LOUP: The Principles and Practice of Intra-Domain Route Dissemination.

Under misconfiguration or topology changes, iBGP with route reflectors exhibits a variety of ills, including routing instability, transient loops, and routing failures. In this paper, we consider the intra-domain route dissemination problem from first principles, and show that these pathologies are not fundamental-rather, they are artifacts of iBGP. We propose the Simple Ordered Update Protocol (SOUP) and Link-Ordered Update Protocol (LOUP), clean-slate dissemination protocols for external routes that do not create transient loops, make stable route choices in the presence of failures, and achieve policy-compliant routing without any configuration. We prove SOUP cannot loop, and demonstrate both protocols' scalability and correctness in simulation and through measurements of a Quagga-based implementation.