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  1. R. Susitaival, Adaptive Traffic Engineering in MPLS and OSPF Networks, Licentiate thesis, Networking Laboratory, Helsinki University of Technology, 2004 (pdf)(bib)
    Abstract: Traffic engineering refers to performance optimization of operational networks. One task of traffic engineering is load balancing, the idea of which is to move traffic from congested links to other parts of the network in a well-controlled way. If the traffic demands are known, the load balancing can be formulated as an optimization problem. MPLS brings up new possibilities, such as explicit routing, for load balancing in IP networks. It has recently been found that a similar load balancing is possible to implement even in IP networks based on OSPF-routing by adjusting the link weights and the traffic splitting ratios in the routers. A common problem in traffic engineering mechanisms is that the traffic matrix is assumed to be known. This assumption is rarely true and thus adaptive approaches are needed. In this thesis we study adaptive load balancing in both MPLS and OSPF networks based on measured link loads. We propose an adaptive and distributed algorithm for both types of networks that gradually balances the load by making small changes in the traffic splitting ratios of the paths or the routers. In addition, a numerical method is developed to evaluate the performance of the algorithm. The functioning of the algorithm is verified by numerical tests under different networks and traffic conditions. Also the effect of traffic fluctuations on the performance of the algorithm is evaluated. The tests demostrate that in MPLS networks the adaptive algorithm converges rapidly almost to the optimum. In OSPF networks the convergence is slower, but we can still improve the performance of the network significantly as compared to equal splitting.