Davide Cherubini - PhD Thesis - UniCA Eprints

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2.1 Understanding IS-IS(a) IS-IS single path(b) IS-IS multiple equivalent pathsFigure 2.1: Single and multiple pathsThe main disadvantage of a link state routing protocol is that it does not scalewell, as more routers are added to the routing domain. In fact, by increasing thenumber of routers, the size and the frequency of the topology updates increase. Inthe meantime also time taken to calculate end-to-end routes increases. This lackof scalability means that a link state routing protocol is unsuitable for routingacross the Internet at large. That is the reason why IGPs only route traffic withina single AS.7
2.2 Understanding MPLS Technology2.2 Understanding MPLS TechnologyWhat is what?MPLS (Multi-Protocol Label Switching) combines the speed and performanceof packet-switched networks with the intelligence of circuit-switched networks toprovide a best-of-breed solutions for integrating voice, video and data.MPLS is an IETF standard built on the efforts of speeding up the managementof packets into the inner nodes of the network, assigning most of the complexfunctions to the edge routers. Moreover, with its Traffic Engineering extension,MPLS is able to facilitate resource allocation and to realize particular type ofservices.The MPLS architecture lies at an intermediate level of the OSI stack, placedbetween Layer 3 (Network) and Layer 2 (Data Link), usually named the “2.5Layer”.The term multiprotocol derives from the fact that MPLS is able to manage anylayer 3 protocol and, typically, is applied to the IP protocols.How does it work?As shown in figure 2.2, a router operating in an MPLS domain is called LabelSwitching Router (LSR) and the one receiving/transmitting traffic from/to outsidethe domain is called Edge LSR (ELSR) or Label Edge Router (LER).The main concept driving the MPLS idea is that packets arriving at the ingressLER have to be transported inside the MPLS domain, toward the egress LER.For each destination address, or for each LER, a Forward Equivalent Class(FEC) is defined that aggregates packets needing the same treatment and directedto the same destination.When an LER receives an IP packet, it classifies such packet in the correspondentFEC, basing on the information contained in the IP header. Moreover, it insertsa Label between the layer 2 header (e.g. Ethernet or ATM) and the layer 3 header(e.g. IP).Labels are assigned and distributed by means of a protocol used for this8
Page 4 and 5: AcknowledgementsThis dissertation w
Page 6 and 7: AbstractThis dissertation investiga
Page 9 and 10: CONTENTS7.4 The Real ISP’s Italia
Page 11 and 12: LIST OF FIGURES7.3 Default metrics
Page 13 and 14: 1.2 Objectives of the dissertation2
Page 15 and 16: Chapter 2Basic knowledgeThis chapte
Page 17: 2.1 Understanding IS-IS• A = sour
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Page 23 and 24: 2.4 Restoration SchemesHowever, fai
Page 26 and 27: 3.1 Optimization of IS-IS/OSPF rout
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Page 31 and 32: 4.1 Heuristic Algorithmsmeta-heuris
Page 33 and 34: 4.1 Heuristic Algorithmsto keep a c
Page 35 and 36: 4.1 Heuristic Algorithmsprobability
Page 37 and 38: 4.3 Linear Programming ApproachExam
Page 39 and 40: 5.2 Traffic monitoring• 60% of th
Page 41 and 42: 5.2 Traffic monitoringExporting the
Page 43 and 44: 5.2 Traffic monitoringare included
Page 45 and 46: 5.2 Traffic monitoringthe Internet.
Page 47 and 48: 5.2 Traffic monitoring5.2.3 The net
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Page 51 and 52: 5.2 Traffic monitoringFigure 5.9: S
Page 53 and 54: Chapter 6LP Optimization ModelsThis
Page 55 and 56: 6.2 Graphs and Network Flowswith a
Page 57 and 58: 6.2 Graphs and Network FlowsWhere B
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Page 61 and 62: 6.3 Multicommodity Flow Problemscom
Page 63 and 64: 6.4 LP modelsThe second layer intro
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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6.4 LP models(a) Rerouting flow p
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6.4 LP models(a) 1 st solution(b) 2
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6.4 LP models∑f∈Fx f,lij⎛⎝i
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6.4 LP modelsterm is the MPLS part
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7.2 The highly meshed network7.2 Th
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7.3 The IBCN European network7.3 Th
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7.3 The IBCN European networkmaximu
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7.3 The IBCN European networkSurviv
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7.3 The IBCN European networkFigure
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7.4 The Real ISP’s Italian Backbo
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7.5 Conclusion and validation of re
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optimal configuration of network pa
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REFERENCES[14] Jones Lustig Format
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REFERENCES[40] A. V. Fiacco and G.
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REFERENCES[61] A. Nucci, B. Schroed
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Davide Cherubini - PhD Thesis - UniCA Eprints

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