Reliable response delivery in peer-to-peer systems

Unstructured peer-to-peer (P2P) system is the prevalent model in today's P2P system. In such systems, a response is sent along the same path that carried the incoming query message. To guarantee the anonymity of the requestor, no requestor information is included in the query message and each node in the query incoming path only knows its immediate neighbors who sent the query request to it. This mechanism introduces response loss when any one node or connection in the path fails, which is a general case in the P2P system due to its dynamic nature. In this paper, we aim at addressing the response loss problem and present three techniques to alleviate this problem: redundant response delivery (RRD) scheme as a proactive approach, adaptive response delivery (ARD) scheme as a reactive approach, and extended adaptive response delivery to render ARD to function in an unstructured P2P system with limited or no flooding based search mechanism. With limited traffic overhead, all three techniques reduces response loss rate by more than 65% and they are all fully distributed.