Rationality and Self-Interest in Peer to Peer Networks

Much of the existing work in peer to peer networking assumes that users will follow prescribed protocols without deviation. This assumption ignores the user’s ability to modify the behavior of an algorithm for self-interested reasons. We advocate a different model in which peer to peer users are expected to be rational and self-interested. This model is found in the emergent fields of Algorithmic Mechanism Design (AMD) and Distributed Algorithmic Mechanism Design (DAMD), both of which introduce game-theoretic ideas into a computational system. We, as designers, must create systems (peer to peer search, routing, distributed auctions, resource allocation, etc.) that allow nodes to behave rationally while still achieving good overall system outcomes. This paper has three goals. The first is to convince the reader that rationality is a real issue in peer to peer networks. The second is to introduce mechanism design as a tool that can be used when designing networks with rational nodes. The third is to describe three open problems that are relevant in the peer to peer setting but are unsolved in existing AMD/DAMD work. In particular, we consider problems that arise when a networking infrastructure contains rational agents.