On the relationship of node capacity distribution and P2P topology formation

In heterogeneous peer-to-peer (P2P) networks, node capacity distribution becomes a critical parameter in topology formation. Many measurement studies on P2P file-sharing systems point out that users´ bandwidths are actually very diverse, from 56 Kbps modem connections to a few Mbps cable modem connections. Thus, the capacity factor cannot be ignored in the formation of P2P networks. The contribution of this paper is twofold. First, we propose a simple protocol for building P2P topologies such that the connectivity of each peer is based on their capacities to achieve load-balancing. The basic idea for the protocol is to use random walk to assist new incoming peers in selecting their neighbors with a high capacity. This random walk algorithm only relies on local information., and thus is fully distributed. Second, by mathematical analysis and simulations, we investigate the performance of the proposed protocol and show that the topology structure depends heavily on the capacity distribution of the users. The analytical results provide insightful guidelines for overlay network modeling, planning and protocol design based on the node capacity distribution. To the best of our knowledge, this is the first paper that analyzes this relationship.