iBGP Deceptions: More Sessions, Fewer Routes
Internal BGP (iBGP) is used to distribute inter-domain routes within a single ISP. The interaction between iBGP and the underlying IGP can lead to routing and forwarding anomalies. For this reason, several research contributions aimed at defining sufficient conditions to guarantee anomaly-free configurations and providing design guidelines for network operators. In this paper, the authors show several anomalies caused by defective dissemination of routes in iBGP. They define the dissemination correctness property, which models the ability of routers to learn at least one route to each destination. By distinguishing between dissemination correctness and existing correctness properties, they show counterexamples that invalidate some results in the literature.