iBGP2

The Internet is made of almost $50,000$ ASes exchanging routing information thanks to BGP. Inside each AS, information is redistributed via iBGP sessions. This allows each router to map a destination exterior to the AS with a given egress point. The main redistribution mechanisms used today, (iBGP full mesh, Route Reflectors and BGP confederations), either guarantee selection of the best egress point or enhance scalability, but not both. In this paper, we propose a new way to perform iBGP redistribution in an AS based on its IGP topology, conciliating optimality in route selection and scalability. Our contribution is threefold. First, we demonstrate the tractability of our approach and its benefits. Second, we provide an open-source implementation of our mechanism based on Quagga. Third, we illustrate the feasibility of our approach through simulations performed under ns-3 and compare its performances with full mesh and Route Reflection.