Hybrid link-state, path-vector routing

Traffic engineering in Internet backbones can be improved by off-line optimization algorithms that automatically configure link weights used by routing protocols. However, with existing protocols large networks often require some type of partitioning in order to scale the routing protocol, and these partitions actually complicate the metrics to the extent that link-weight optimization is no longer practical. In this paper we study how an algebraic specification of a path problem can be naturally decomposed into simpler subproblems where each sub-problem can then be solved independently without changing the global metric being used network-wide. In addition, we go on to study four possible combinations of link-state and distance-vector mechanisms in this setting. In particular, we attempt to clarify the tradeoffs between fast convergence of link-state and low space requirements of distance-vector. The results provide a framework for analyzing existing mechanisms and for designing more reliable and robust routing protocols.