Combating Hidden Action in Unstructured Peer-to-Peer Systems

In unstructured peer-to-peer systems, cooperation by the intermediate peers are essential for the success of queries. However, intermediate peers may choose to forward packets at a low priority or not forward the packets at all, which is referred as peers' hidden action. Hidden Action may lead to significant decrement of search efficiency. In contrast to building a global system with reputations or economics, we proposed MSSF, an improved search method, to help queries route around the peers with hidden action. MSSF does not need to check other peers' behavior. It automatically adapts to change query routes according to the previous query results. Simulation results show that MSSF is more robust than Gnutella flooding when peers with hidden action increase.