Abstract – Peer-to-Peer (P2P) networks and their applications gain increasing importance in today’s Internet, as already today the majority of IP traffic is caused by P2P applications. Since the upcoming of Napster a lot of research has been done in this area producing interesting and promising results. Still, growing demands like less data rate consumption, faster and more reliable search responses and the development of new applications engage many researchers worldwide. In this tutorial we therefore provide an overview about the area of P2P networking, its basic methods and a classification into unstructured and structured P2P networks. However the focus of this work is put on structured P2P networks, for which we explain in detail the most important routing algorithms. Based on this overview we can provide a discussion of the major advantages and disadvantages of the different P2P approaches, focusing especially on the applicability of P2P networks in heterogeneous environments.

homogeneous nodes on the same overlay. However, realistically nodes on a network are heterogeneous in terms of their capabilities. Because of this, traditional DHTs have been shown to exhibit poor performance in a real-world environment. Additionally, we believe that it is this approach that contributes to a limited exploitation of peer-to-peer technologies. Previous work on super-peers in DHTs was proposed to address these performance issues, however the strategy used is often based on locally clustering peers around individual super-peers. This method of superpeering, however, compromises fundamental features such as load-balancing, resilience and routing efficiency, which traditional DHTs originally promised to offer. We propose a Stealth DHT which addresses the deficiencies of previous super-peer approaches by using the DHT algorithm itself to select the most appropriate super-peer for each message sent by peers. Through simulations and measurements, we show the fitness for purpose of our proposal.

A lot of research papers discussed the Distributed Hash Table (DHT) based p2p algorithms to promise that idle resources may be efficiently harvested. However, p2p systems are composed of components with extremely heterogeneous availabilities and to handle churn, the system will generate the heavy information maintenance traffic to keep the efficiency of the DHT based p2p algorithms. In this paper, we suggest the mobile ID based p2p algorithm to reduce the overhead by exploiting the heterogeneity of participant nodes efficiently. Unlike the DHT based p2p algorithms, the node ID of a node changes according to its characteristic to support the p2p system efficiency and each nodes takes the different responsibility in accordance with its node ID. We classify nodes into the two types according to the characteristics of nodes: the reliable nodes and the leaf nodes. The reliable node has the load-balanced ID to balance the loads and the leaf nodes has the load-free ID to reduce the responsibility. We examine the efficiency of our p2p algorithm via a event driven simulation and show that the information maintenance traffic reduces and the routing process is more efficient. 1.

journal homepage: www.elsevier.com/locate/comcom

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