Made available in DSpace on 2014-06-12T15:59:17Z (GMT). No. of bitstreams: 2 arquivo4992_1.pdf: 465621 bytes, checksum: beb55c17d095bd73e42ae404d38057fa (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2002 / A crescente demanda e o explosivo crescimento da Internet está impondo novos desafios para a garantia de serviços em termos de performance, confiabilidade e Qualidade de Serviço (QoS). Muitas aplicações de missão crítica que dependem das tecnologias de rede não podem funcionar sem garantias expressas de entrega. Entretanto, as redes de dados atuais não oferecem nenhuma garantia de que as exigências feitas a nível de serviço possam ser garantidas sem algum tipo de degradação a qualquer hora, do dia ou da noite, a despeito de outros usuários da rede. Para atender essas exigências, a infra-estrutura da rede precisa ser melhorada com novas tecnologias que ofereçam aos operadores de rede ferramentas para controlar o comportamento da mesma. Juntas, as capacidades oferecidas pela Engenharia de Tráfego, pelo MPLS (Multiprotocol Label Switching) e pelo DiffServ possibilitam o controle e o balanceamento de carga na rede necessários à entrega de serviço de acordo com contratos personalizados. Este trabalho apresenta o MPLS associado à Engenharia de Tráfego como solução para o problema de alocação ineficiente dos recursos em uma rede e o conseqüente congestionamento provocado por tal problema. O esquema de encaminhamento de pacotes do MPLS é empregado como estratégia para minimizar o congestionamento ou alternativamente maximizar a utilização dos recursos, através da alocação eficiente dos mesmos, garantindo, num ambiente com diferenciação de serviço, uma melhor Qualidade de Serviço em termos de redução na perda de pacotes, no atraso e na variação de atraso, e no aumento da vazão agregada

Many reports have been written about the techniques behind Virtual Private Networks (VPN) and Multi Protocol Label Switching (MPLS). They usually deal with the low level design of the software implementing a specific technique. The initial products are usually not mature enough to run in a large network or have to be adjusted in some way to fit. This report investigates the different ways of implementing strict layer 2 Virtual Private Networks in an existing nation-wide Gigabit Ethernet. The infrastructure in use, as well as the hardware, has to be used without major changes. Since 1998/1999, when MPLS first started in the laboratories, development has continued. Today it is possible to introduce MPLS or tunneled national virtual local area network into an existing network. This requires high speed, fault tolerant, and stable hardware and software. Going beyond the separation of traffic at layer 3 using Virtual Private Networks, i.e., IPSec, we can tunnel layer 2 traffic through a network. Although the first layer 3 VPN products are already in use, layer 2 VPNs still need to be evaluated and brought into regular use. There are currently two ways of tunneling VLANs in a core network: tunneled VLANs (or as Extreme Networks calls them, VMANs) and MPLS. This project showed that it is possible to start with a VLAN-only solution, and then upgrade to MPLS to solve scalability issues. The VMAN solution can not be used at Arrowhead, since there are too many disadvantages in the way Extreme Networks has implemented it. However, a mix of tunneling VMAN in a VLAN core is possible, and enables customer tagging of VLANs in a Layer 2 VPN. Furthermore, the testing of EAPS and per-VLAN Spanning Tree Protocol turned out well, and showed that EAPS should not be used when there is more than one loop.

Multiprotocol Label Switching (MPLS) fuses the intelligence of routing with the performance of switching and provides significant benefits to networks with a pure IP architecture as well as those with IP and ATM or a mix of ther Layer 2 technologies. MPLS technology is key to scalable virtual private networks (VPNs) and end-to-end quality of service (QoS), enabling efficient utilization of existing networks to meet future growth. The technology also helps to deliver highly scalable, differentiated end-to-end IP services with simpler configuration, management, and provisioning for both Internet providers and end-users. However, MPLS is a connection-oriented architecture. In case of failure MPLS first has to establish a new label switched path (LSP) and then forward the packets to the newly established LSP. For this reason MPLS has a slow restoration response to a link or node failure on the LSP.The thesis provides a description of MPLS-based architecture as a preferred technology for integrating ATM and IP technologies, followed by a discussion of the motivation for the fast and reliable restoration mechanism in an MPLS network. In this thesis first we address the fast rerouting mechanisms for MPLS networks and then we focus on the problem of packet loss, packet reordering and packet delay for protected LSP in MPLS-based network for a single node/link failure. In order to deliver true service assurance for guaranteed traffic on a protected LSP we use the fast rerouting mechanism with a preplanned alternative LSP. We propose enhancements to current proposals described in extant literature. Our fast rerouting mechanism avoids packet disorder and significantly reduces packet delay during the restoration period.An extension of the Fast Rerouting proposal, called Reliable and Fast Rerouting (RFR), provides some preventive actions for the protected LSP against packet loss during a failure. RFR maintains the same advantages of Fast Rerouting while eliminating packet losses, including those packet losses due to link or node failure (circulating on the failed links), which were considered to be "inevitable" up to now.For the purpose of validating and evaluating the behavior of these proposals a simulation tool was developed. It is based on the NS, a well-known network simulator that is being used extensively in research work. An extension featuring the basic functionality of MPLS (MNS) is also available for the NS, and this is the basis of the developed simulation tool.Simulation results allow the comparison of Fast Rerouting and RFR with previous rerouting proposals.In addition to this we propose a mechanism for multiple failure recovery in an LSP. This proposal combines the path protection, segment protection and local repair methods. In addition to the multiple link/node failure protection, the multiple fault tolerance proposal provides a significant reduction of delay that the rerouted traffic can experience after a link failure, because the repair action is taken close to the point of failure.Then we proceed to address an inherent problem of the preplanned alternative LSP. As alternative LSPs are established together with the protected LSP it may happen that the alternative is not the optimal LSP at the time the failure occurs. To overcome this undesired behavior, we propose the Optimal and Guaranteed Alternative Path (OGAP). The proposal uses a hybrid of fast-rerouting and a dynamic approach to establish the optimal alternative LSP while rerouting the affected traffic using the preplanned alternative LSP. This hybrid approach provides the best of the fast rerouting and the dynamic approaches.At the same time we observed that the protection path becomes in fact unprotected from additional failures after the traffic is rerouted onto it.To address this we propose a guarantee mechanism for protection of the new protected LSP carrying the affected traffic, by establishing an alternative LSP for the rerouted traffic after a failure, avoiding the vulnerability problem for the protected traffic.Finally, we present a further optimization mechanism, adaptive LSP, to enhance the existing traffic engineering for Quality of Services (QoS)provision and improve network resource utilization. The adaptive LSP proposal allows more flexibility in network resource allocation and utilization by adapting the LSP to variations in all network loads,resulting in an enhancement of existing MPLS traffic engineering.

Made available in DSpace on 2016-04-04T18:31:31Z (GMT). No. of bitstreams: 1 Ana Cristina Pereira de P Assolari.pdf: 1062992 bytes, checksum: 86b8f894fb835cd2496911a4689155b6 (MD5) Previous issue date: 2011-02-11 / IT and Telecommunication Managers need to be on top of rnarket trends so they rnay proceed to necessary changes and improvement on their network in order to keep up with business challenges and ensure the future of the cornpany, The decision making related to network migration should not be rnade without a consistent and reliable method that would support the decision taken, protecting the managers and companies from risks and losses. This paper has the objective to propose the usage of multicriteria decision making methodology, with focus on the MACBETH method in arder to support the network migration, based on information extracted from the financiai reports published on the public internet. This paper will show the study of two companies that have m igrated to MPLS in the last five years, buildlng the MACBETH Model from information present on the Financiai Report at the time of contract was signed and validating the information extracted with executives from the commercial and technical departments who lived through that period in the company. Within this scenario it can be verified that MACBETH Method once provided with the correct information that reflects the period the cornpany is living rnay help executives to decide if they should migrate ar not migrate their network / Gestores de telecomunica??es e TI precisam estar sempre atentos aos rumos da organiza??o e com isso procederem a mudan?as necess?rias nas estruturas e redes de comunica??o que subsidiam os neg?cios da empresa. A tomada de decis?o a respeito da migra??o de tecnologias n?o dever ser efetuada sem um m?todo consistente que as subsidie, livrando o gestor de riscos e preju?zos empresariais que podem ser minjmizados quando uma abordagem estruturada elencando os principais crit?rios a serem considerados ? utilizada. Este trabalho tem como objetivo propor o uso de metodologia para tomada de decis?o multicrit?rio, com foco no m?todo MACBETH, para subsidiar a migra??o de plataformas de redes de telecomunica??es. Com base em informa??es oriundas de boletins financeiros disponibilizados publicamente na Internet. O trabalho analisa duas empresas que migraram para plataforma MPLS, construindo a estrutura do m?todo MACBETH a partir das informa??es obtidas nos boletins financeiros dessas organiza??es e validando a an?lise com dados obtidos de gerentes das ?reas comerciais e de tecnologias que vivenciaram esse per?odo. Dentro desse quadro, considerou-se que o m?todo MACBETH, uma vez alimentado com informa??es corretas que reflitam o momento da empresa, pode orientar gestores a decidirem se devem ou n?o proceder ? migra??o de suas bases tecnol?gicas