Scale-free Overlay Structures for Unstructured Peer-to-Peer Networks

In unstructured peer-to-peer networks, the overlay topology among peers is a crucial factor in addition to the peer/data organization and search. The scale-free networks generated by the preferential attachment (PA) model have been widely described in previous researches. However, the PA model is incomplete to account for the robustness of real network. In this paper, the HLD and HHD models of scale-free overlay structures for unstructured peer-to-peer networks are proposed. With the identical degree distribution and network size in the models, we discuss the structural robustness and fragility as well as the dynamic changes of load intensity when nodes are successively removed under various attack strategies. Experimental results show that these two models are better than PA model in robustness and load-intensity.