Safari: A Scalable Architecture for Ad Hoc Networking and Services

Within little more than a decade, digital information and the Internet have assumed a critical role in virtually all sectors of society, including education, commerce, science, government, and entertainment. However, today's Internet is dependent on wired or cellular wireless infrastructure. This dependence limits the reach of digital communication to regions of the world where the required infrastructure is technically and economically feasible; at the same time, it renders the network vulnerable to disasters and attacks that threaten this fixed infrastructure. This proposal aims to develop technologies to reduce the dependence of digital communication on wired and cellular wireless infrastructure, thus extending its reach into underdeveloped parts of the world and economically disadvantaged part of society and increasing its resilience to natural disasters, acts of war, or terror attacks on its physical infrastructure. The work exploits synergies between two areas of research that have enjoyed dramatic advances in recent years, but have to date mostly worked independently: (1) ad hoc networking, and (2) decentralized, self-organizing distributed systems. We have assembled a team of experts in each of these areas that will jointly tackle the major technical challenges towards a network architecture that exploits infrastructure when it is available but does not depend on it: Self-organizing network hierarchy: We will develop a novel, self-organizing buoy protocol that recursively subdi- vides the network into an adaptive, proximity-based hierarchy of cells. The cell hierarchy provides the foun- dation for scalable routing and provides a low-overhead, proximity-based overlay structure that can be used to support network services. Periodic broadcasts from buoy nodes in each cell efficiently disseminate aggregated location, addressing, and routing information. Scalable ad hoc network routing: Based on the buoy protocol, we will develop an ad hoc network routing architec- ture for mobile and stationary devices that scales to at least tens of thousands of nodes. Nodes maintain only a small amount of routing state that is logarithmic in the size of the network, in exchange for a slightly longer route length. Nodes maintain their routing state passively by listening to buoy broadcasts, which results in very low routing overhead. The per-node space and message requirements of the protocol grow at most logarithmically with the size of the network. Self-organizing network services: We will develop self-organizing, robust, and secure network services that exploit the hierarchical overlay structure of the buoy protocol. Basic naming, host configuration and network time services will ensure the operation of the network in the absence of fixed infrastructure servers that provide con- ventional DNS, DHCP and NTP services. Other self-organizing services will provide email, instant messaging, storage, and content distribution in the absence of a server infrastructure, manual administration, high-capacity backbones or trusted entities. Our approach builds on foundations from p2p systems, but takes advantage of the hierarchical, proximity-based low overhead overlay structure provided by the buoy protocol to provide a solution suitable for ad hoc wireless environments. Integrated ad hoc network architecture: We will develop a network architecture that will integrate wired and wire- less networks, infrastructure-based, and self-organizing services. The architecture takes advantage of existing infrastructure when and where available, without depending on its presence. In the wake of a disaster, the ar- chitecture will allow remaining islands of surviving infrastructure to self-organize jointly with wireless, mobile components to recover and resume connectivity and emergency network services. Similarly, the architecture will allow the integration of islands of wired infrastructure via wireless ad hoc communication in developing countries. The intellectual merits of this work include the development of the science and technology to meet these chal- lenges; we will evaluate theoretical results, algorithms and protocols through analysis, simulation, and experimental evaluation of prototype implementations; disseminate the results via publications, industrial collaborations, and stu- dent training; and to distribute software artifacts for evaluation and use by industry and the research community. The broader impacts of this work include the development of technologies that will substantially increase the resilience of digital networks to physical disasters or attacks and that will extend its reach into economically disadvan- taged parts of society and underdeveloped parts of the world. Educational impacts include the training of students and research personnel and outreach to educational institutions not historically involved in research.