Ethernet - a survey on its fields of application

During the last decades, Ethernet progressively became the most widely used local area networking (LAN) technology. Apart from LAN installations, Ethernet became also attractive for many other fields of application, ranging from industry to avionics, telecommunication, and multimedia. The expanded application of this technology is mainly due to its significant assets like reduced cost, backward-compatibility, flexibility, and expandability. However, this new trend raises some problems concerning the services of the protocol and the requirements for each application. Therefore, specific adaptations prove essential to integrate this communication technology in each field of application. Our primary objective is to show how Ethernet has been enhanced to comply with the specific requirements of several application fields, particularly in transport, embedded and multimedia contexts. The paper first describes the common Ethernet LAN technology and highlights its main features. It reviews the most important specific Ethernet versions with respect to each application field’s requirements. Finally, we compare these different fields of application and we particularly focus on the fundamental concepts and the quality of service capabilities of each proposal

Plano de Controle GMPLS para Redes Ópticas de Transporte

Neste trabalho é apresentada a proposta de estudo do plano de controle de redes ópticas de transporte, OTN, e sua automação a partir dos padrões e protocolos propostos pelos principais órgãos de padronização na área de telecomunicações e redes de dados: a ITU-T, que define uma arquitetura para redes ópticas automaticamente comutadas (ASON), e o IETF, que propõe uma generalização do MPLS para o controle de redes não-pacotes (GMPLS). O objetivo do trabalho é estudar como esses padrões e protocolos podem ser utilizados para controlar as redes OTN e desenvolver uma proposta de interação entre o plano de controle e a rede óptica, a fim de que seja possível fornecer uma rede de transporte confiável, convergente e focada em serviços

Encaminhamento robusto em redes GMPLS sobre SDH

Mestrado em Engenharia Electrónica e TelecomunicaçõesEsta dissertação endereça o problema do encaminhamento robusto em redes GMPLS (Generalised Multi-Protocol Label Switching) sobre SDH (Synchronous Digital Hierarchy). Actualmente, o encaminhamento das redes SDH é feito de forma centralizada e por gestão. As redes SDH têm requisitos de recuperação a falhas muito exigentes pelo que a robustez da rede é tipicamente implementada por mecanismos de protecção. Os mecanismos mais simples e de melhor desempenho em termos de tempo de recuperação a falhas são os que por cada VC (Virtual Container) de serviço também estabelecem um VC de protecção cujo percurso na rede não inclui nenhum dos comutadores do percurso de serviço (excepto os comutadores extremo). Estes mecanismos garantem a robustez completa da rede no caso de falha de um único elemento quer seja um comutador ou uma ligação. A motivação para acrescentar a camada protocolar GMPLS às redes SDH é a de dotar estas redes com a capacidade do estabelecimento de VCs por sinalização e de permitir que o encaminhamento seja implementado o mais possível de uma forma distribuída diminuindo assim a sua dependência de um sistema centralizado de gestão. Os protocolos de encaminhamento GMPLS baseiam-se na atribuição de um custo a cada ligação de rede, fixo ou variável no tempo, e na determinação do encaminhamento pelos percursos cuja soma dos custos das ligações que o compõem é mínima. Nesta dissertação propõese a utilização de um algoritmo de pares de percursos disjuntos de custo mínimo no estabelecimento do par VC de serviço, VC de protecção. Quando existem restrições ao encaminhamento, a determinação do percurso de custo mínimo considera apenas as ligações que cumprem com as restrições. Neste trabalho, propõe-se uma estratégia de atribuição de custos que não só depende da carga da ligação mas também do número e tipo de VCs que a ligação em cada momento suporta. Por simulação, mostra-se que esta estratégia tem melhor desempenho que as estratégias tradicionais de um custo fixo inversamente proporcional à capacidade da ligação ou de um custo que em cada instante é proporcional à carga de cada ligação. Finalmente, propõe-se um esquema centralizado adicional que, sempre que um VC é libertado, recalcula os percursos de todos os VCs de protecção por forma a diminuir a probabilidade de bloqueio global da rede. O objectivo é obter uma melhoria adicional do desempenho não causando nenhuma interrupção de serviço pois, no estado normal da rede, apenas os VCs de serviço suportam efectivamente o tráfego. No âmbito desta dissertação, o desempenho dos diferentes algoritmos de encaminhamento é analisado por simulação pelo que foi desenvolvido um simulador de eventos discretos adequado.This work addresses the problem of survivable routing in SDH (Synchronous Digital Hierarchy) networks with a GMPLS (Generalised Multi-Protocol Label Switching) routing plane. Currently, routing in SDH networks is done in a centralized way by management means. SDH networks have failure recovery exigent requirements so that network survivability is tipically implemented with protection mechanisms. The most simple and efficient mechanisms are the ones that for each service VC (Virtual Container) also establish one protection VC through a path that does not include any of the nodes of the service VC (besides the origin and destination nodes). These mechanisms garanty the network survivability in case of a single node or link failure. The motivation to add the GMPLS control plane on SDH networks is to enable these networks to establish VCs by signalling and to allow as far as possible routing in a distributed way reducing the network dependence on centralized management systems. The GMPLS routing protocols are based on minimum cost routing where either a static or variable cost value is assigned to each network link and the routing paths are given by the minimum cost paths. When there are routing constraints, the determination of the minimal cost paths is applied only to links that observe the constraints. In this work, it is proposed a strategy of cost assignement that depends not only on the link load but also of the number and type of VCs that the link suppports at each time. By simulation, it is shown that this strategy has better performance than the traditional strategies of a static cost inversely proportional to link capacity or of a cost that is proportional to link load at each time. The proposed strategies use a routing algorithm that determines a minimal cost node-disjoint pair of paths in the establishment of the pair service VC and protection VC. Finally, it is proposed an additional centralized scheme that when one VC is released, all protection VCs are recalculated in order to reduce the network overall blocking probability. This scheme allows an additional performance improvement and does not cause any service disruption because in normal operation the service VC’s are the only ones supporting traffic. The performance of all routing algorithms are determined by simulation with a discret event simulator developed for this purpose

End-to-end provisioning in multi-domain/multi-layer networks

The last decade has seen many advances in high-speed networking technologies. At the Layer 1 fiber-optic level, dense wavelength division multiplexing (DWDM) has seen fast growth in long-haul backbone/metro sectors. At the Layer 1.5 level, revamped next-generation SONET/SDH (NGS) has gained strong traction in the metro space, as a highly flexible sub-rate\u27 aggregation and grooming solution. Meanwhile, ubiquitous Ethernet (Layer 2) and IP (Layer 3) technologies have also seen the introduction of new quality of service (QoS) paradigms via the differentiated services (Diff-Serv) and integrated services (Intserv) frameworks. In recent years, various control provisioning standards have also been developed to provision these new networks, e.g., via efforts within the IETF, ITU-T, and OIF organizations. As these networks technologies gain traction, there is an increasing need to internetwork multiple domains operating at different technology layers, e.g., IP, Ethernet, SONET, DWDM. However, most existing studies have only looked at single domain networks or multiple domains operating at the same technology layer. As a result, there is now a growing level of interest in developing expanded control solutions for multi-domain/multi-layer networks, i.e., IP-SONET-DWDM. Now given the increase in the number of inter-connected domains, it is difficult for a single entity to maintain complete \u27global\u27 information across all domains. Hence, related solutions must pursue a distributed approach to handling multi-domain/multi-layer problem. Namely, key provisions are needed in the area of inter- domain routing, path computation, and signaling. The work in this thesis addresses these very challenges. Namely, a hierarchical routing framework is first developed to incorporate the multiple link types/granularities encountered in different network domains. Commensurate topology abstraction algorithms and update strategies are then introduced to help condense domain level state and propagate global views. Finally, distributed path computation and signaling setup schemes are developed to leverage the condensed global state information and make intelligent connection routing decisions. The work leverages heavily from graph theory concepts and also addresses the inherent distributed grooming dimension of multi-layer networks. The performance of the proposed framework and algorithms is studied using discrete event simulation techniques. Specifically, a range of multi-domain/multi-layer network topologies are designed and tested. Findings show that the propagation of inter-domain tunneled link state has a huge impact on connection blocking performance, lowering inter-domain connection blocking rates by a notable amount. More importantly, these gains are achieved without any notable increase in inter-domain routing loads. Furthermore, the results also show that topology abstraction is most beneficial at lower network load settings, and when used in conjunction with load-balancing routing.\u2