An Adaptive Overlay Network for World-Wide Geographic Messaging

In this paper, we propose an overlay network supporting world-wide geographic messaging. Our approach is based on hierarchical symbolic coordinates like /usa/fl/miami/. Although hierarchical network topologies lend themselves to the implementation of such overlay networks, they may lead to bottlenecks at the root of the hierarchy, long message paths, and inefficient bandwidth utilization. To avoid these problems, we propose an overlay network that adapts its structure to the users' communication patterns by dynamically adding "shortcut" links to the hierarchy leading to a routing mesh. We present an algorithm that carefully selects shortcuts based on their utility to assure short message paths on the one hand and to reduce the induced overhead on the other hand. Through simulations we show that this approach decreases the average path length significantly and reduces network load to about 50% compared to hierarchical routing.