Resilient routing using MPLS and ECMP

The increasing commercial importance of the Internet together with a rising number of real-time and mission-critical applications make fast resilience mechanisms a major issue for IP network planning and operation. Current IP-layer rerouting is too slow to meet these requirements. Therefore we propose a new approach combining two protocols readily available in every router: The fast local reaction of the equal-cost-multiple-path extension of OSPF operating on a network with its connectivity enhanced by the introduction of a limited number of MPLS paths in critical areas of the topology. We describe an algorithm for the determination of these MPLS paths and its optimization to obtain an equal loading of the physical network links. Numerical results on the basis of real network topologies show that already a small number of MPLS paths can offer sufficient connectivity for fast protection via ECMP. Furthermore, it can be proven that the bandwidth overhead necessary for this enhanced network resilience is as small as possible.