means that the network with 20 links undergoes a phase transition 
between 500 thousand and one million nodes, after which it doesn't work 
at all (this behavior isn't surprising). So if the network should grow 
to over half a million nodes, you definitely need more than 20 edges 
(and caching won't help).

// oskar
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