A Dependable Cluster-based Topology in P2P Networks

Unstructured peer-to-peer network is a prevalent model in current P2P networks. In general, unstructured P2P model divides the sharing file into many chunks. A peer must search the positions before downloads a chunk. Since a peer does not know the global topology of the overlay network and the distributions of the wanted chunks, what he can do is flooding chunk queries without a proper order when search and download chunks. Additionally, some peers may behavior selfish: leaves network after completed downloading, downloads but not (or limit) its upload. So, the heavy-tail (or long-tail) phenomenon always exists in the unstructured peer-to-peer networks. Some peers cannot complete their download tasks for the scarcity of certain chunks. By combining topology-control and priority-order, this paper proposes a cluster-based model solve the heavy-tail problem. It analyzes the distribution of file chunks and increases the replication speed of the rarest chunks transmitted among the group. Our simulation experiments show the proposed model provide a dependent network topology for a P2P system, and it helps to transmit the rarest chunk efficiently and improve the overall download completion rate.