The Role of Prices in Peer-Assisted Content Distribution

Peer-assisted content distribution matches user demand for content with available supply at other peers in the network. Inspired by this supply-and-demand interpretation of the nature of content sharing, we employ price theory to study peer-assisted content distribution. In this approach, the market-clearing prices are those which exactly align supply and demand, and the system is studied through the characterization of price equilibria. Our work provides two separate steps forward. First, we rigorously analyze the efficiency and robustness gains that are enabled by price-based multilateral exchange. We show that multilateral exchanges satisfy several desirable efficiency and robustness properties that bilateral exchanges such as BitTorrent do not, particularly when considering multiple files. Second, we propose and evaluate a system design that realizes many of the benefits of a price-based multilateral exchange; our design encourages sharing of desirable content and network-friendly resource utilization. Bilateral barter-based systems such as BitTorrent have been attractive in large part because of their simplicity; however, little attention has been devoted to studying the efficiency and robustness lost in return for this simplicity. Our research takes a significant step in filling this gap, both through formal analysis and system design.