"Adding Incentives to Peer-to-Peer Systems"

Speaker: Aviv Zohar
Date: Thursday, 20 December 2007
Time: 2pm
Place: Ross 201

Aviv Zohar and Jeffrey S. Rosenschein

Abstract:

Modern-day peer-to-peer systems rely heavily on the willingness of
users to distribute files to their peers. A selfish user can choose to
download the file and consume resources without uploading in
return. This form of free-riding plagues all currently deployed
systems.

We present a mechanism for a BitTorrent-like system (in which only one
file is being shared) that strongly discourages peers from downloading
a file without sharing it. Our mechanism requires very little
computation, and can easily be implemented in today's peer-to-peer
systems. It is resistant to all forms of manipulation by peers
including the use of multiple free identities and does not require any
coordination between seeds. We analyze our mechanism within a
game-theoretic model and show that with it, a new system equilibrium
is reached in which all peers upload at least some percentage of the
file they are given.