Abstract
Semi-rings have been used in the past thirty years as a general framework in which to describe routing problems and routing algorithms. Some of the semi-ring axioms can be relaxed to arrive at "routing algebras" (Sobrinho 2003), which can model the very complex poilcy-based routing used in the Internet today. Metarouting is centered around defining a meta-language for routing algebras --- a language where algebraic properties (such as monotonicity) needed for convergence guarantees can be automatically derived much like types are derived in programming languages.