Enforcing path uniqueness in internet routing

Often an IP network administrator will desire to provision unique paths for traffic demands while avoiding network congestion. Under destination based shortest path protocols this must be achieved indirectly via careful selection of link metrics. We demonstrate that current approaches to metric optimisation cannot reliably produce such unique-path routings. We present two methods of enhancing the capability of local search algorithms for optimising these metrics to produce unique-path solutions: a more intelligent move operator and adaptive penalisation schemes. These approaches are evaluated on four real-world IP backbones, and are shown to reliably produce unique-path routings. By appropriate choice of parameters, unique-path solutions may be found either quicker or of better quality than those produced by fixed penalty schemes.