| In this age of information, new models of information exchange methodologies based on overlay networks are gaining popular attention. Overlay networks provide a logical interconnection topology over an existing physical network. Overlay networks offer benefits such as ease of implementation, flexibility, adaptability, and incremental deployability. Due to the wide range of applications and advantages, formal study of overlay networks is required to understand the various research challenges in this context.; In this thesis, we study two classes of overlay networks namely peer-to-peer networks and wireless ad hoc networks. Our focus will be along two central issues in overlay networks: how to arrive at efficient topologies and how to provide efficient routing strategies.; Peer-to-peer networks have gained a lot of research attention in recent years for various reasons. Despite many advances however, fundamental questions such as how to design deterministic constructions, and how to organize peers of non-uniform bandwidth have remained open. In this thesis, we answer these questions by providing a deterministic overlay topology, Pagoda, that can be used for efficient routing, data management and multicasting. Given the difficulty of arriving at good deterministic topologies in a purely decentralized manner, we also propose a unified methodology to create a large class of overlay topologies via an approach called the supervised overlay networks. We show that this approach also has other advantages such as support for rapid peer join/leave and rapid repair.; For the case of wireless ad hoc networks, we start by providing a model for wireless communication that is much more realistic than the models that are being used in the theoretical community. Using this model, we show how to arrive a sparse spanner construction based on dominating sets. We then use the spanner construction to provide efficient algorithms for broadcasting and information gathering in wireless ad hoc networks. All our algorithms are simple, self-stabilizing and require only a constant amount of storage at any node. Thus, our algorithms are also applicable in a wide variety of scenarios such as simple sensor devices. |
