Davide Cherubini - PhD Thesis - UniCA Eprints

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Chapter 7LP Model Tests & ResultsThe first optimization model presented in the last chapter, makes use of IS-ISrouting protocol in combination with explicit MPLS LSPs in order to find the besttraffic flow distribution. The objective function minimization process involvesalso additional survivability constraints that guarantee the delivery of the trafficin case of single link failure, using the link restoration technique performed by theunderlying IS-IS protocol.In this chapter the results of tests performed over this model are shown and, asbenchmark networks, three different topologies have been used.Two of them are synthetic networks while the third is a real backbone network.At the beginning of the chapter a short description of the implementation and ofthe software used to solve the LP model is given.7.1 Model implementationThe pre-testing phase has required the implementation of a C++ code reproducingthe behaviour of the IS-IS routing protocol. The instances of the problemhave been prepared using the Jones Lustig format [14] and have been read usinga service class for Multicommodity Min Cost Flow solvers called “Graph”[11]. A C++ function has been also implemented, which prepares the matrixrepresenting the constraints of the MMCF problem passing it to an Open sourcesolver called OsiSolver [16]. A further C++ class to decompose the aggregatedper source flows has been implemented.65
7.2 The highly meshed network7.2 The highly meshed networkThe first meaningful test of the model has been performed over a randomly generatedsynthetic network composed by n = 8 nodes and m = 36 directed arcs,each of them having a maximum capacity of 1000 Mbps. The total number ofcommodities is n · (n − 1) = 56 flows and the corresponding model involves 345variables and 422 constraints.The characteristics described are summarized in Table 7.1, while the logical topologyis depicted in Figure 7.1.Nodes 8Arcs 36Flows 56Variables 345Constraints 422Table 7.1: Characteristics of the synthetic networkFigure 7.1: Logical topology of the synthetic networkThe traffic matrix has been randomly generated aiming to slightly “stress”the network in case of single link failure.As “default” configuration, the solely IS-IS routing protocol has been considered.66
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AcknowledgementsThis dissertation w
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AbstractThis dissertation investiga
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CONTENTS7.4 The Real ISP’s Italia
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LIST OF FIGURES7.3 Default metrics
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1.2 Objectives of the dissertation2
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Chapter 2Basic knowledgeThis chapte
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2.1 Understanding IS-IS• A = sour
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2.2 Understanding MPLS Technology2.
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2.2 Understanding MPLS TechnologyTh
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2.4 Restoration SchemesHowever, fai
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Page 57 and 58: 6.2 Graphs and Network FlowsWhere B
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Page 65 and 66: 6.4 LP modelsEquation 6.32 is the o
Page 67 and 68: 6.4 LP modelsmalized as follows:z =
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Page 73 and 74: 6.4 LP models∑f∈Fx f,lij⎛⎝i
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Page 97 and 98: REFERENCES[14] Jones Lustig Format
Page 99 and 100: REFERENCES[40] A. V. Fiacco and G.
Page 101: REFERENCES[61] A. Nucci, B. Schroed
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Davide Cherubini - PhD Thesis - UniCA Eprints

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