Browsing by Author "Ngan, Tsuen-Wan (Johnny)"
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Item Incentives and fair sharing in peer-to-peer systems(2004) Ngan, Tsuen-Wan (Johnny); Wallach, Dan S.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.Item Providing incentive to peer-to-peer applications(2009) Ngan, Tsuen-Wan (Johnny); Wallach, Dan S.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.