Metro Area Network Single Link Failure- Fast Spanning Tree Reconnection

Due to Affordability, ease of maintenance and ubiquity, Ethernet has become a preferred technology to be deployed in to LAN, MAN and WAN networks. Even though Ethernet has being used widely for switched communication it is not meet requirement for Metro Area Networks in terms of network resilience. In this paper, author propose the fast spanning tree re-connection formula, especially for Metro Area Ethernet networks to manage any single link failure, and it has most important feature of fast recovery, backup capacity grantees and ease of fast recovery. If in case of link failure on a spanning tree, a distributed failure recovery protocol is activated to rebuild the broken spanning tree. This is re-connecting the link but not a spanning tree. Author presents the details of the protocol, which including failure notification and forwarding table reconfiguration manual. The Integer linear programming (ILP) is formulated to reconnect-links as it pre-configured. The result of optimization gives the remark of lower implementation cost, fast and effective spanning tree reconnection mechanism can achieve better performance than other resilient technique for Metro Ethernet Network

Engenharia de tráfego de redes ethernet baseadas em árvores de suporte

Mestrado em Engenharia Electrónica e TelecomunicaçõesDado o seu custo, a tecnologia Ethernet tem vindo progressivamente a ser utilizada nas redes dos operadores públicos, nos seus segmentos de rede de acesso e rede metropolitana. Tradicionalmente, o encaminhamento em redes Ethernet é baseado numa única árvore de suporte. Esta forma de funcionamento, apropriada para redes de área local (LANs), não responde aos requisitos de uma rede de operador. Num passado recente, a Ethernet tornou-se mais atractiva como tecnologia para um operador com a introdução dos protocolos IEEE 802.1w Rapid Spanning Tree Protocol (RSTP), que permite tempos de reconfiguração da árvore de suporte de menos de um segundo quando há falhas de rede, e IEEE 802.1s Multiple Spanning Tree Protocol (MSTP), que permite balancear o tráfego pelas diferentes ligações de rede com base em múltiplas árvores de suporte, conseguindo-se, assim, uma melhor utilização dos recursos da rede. Este trabalho aborda primeiro a evolução dos protocolos de encaminhamento para redes de camada 2 baseadas na Ethernet até à proposta do MSTP. Depois, faz um estudo da literatura científica do modo como o MSTP tem sido explorado para melhorar os diferentes aspectos do funcionamento de uma rede de telecomunicações tais como o balanceamento de carga, optimização da utilização da rede, qualidade de serviço, etc.Due to its cost, Ethernet technology is being progressively used on the access and metropolitan segments of public operator networks. Traditionally, routing on Ethernet networks was based on a single spanning tree. This paradigm, which is appropriate for LAN environments, does not answer to the requirements of a public operator network. Recently, Ethernet became more attractive to operators with the introduction of two new protocols: IEEE 802.1w Rapid Spanning Tree Protocol (RSTP), enabling spanning tree reconfigurations below 1 second, and IEEE 802.1s Multiple Spanning Tree Protocol (MSTP), enabling a better load balance among all network links based on multiple spanning trees and, thus, improving the network resource utilization. This work addresses, firstly, the evolution of layer 2 routing protocols up to MSTP used in Ethernet networks. Then, it makes a comprehensive scientific state-of-art on the different ways that MSTP has been proposed in order to improve different aspects of telecommunication networks like load balancing, optimization of network utilization, quality of service, etc

Survivability schemes for metro ethernet networks

Ph.DDOCTOR OF PHILOSOPH

Optimal Design Strategies for Survivable Carrier Ethernet Networks

Ethernet technologies have evolved through enormous standardization efforts over the past two decades to achieve carrier-grade functionalities, leading to carrier Ethernet. Carrier Ethernet is expected to dominate next generation backbone networks due to its low-cost and simplicity. Ethernet's ability to provide carrier-grade Layer-2 protection switching with SONET/SDH-like fast restoration time is achieved by a new protection switching protocol, Ethernet Ring Protection (ERP). In this thesis, we address two important design aspects of carrier Ethernet networks, namely, survivable design of ERP-based Ethernet transport networks together with energy efficient network design. For the former, we address the problem of optimal resource allocation while designing logical ERP for deployment and model the combinatorially complex problem of joint Ring Protection Link (RPL) placements and ring hierarchies selection as an optimization problem. We develop several Mixed Integer Linear Programming (MILP) model to solve the problem optimally considering both single link failure and concurrent dual link failure scenarios. We also present a traffic engineering based ERP design approach and develop corresponding MILP design models for configuring either single or multiple logical ERP instances over one underlying physical ring. For the latter, we propose two novel architectures of energy efficient Ethernet switches using passive optical correlators for optical bypassing as well as using energy efficient Ethernet (EEE) ports for traffic aggregation and forwarding. We develop an optimal frame scheduling model for EEE ports to ensure minimal energy consumption by using packet coalescing and efficient scheduling

FatPaths: Routing in Supercomputers and Data Centers when Shortest Paths Fall Short

We introduce FatPaths: a simple, generic, and robust routing architecture that enables state-of-the-art low-diameter topologies such as Slim Fly to achieve unprecedented performance. FatPaths targets Ethernet stacks in both HPC supercomputers as well as cloud data centers and clusters. FatPaths exposes and exploits the rich ("fat") diversity of both minimal and non-minimal paths for high-performance multi-pathing. Moreover, FatPaths uses a redesigned "purified" transport layer that removes virtually all TCP performance issues (e.g., the slow start), and incorporates flowlet switching, a technique used to prevent packet reordering in TCP networks, to enable very simple and effective load balancing. Our design enables recent low-diameter topologies to outperform powerful Clos designs, achieving 15% higher net throughput at 2x lower latency for comparable cost. FatPaths will significantly accelerate Ethernet clusters that form more than 50% of the Top500 list and it may become a standard routing scheme for modern topologies

A study of the applicability of software-defined networking in industrial networks

173 p.Las redes industriales interconectan sensores y actuadores para llevar a cabo funciones de monitorización, control y protección en diferentes entornos, tales como sistemas de transporte o sistemas de automatización industrial. Estos sistemas ciberfísicos generalmente están soportados por múltiples redes de datos, ya sean cableadas o inalámbricas, a las cuales demandan nuevas prestaciones, de forma que el control y gestión de tales redes deben estar acoplados a las condiciones del propio sistema industrial. De este modo, aparecen requisitos relacionados con la flexibilidad, mantenibilidad y adaptabilidad, al mismo tiempo que las restricciones de calidad de servicio no se vean afectadas. Sin embargo, las estrategias de control de red tradicionales generalmente no se adaptan eficientemente a entornos cada vez más dinámicos y heterogéneos.Tras definir un conjunto de requerimientos de red y analizar las limitaciones de las soluciones actuales, se deduce que un control provisto independientemente de los propios dispositivos de red añadiría flexibilidad a dichas redes. Por consiguiente, la presente tesis explora la aplicabilidad de las redes definidas por software (Software-Defined Networking, SDN) en sistemas de automatización industrial. Para llevar a cabo este enfoque, se ha tomado como caso de estudio las redes de automatización basadas en el estándar IEC 61850, el cual es ampliamente usado en el diseño de las redes de comunicaciones en sistemas de distribución de energía, tales como las subestaciones eléctricas. El estándar IEC 61850 define diferentes servicios y protocolos con altos requisitos en terminos de latencia y disponibilidad de la red, los cuales han de ser satisfechos mediante técnicas de ingeniería de tráfico. Como resultado, aprovechando la flexibilidad y programabilidad ofrecidas por las redes definidas por software, en esta tesis se propone una arquitectura de control basada en el protocolo OpenFlow que, incluyendo tecnologías de gestión y monitorización de red, permite establecer políticas de tráfico acorde a su prioridad y al estado de la red.Además, las subestaciones eléctricas son un ejemplo representativo de infraestructura crítica, que son aquellas en las que un fallo puede resultar en graves pérdidas económicas, daños físicos y materiales. De esta forma, tales sistemas deben ser extremadamente seguros y robustos, por lo que es conveniente la implementación de topologías redundantes que ofrezcan un tiempo de reacción ante fallos mínimo. Con tal objetivo, el estándar IEC 62439-3 define los protocolos Parallel Redundancy Protocol (PRP) y High-availability Seamless Redundancy (HSR), los cuales garantizan un tiempo de recuperación nulo en caso de fallo mediante la redundancia activa de datos en redes Ethernet. Sin embargo, la gestión de redes basadas en PRP y HSR es estática e inflexible, lo que, añadido a la reducción de ancho de banda debida la duplicación de datos, hace difícil un control eficiente de los recursos disponibles. En dicho sentido, esta tesis propone control de la redundancia basado en el paradigma SDN para un aprovechamiento eficiente de topologías malladas, al mismo tiempo que se garantiza la disponibilidad de las aplicaciones de control y monitorización. En particular, se discute cómo el protocolo OpenFlow permite a un controlador externo configurar múltiples caminos redundantes entre dispositivos con varias interfaces de red, así como en entornos inalámbricos. De esta forma, los servicios críticos pueden protegerse en situaciones de interferencia y movilidad.La evaluación de la idoneidad de las soluciones propuestas ha sido llevada a cabo, principalmente, mediante la emulación de diferentes topologías y tipos de tráfico. Igualmente, se ha estudiado analítica y experimentalmente cómo afecta a la latencia el poder reducir el número de saltos en las comunicaciones con respecto al uso de un árbol de expansión, así como balancear la carga en una red de nivel 2. Además, se ha realizado un análisis de la mejora de la eficiencia en el uso de los recursos de red y la robustez alcanzada con la combinación de los protocolos PRP y HSR con un control llevado a cabo mediante OpenFlow. Estos resultados muestran que el modelo SDN podría mejorar significativamente las prestaciones de una red industrial de misión crítica

Security in the software defined networking infrastructure

Software Defined Networks (SDN) is a paradigm in which control and data planes of traditional networking devices are decoupled to form a distrubuted model. Communication between the separate planes requires a protocol such as OpenFlow to leverage programmable routing and forwarding decisions on the network. In this model, Application Programmable Interfaces (APIs) make it possible to inject policy and forwarding rules via the control plane or controller. The most prominent challenges resulting from the separation is link security between the separated elements through which private network data is now traversing. One main area of concern is the method of transmission with which the majority of Open-Source controllers currently communicate. The preferred practice is for a Transport Layer Security (TLS) channel initiation by an OpenFlow switch wishing to communicate with a controller. Many developers have replaced the TLS method of communication with straight Transport Control Protocol (TCP) due to handshake sequence issues caused by certificate exchange during the TLS connection phase. This thesis and the subsequent research will ask questions on security around the controller to device links that pass flow tables , network abstractions and multi-layer information to multiple controlled network elements. The main objective of this research is to develop testing procedures that allow for accurate and repeatable experiments. Therefore, in researching security vulnerabilities between controllers and forwarding devices, benchmarking performed on secure links tests the capability of authentication mechanisms to function properly under load. The outcomes of this research include a series of quality industry standard tests to benchmark typical SDN controllers and forwarding devices. A critical analysis of typical devices at low, medium and high loads. An SDN security taxonomy is presented to help with future categorising of device testing in context of SDN architecture