Scalable inter-domain routing architecture

Abstract

As internets grow, both in size and in the diversity of routing requirements, providing inter-domain routing that can accommodate both of these factors becomes increasingly crucial. We propose a scalable inter-domain routing architecture consisting of two major components: source-demand routing (SDR) and node routing (NR). The NR component pre-computes and installs routes that are shared by a significant number of sources. These generic routes are commonly used and warrant wide propagation. The SDR component provides on-demand computation and installation of specialized routes that are not shared by enough sources to justify computation by NR. The potentially large number of different specialized routes, combined with their sparse utilization, make them too costly to support with the NR mechanism. Together NR and SDR address the issue of scaling to global internet sizes without restricting the availability of a diverse set of routes. Routing will adapt naturally over time to changing traffic patterns and new services by shifting computation and installation of particular types of routes between the two components. To complement earlier discussions of SDR design choices [3], this paper evaluates the algorithmic design choices for the NR component in terms of scalability and functionality. In addition, we discuss mechanisms for improving the scaling properties of link-state SDR, and for integrating the two components of the architecture.