[p2p-hackers] Re: scalability

[Greg Bildson]

Those suppositions are fairly misplaced as is most academic work on
Gnutella.  I wouldn't believe any (other than Daniel Stutzbach's) academic
papers describing Gnutella.

Partial file sharing is active by default.  Download meshes are in place.
Download chunking (pseudo-random) is in place - not rarest first but
sufficient in many cases.  Many improvements have been made to increase the
awareness and allocation of resources but improvements can still be made.

You are correct that rare file/topic searches are still not great but are
much better than historically and likely better than similar networks.
Dynamic querying does a good job of satisfying popular requests at low cost
and reserving more horsepower for rarer searches.

Efficiency is pretty good.  Bittorrent is a tad verbose in some respects.
The only important things that are not in place in Gnutella are rarest first
and tit for tat.

Thanks
-greg
> -----Original Message-----
> From: p2p-hackers-bounces at zgp.org [mailto:p2p-hackers-bounces at zgp.org]On
> Behalf Of Bryan Turner
> Sent: Friday, December 02, 2005 3:16 PM
> To: 'Peer-to-peer development.'
> Subject: RE: [p2p-hackers] Re: scalability
>
>
> My $.02 on Gnutella,
>
> 	The Gnutella network will scale fine to 2B nodes.  However, I
> believe without interest clustering or intelligent peer selection, it will
> become increasingly difficult to find the data you are interested
> in.  IE: I
> feel the current architecture misses the 'long tail'.  (Note that I am not
> well versed on Gnutella architecture, this opinion is based on papers
> modeling the math behind Gnutella)
>
> 	I like to find the orthogonal axis in a design, P2P has lots of
> interesting scalability axis:
> 1	Scalability in # of nodes
> 2	Scalability in # of objects
> 3	Scalability in size of objects
> 4	Scalability in interest for an object (hot spots)
> 5	Scalability in bandwidth (protocol overhead, efficiency)
> 	etc.
>
> 	BitTorrent captures all but #2, as multiple torrents may require
> redundant connections to a peer, and torrents that share files cannot also
> share swarms (not to mention BitTorrent isn't a content search network).
>
> Gnutella (I believe) doesn't meet #2,3 and partially #4,5:
> 	#2 because it does not cluster related data it will eventually
> 		be overwhelmed with content.
> 	#3 because it performs full-file transfers instead of block
> 		exchanges or partial file transfers
> 	#4/5 because clients don't immediately offer partial downloads,
> 		thus hot spots have a congestion delay measured in
> 		full-file-transfer increments rather than in block
> 		increments (an order of 2 for typical MP3s, easily
> 		reaching multiple days of congestion).
>
> 	A vision for a network that scales along all axis would be Gnutella
> with some structure to improve domain-specific searches, with
> BitTorrent as
> the data transfer mechanism.
>
> Please educate me if I've missed some facet of Gnutella!
> --Bryan
> bryan.turner at pobox.com
>
> -----Original Message-----
> From: p2p-hackers-bounces at zgp.org [mailto:p2p-hackers-bounces at zgp.org] On
> Behalf Of Daniel Stutzbach
> Sent: Thursday, December 01, 2005 3:52 PM
> To: p2p-hackers at zgp.org
> Subject: Re: [p2p-hackers] Re: scalability
>
> On Thu, Dec 01, 2005 at 09:48:45PM +0100, Ronald Wertlen wrote:
> > Gnutella 0.6 (is there a 0.7 protocol, I can't find it?) allows
> > practically anyone to elevate to super-peer, which results in a random
> > (power-law distribtion) network.
>
> Gnutella is not a power-law network.  See my paper on the graph properties
> of Gnutella, presented at the Internet Measurement Conference earlier this
> year:
>
> http://www.usenix.org/events/imc05/tech/stutzbach.html
>
> > Such a network is not going to perform very well as far as recall and
> > precision are concerned, past a certain point. I would be interested
> > to calculate that exact point (but doubting I'll get to it some time
> > soon :-/).
>
> Could you rigorously define recall and precision for me?  I'm not
> sure what
> you mean by these terms.
>
> --
> Daniel Stutzbach                           Computer Science Ph.D Student
> http://www.barsoom.org/~agthorr                     University of Oregon
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