DynaMO: A Topology-Aware P2P Overlay Network for Dynamic, Mobile Ad-Hoc Environments

Due to the key differences between wired and ad-hoc wireless networks, traditional networking services and techniques are not always easily portable from an infrastructure based network to a wireless environment. One of the most prominent examples is the TCP transport protocol, which performs only poorly in wireless ad-hoc networks. The Peer-to-Peer (P2P) overlay networks recently developed all target the Internet where a lot of performance issues can be neglected or can be completely ignored. In addition, assumptions made for infrastructure based networks cannot be made in an ad-hoc environment, such as a fixed set of nodes which are always available. This article presents a P2P network tailored towards mobile ad-hoc environments. It utilizes proximity information to efficiently generate an overlay structure which reflects the underlying physical network topology. This way, physical routing path lengths stretched by the overlay routing process are reduced. As a novelty it does not rely on a fixed set of nodes and adapts to changes in the physical network topology. A prominent property of the overlay construction process is that the communication overhead is reduced to a minimum. Additionally, the P2P network presented maintains an even Overlay ID distribution which is deliberately given up by some solutions previously developed for wired networks. The basis of this new overlay network is Pastry, a P2P substrate based on the concept of a distributed hash table. Two different bootstrap strategies were developed and analyzed, both explicitly designed to work in dynamic and mobile networks such as ad-hoc networks.