Re: Can P2P applications learn to play fair on networks?

[Joel Jaeggli <joelja () bogus com>]

Jim Popovitch wrote:
> On Sun, 2007-10-21 at 22:45 -0400, Geo. wrote:
> > Second, the more people on your network running fileshare network software 
> > and sharing, the less backbone bandwidth your users are going to use when 
> > downloading from a fileshare network because those on your network are going 
> > to supply full bandwidth to them. 
>
> Hmmmm... me wonders how you know this for fact?   Last time I took the
> time to snoop a running torrent, I didn't get the the impression it was
> pulling packets from the same country as I, let alone my network
> neighbors.
>
> -Jim P.

http://www.bittorrent.org/protocol.html

Peer selection algorithm is based on which peers have the blocks, and
their willingness to serve them. You will note that peers that allow you
to download from them are treated preferentially as far as uploads
relative to those which do not (Which is a problem from the perspective
of comcast customers).

It's unclear to me from the outset, how many peers for a given torrent
would be required before one could place a preference on topological
locality over availability of blocks and willingness to serve.

The principle motivator here is after all displacing costs of downloads
onto a cooperative set of peers where it's assumed to be a marginal
incremental cost. Reciprocity is a plausible basis for a social
contract, or at least that's what I learned in Montessori school.