Restructuring peer-to-peer networks

The popularity of peer-to-peer networks has grown tremendously in recent times as aresult of the ever-improving capabilities of host entities at the edge and the ubiquitousreach of the Internet. The growth has fueled the realization of many peer-to-peernetworks in both academia and the commercial arena. Peer-to-peer networks generallyfall into one of these categories centralized systems with server-like entities in thenetwork; unstructured systems with random topology and message routing, andstructured systems with deterministic topology and routing behavior. Surveying themajor peer-to-peer networks in each category, one can conclude that the each of thecategories exhibit very different characteristics and properties from one another.This thesis addresses the problems in the peer-to-peer networking space by employingtwo overarching principles. Firstly, desirable properties of systems in one category canbe adopted by another to achieve restructuring. In short, restructuring involves theinjection of structure into unstructured networks and conversely loosening the rigidity instructured systems. Secondly, as much as possible, participating peers in the networkare designed to be homogeneous in functionality recognizing that they areheterogeneous in capabilities. True to the concept of the peer-to-peer paradigm, thisprinciple keeps participants functioning as fellow peers rather than imposinghierarchical differences in the roles within the network.We describe three contexts in which the issues pertaining to the peer-to-peer networksin view can be addressed by applying the principle of restructuring. For the MobileAgent Peer-to-Peer architecture, we adopt centralized concepts into the unstructuredpeer-to-peer network while maintaining homogeneity in functionality through the use ofmobile agents. The architecture shields excessive traffic from peers with limitedresources and allows more capable peers to share others burden. Through the use ofmobile agents, logical hierarchy is avoided and thus the second overarching principle ofhomogeneity is preserved. For Gnutella Clusters, concepts from the structured systemsare adopted to facilitate the formation and maintenance of clustering in unstructurednetworks. Clustering limits the amount of flooding in the network and thus conservesbandwith. The clustering algorithm is decentralized to all peers, and does not need a setof participants to have special functionality thus preserving the generic nature of allpeers. In Autonomic Decentralized Service Directory platform, structure is releasedfrom the underlying Chord network to provide better support for service registration andsearching. The strict requirements for deterministic routing and lookup whichcharacterize structured systems are granted some leniency for the ability to avoidmisbehaving nodes and provide incentives for peers to behave properly