Robustness of Path-Vector Protocols without Independent Route Ranking

Recent work has presented theoretical frameworks that rigorously model the behavior of path-vector protocols [6, 7, 13], which are primarily used for inter-domain routing on the Internet. We expand the scope of these to include protocols with route-selection procedures that cannot be captured by a per-node linear order on paths; in particular, our generalized model captures the use of commonly deployed route attributes such as MED, which is used to fine-tune routing between networks that share more than one interconnection. Using the model, we give the best-known sufficient condition guaranteeing robust convergence of path-vector protocols in the generalized case and discuss its applications to protocol design.