Abstract — Selfish participants in a distributed system attempt to gain from the system without regard to how their actions may affect others. To maintain desirable system-wide properties in the presence of selfish users, designers are increasingly turning to the powerful mechanisms offered by economics and game theory. Combining the two fields of economics and systems design introduces new challenges of achieving incentivecompatibility in systems we can deploy in today’s Internet. In this paper, we explore the interactions between systems and the mechanisms that give users incentives to cooperate. Using findings from recent work on incentive-compatible systems, we discuss several economic mechanisms and assumptions: money, punishment, and altruism. We seek to understand when these mechanisms violate system properties. Among the potential pitfalls we present is a phenomenon we call the price of altruism: altruistic peers can impose a loss of social good in some systems. We also discuss systems-compatible mechanisms that have been used in real, distributed systems, and attempt to extract the underlying design principles that have led to their success. I.

The Internet has been designed as a best-effort communication medium between its users, providing connectivity but optimizing little else. It does not guarantee good paths between two users: packets may take longer or more congested routes than necessary, they may be delayed by slow reaction to failures, there may even be no path between users. To obtain better paths, users can form routing overlay networks, which improve the performance of packet delivery by forwarding packets along links in self-constructed graphs. Routing overlays delegate the task of selecting paths to users, who can choose among a diversity of routes which are more reliable, less loaded, shorter or have higher bandwidth than those chosen by the underlying infrastructure. Although they offer improved communication performance, existing routing overlay networks are neither scalable nor fair: the cost of measuring and computing path performance metrics between participants is high (which limits the number of participants) and they lack robustness to misbehavior and selfishness (which could discourage the participation of nodes that are morelikely to offer than to receive service). In this dissertation, I focus on finding low-latency paths using routing overlay

businesses. • There are too many policies implemented with too few mechanisms.

• Internet-1980 designed to connect disparate technologies; Internet-2008 needs to connects businesses. • Policy and mechanism are often tightly coupled and inseparable, preventing deployment of new (desired) policies