Some Foundational Problems in Interdomain Routing

The substantial complexity of interdomain routing in the Internet comes from the need to support flexible policies while scaling to a large number of Autonomous Systems. Despite impressive progress in characterizing the various ills of the Border Gateway Protocol (BGP), many problems remain unsolved, and the behavior of the routing system is still poorly understood. This paper argues that we must understand interdomain routing in terms of: (1) intrinsic properties and design tradeoffs of policy-based routing, independent of the specific routing protocol and (2) properties that relate to artifacts in today’s protocol. We pose open questions for the research community that, if answered, should help us understand why BGP’s many problems are so difficult to fix. Understanding the fundamental properties of interdomain routing will help us decide how to make progress, be it making backward-compatible modifications to BGP or designing a radically different protocol.