Thesis (MSc)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Multiprotocol Label Switching (MPLS) is a routing technology which can manage Quality of Service (QoS) in scalable connectionless networks using relatively simple packet forwarding mechanisms. This thesis considers the optimisation of the QoS offered by an MPLS network. The QoS measure used is the expected packet delay which is minimised by switching packets along optimal label switched paths (LSPs). Two mathematical models of MPLS networks are presented together with appropriate algorithms for optimally dividing the network traffic into forwarding equivalence classes (FECs), finding optimal LSPs which minimise the expected packet delay and switching these FECs along the optimal LSPs. These algorithms are applied to compute optimal LSPs for several test networks. The mathematics on which these algorithms are based is also reviewed. This thesis provides the MPLS network operator with efficient packet routing algorithms for optimising the network's QoS. / AFRIKAANSE OPSOMMING: Multiprotocol Label Switching (MPLS) is 'n roeteringsmetode om die diensvlak (QoS) van 'n skaleerbare, verbindinglose netwerk te bestuur deur middel van relatief eenvoudige versendingsmeganismes. Hierdie tesis beskou die optimering van die QoS van 'n MPLS-netwerk. Die QoS-maatstaf is die verwagte vert raging van 'n netwerk-pakkie. Dit word geminimeer deur pakkies langs optimale "label switched paths" (LSPs) te stuur. Twee wiskundige modelle van MPLS-netwerke word ondersoek. Toepaslike algoritmes word verskaf vir die optimale verdeling van die netwerkverkeer in "forwarding equivalence classes" (FECs), die soektog na optimale LSPs (wat die verwagte pakkie-vertraging minimeer) en die stuur van die FECs langs die optimale LSPs. Hierdie algoritmes word ingespan om optimale LSPs vir verskeie toetsnetwerke op te stel. Die wiskundige teorie waarop hierdie algoritmes gegrond is, word ook hersien. Hierdie tesis verskaf doeltreffende roeteringsalgoritmes waarmee 'n MPLS-netwerkbestuurderj-es die netwerk se QoS kan optimeer.

Bibliography: leaves 128-135. Investigates the behaviour of TCP bulk file transfer application sessions in a broadband access environment. Introduces some concepts for evaluating network behaviour: a path instability parameter for analyzing different TCP connections; a minimum RTT delay and a minimum typical path for estimating path characteristics between a client and application servers.

Thesis (MSc) -- Stellenbosch University, 2004. / ENGLISH ABSTRACT: The Internet is fast evolving into a commercial platform that carries a mixture of narrow- and broadband applications such as voice, video, and data. Users expect a certain level of guaranteed service from their service providers and consequently the need exists for efficient Internet traffic engineering to enable better Quality of Service (QoS) capabilities. Multi-protocol Label Switching (MPLS) is a label switching protocol that has emerged as an enabling technology to achieve efficient traffic engineering for QoS management in IP networks. The ability of the MPLS protocol to create explicit virtual connections called Label Switched Paths (LSPs) to carry network traffic significantly enhances the traffic engineering capabilities of communication networks. The MPLS protocol supports two options for explicit LSP selection: offline LSP computation using an optimization method and dynamic route selection where a single node makes use of current available network state information in order to compute an explicit LSP online. This thesis investigates various methods for the selection of explicit bandwidth guaranteed LSPs through dynamic route selection. We address the problem of computing a sequence of optimal LSPs where each LSP can carry a specific traffic demand and we assume that no prior information regarding the future traffic demands are available and that the arrival sequence of LSP requests to the network is unknown. Furthermore, we investigate the rerouting abilities of the online LSP selection methods to perform MPLS failure restoration upon link failure. We propose a new online routing framework known as Least Interference Optimization (LIO) that utilizes the current bandwidth availability and traffic flow distribution to achieve efficient traffic engineering. We present the Least Interference Optimization Algorithm (LIOA) that reduces the interference among competing network flows by balancing the number and quantity of flows carried by a link for the setup of bandwidth guaranteed LSPs in MPLS networks. The LIOA routing strategy is evaluated and compared against well-known routing strategies such as the Minimum Hop Algorithm (MHA), Minimum Interference Routing Algorithm (MIRA), Open Shortest Path First (OSPF) and Constraint Shortest Path First (CSPF) by means of simulation. Simulation results revealed that, for the network topologies under consideration, the routing strategies that employed dynamic network state information in their routing decisions (LIOA, CSPF and MIRA) generally outperformed the routing strategies that only rely on static network information (OSPF and MHA). In most simulation experiments the best performance was achieved by the LIOA routing strategy while the MHA performed the worse. Furthermore we observed that the computational complexity of the MIRA routing strategy does not translate into equivalent performance gains. We employed the online routing strategies for MPLS failure recovery upon link failure. In particular we investigated two aspects to determine the efficiency of the routing strategies for MPLS rerouting: the suitability of the LSP configuration that results due to the establishment of LSPs prior to link failure and the ability of the online routing strategy to reroute failed LSPs upon link failure. Simulation results revealed similar rerouting performance for all online routing strategies under investigation, but a LSP configuration most suitable for online rerouting was observed for the LIOA routing strategy. / AFRIKAANSE OPSOMMING:Die Internet is voordurend besig om te evoleer in 'n medium wat 'n wye reeks moderne kommunikasietegnologiee ondersteun, insluitende telefoon, video en data. Internet gebruikers verwag gewaarborgde diens van hul diensverskaffers en daar bestaan dus 'n vraag na doeltreffende televerkeerbeheer vir gewaarborgde Internet diensgehalte. Multiprotokol Etiketskakeling (MPLS) is 'n etiketskakeling protokol wat doeltreffende televerkeerbeheer en diensgehalte moontlik maak deur die eksplisiete seleksie van virtuele konneksies vir die transmissie van netwerkverkeer in Internetprotokol (IP) netwerke. Hierdie virtuele konneksies staan bekend as etiketgeskakelde paaie. Die MPLS protokol ondersteun tans twee moontlikhede vir eksplisiete seleksie van etiketgeskakelde paaie: aflyn padberekening met behulp van optimeringsmetodes en dinamiese aanlyn padseleksie waar 'n gekose node 'n eksplisiete pad bereken deur die huidige stand van die netwerk in ag te neem. In hierdie tesis word verskeie padseleksiemetodes vir die seleksie van eksplisiete bandwydte-gewaarborgde etiketgeskakelde paaie deur mid del van dinamiese padseleksie ondersoek. Die probleem om 'n reeks optimale etiketgeskakelde paaie te bereken wat elk 'n gespesifeerde verkeersaanvraag kan akkommodeer word aangespreek. Daar word aanvaar dat geen informasie in verband met die toekomstige verkeersaanvraag bekend is nie en dat die aankomsvolgorde van etiketgeskakelde pad verso eke onbekend is. Ons ondersoek verder die herroeteringsmoontlikhede van die aanlyn padseleksiemetodes vir MPLS foutrestorasie in die geval van skakelonderbreking. Vir hierdie doel word 'n nuwe aanlyn roeteringsraamwerk naamlik Laagste Inwerking Optimering (LIO) voorgestel. LIO benut die huidige beskikbare bandwydte en verkeersvloeidistribusie van die netwerk om doeltreffende televerkeerbeheer moontlik te maak. Ons beskryf 'n Laagste Inwerking Optimering Algoritme (LIOA) wat die inwerking tussen kompeterende verkeersvloei verminder deur 'n balans te handhaaf tussen die aantal en kwantiteit van die verkeersvloeistrome wat gedra word deur elke netwerkskakel. Die LIOA roeteringstrategie word geevalueer met behulp van simulasie en die resultate word vergelyk met ander bekende roeteringstrategiee insluitende die Minimum Node Algorithme (MHA), die Minimum Inwerking Algoritme (MIRA), die Wydste Kortste Pad Eerste Algoritme (OSPF) en die Beperkte Kortste Pad Eerste Algoritme (CSPF). Die resultate van die simulasie-eksperimente to on dat, vir die netwerk topologiee onder eksperimentasie, die roeteringstratgiee wat roeteringsbesluite op dinamiese netwerk informasie baseer (LIOA, MIRA, CSPF) oor die algemeen beter vaar as die wat slegs staatmaak op statiese netwerkinformasie (MHA, OSPF). In die meeste simulasie-eksperimente vaar die LIOA roeteringstrategie die beste en die MHA roeteringstrategie die slegste. Daar word verder waargeneem dat die komputasiekomplesiteit van die MIRA roeteringstrategie nie noodwendig weerspieel word in die sukses van roeteringsuitkoms nie. In die geval waar die aanlyn roeteringstrategiee aangewend word vir MPLS foutrestorasie, toon die resultate van simulasie-eksperimente dat al die roeteringstrategiee min of meer dieselfde uitkoms lewer ten opsigte van herroetering van onderbreekte verkeersvloei. Die konfigurasie van etiketgeskakelde paaie deur die LIOA roeteringstrategie voor skakelonderbreking is egter die geskikste vir televerkeer herroetering na skakelonderbreking

The growth of Asynchronous Transfer Mode (ATM) was considered to be the ideal carrier of the high bandwidth applications like video on demand and multimedia e-learning. ATM emerged commercially in the beginning of the 1990's. It was designed to provide a different quality of service at a speed up 100 Gbps for both real time and non real time application. The turn of the 90's saw a variety of technologies being developed. This project analyzes these technologies, compares them to the Asynchronous Transfer Mode and assesses the future of ATM.