Super Peer Deployment in Unstructured Peer-to-Peer Networks

Two-layer hierarchy unstructured peer-to-peer (P2P) systems, comprising an upper layer of super-peers and an underlying layer of ordinary peers, are commonly used to improve the performance of large-scale P2P systems. However, the optimal super-peer network design involves several requirements including super-peer degree, network diameter, scalability, load balancing, and flooding performance. A perfect difference graph has desirable properties to satisfy the above design rationale of super-peers overlay network. This paper proposes a two-layer hierarchical unstructured P2P system in which a perfect difference graph (PDG) is used to dynamically construct and maintain the super-peer overlay topology. In addition, the broadcasting performance of the P2P system is enhanced through the use of a PDG-based forwarding algorithm which ensures that each super-peer receives just one lookup query flooding message. The theoretical results show that the proposed system improves existing super-peer hierarchical unstructured P2P systems in terms of a smaller network diameter, fewer lookup flooding messages, and a reduced average delay and the experimental results show that the proposed two-layer hierarchy P2P system performs very well in the dynamic network environment. Keywords-Super Peers, forwarding Algorithms, Peer-to-Peer.