Institute of Electrical & Electronic Engineers
Hierarchical unstructured Peer-To-Peer (P2P) networks for file sharing systems such as Gnutella and Kazaa have made a tremendous achievement in the last decade. However, while these P2P networks can be tolerant of churn, i.e., the dynamics of peer participation and departure (or fault), there still remains the issue of vulnerability to Denial of Service (DoS) attacks, i.e., the highest degree peers are removed. In this paper, the failures are modeled in terms of removal of peers from the network to assess the stability of hierarchical unstructured P2P networks. In order to overcome this shortcoming of these P2P networks, the authors propose a bimodal network based on bimodal degree distribution which is tolerant to both churn and DoS, and an optimal topology.