Davide Cherubini - PhD Thesis - UniCA Eprints

6.4 LP modelsdecomposed in order to find the explicit LSP to be imposed in each router.For the sake of clarity, in figure 6.3 the solution of the presented model for abenchmark network is shown.Figure 6.3: Example of solutionAt ingress node A the aggregated flow (deficit) is specified, which is equalto the sum of traffic outgoing from nodes C and D. These values are the givencommodities directly obtained from the traffic matrix.Furthermore, for each arc the solution obtained from the model is indicated.Two possible equivalent solutions of the decomposition algorithm are shown infigures 6.4(a) and 6.4(b).In the first solution 3 flows have been obtained, while in the second the initialaggregated flow has been decomposed in 2 flows.In other words, it is possible to obtain multiple equivalent solution while thenumber of LSP paths to be imposed is significantly different.Unfortunately, a path decomposition algorithm that furnishes a unique optimalsolution for these class of problems does not exist in literature and then itis only possible to obtain multiple solutions, which have to be evaluated in orderto fit further explicit requirements of the problem (e.g. minimize the maximumnumber of LSP).59