Some Peer-to-Peer (P2P) file sharing operation models over asymmetric networks have several shortcomings that may affect system and network performance: data transmission paths are highly redundant wasting a lot of backbone bandwidth, the download throughput in a node may be limited by the the upward bandwidth of other nodes; TCP performance is deteriorated due to the blocking of acknowledge packets on the upward channel. These shortcomings severely impair the efficiency of P2P file sharing as well as network performance. These problems are further complicated by the voluntary nature of P2P: peer nodes are fairly unstable. For similar reasons, when such P2P file sharing paradigm is moving to wireless networks, it may suffer from even worse performance degradation due to many reasons such as lower link reliability, lower bandwidth, and the impairment of TCP protocol.

This paper analyzes these problems mainly from topology and protocol viewpoints and proposes some solution approaches to alleviate some of these problems.