A Congestion-Aware Search Protocol for Unstructured Peer-to-Peer Networks

Peer-to-Peer (P2P) file sharing is the hottest, fastest growing application on the Internet. When designing Gnutella-like applications, the most important consideration is the scalability problem. Recently, different search protocols have been proposed to remedy the problems in Gnutella’s flooding. However, congestion due to large query loads from users and peer heterogeneity definitely impact on the performance of search protocols, and this consideration has received little attention from the research community. In this paper, we propose a congestion-aware search protocol for unstructured P2P networks. The aim of our protocol is to integrate congestion control and object discovery functionality so that it can achieve good performance under congested networks and flash crowds. The simulation results show that our protocol can largely reduce a hit delay while maintaining a high hit rate, and the congestion problems such as query loss and system overloading can be effectively alleviated.