Traffic Flow Optimization in Networks with Combined OSPF/MPLS Routing

In this paper we address intra-domain routing optimization issues in Internet networks related to a combination of open shortest path first (OSPF) and multi protocol label switching (MPLS) routing protocols. Since MPLS can be combined with any routing protocol there has appeared an idea of coupling IP streams routed via the OSPF protocol and MPLS label switched paths (LSPs) in the same network. Such combined routing is potentially more flexible and efficient than OSPF itself from the traffic engineering (TE) viewpoint. In the paper we present the exact approach to the considered hybrid routing design using a strict mathematical formulation of the underlying optimization problem, and also a heuristic approach decomposing the problem into two subproblems solved with evolutionary algorithm and simulated allocation. The effectiveness of both approaches is illustrated by means of a numerical study.