Providing incentive to peer-to-peer applications

Cooperative peer-to-peer applications are designed to share the resources of participating computers for the common good of ail users. However, users do not necessarily have an incentive to donate resources to the system if they can use the system's resources for free. As commonly observed in deployed applications, this situation adversely affects the applications' performance and sometimes even their availability and usability. While traditional resource management is handled by a centralized enforcement entity, adopting similar solution raises new concerns for distributed peer-to-peer systems. This dissertation proposes to solve the incentive problem in peer-to-peer applications by designing fair sharing policies and enforcing these policies in a distributed manner. The feasibility and practicability of this approach is demonstrated through numerous applications, namely archival storage systems, streaming systems, content distribution systems, and anonymous communication systems

Incentives and fair sharing in peer-to-peer systems

Cooperative peer-to-peer applications are designed to share the resources of each participating computer for the common good of everyone. However, users do not necessarily have an incentive to donate resources to the system if they can use the system's resources for free. This thesis presents mechanisms to enforce fair sharing of limiting resources in peer-to-peer systems. Storage fairness is enforced by requiring nodes to publish their storage records and allowing auditing to those records. Bandwidth fairness is enforced by having nodes locally track the amount of data transferred and limiting each node's interactions to a small number of nodes that are proven trustworthy. Thus, a node must provide good service to receive good service. For storage systems to be efficient, nodes should provide overcapacity. Based on an economic analysis of utility functions, we show how the overcapacity parameter should be set and why clustering of the system would benefit users

Building Incentives into Tor

Distributed anonymous communication networks like Tor depend on volunteers to donate their resources. However, the efforts of Tor volunteers have not grown as fast as the demands on the Tor network. We explore techniques to incentivize Tor users to relay Tor traffic too; if users contribute resources to the Tor overlay, they should receive faster service in return. In our design, the central Tor directory authorities measure performance and publish a list of Tor relays that should be given higher priority when establishing circuits. Our system provides an acceptable anonymity tradeoff and improves performance while incentivizing Tor users, across the whole network, to contribute the resources necessary for Tor to better support its users’ needs. Simulations of our proposed design show that conforming users receive significant improvements in performance, in some cases experiencing twice the network throughput of selfish users who do not relay traffic for the Tor network

Abstract Enforcing Fair Sharing of Peer-to-Peer Resources

Cooperative peer-to-peer applications are designed to share the resources of each computer in an overlay network for the common good of everyone. However, users do not necessarily have an incentive to donate resources to the system if they can get the system’s resources for free. This paper presents architectures for fair sharing of storage resources that are robust against collusions among nodes. We show how requiring nodes to publish auditable records of their usage can give nodes economic incentives to report their usage truthfully, and we present simulation results that show the communication overhead of auditing is small and scales well to large networks.