A Survey on the Contributions of Software-Defined Networking to Traffic Engineering

Since the appearance of OpenFlow back in 2008, software-defined networking (SDN) has gained momentum. Although there are some discrepancies between the standards developing organizations working with SDN about what SDN is and how it is defined, they all outline traffic engineering (TE) as a key application. One of the most common objectives of TE is the congestion minimization, where techniques such as traffic splitting among multiple paths or advanced reservation systems are used. In such a scenario, this manuscript surveys the role of a comprehensive list of SDN protocols in TE solutions, in order to assess how these protocols can benefit TE. The SDN protocols have been categorized using the SDN architecture proposed by the open networking foundation, which differentiates among data-controller plane interfaces, application-controller plane interfaces, and management interfaces, in order to state how the interface type in which they operate influences TE. In addition, the impact of the SDN protocols on TE has been evaluated by comparing them with the path computation element (PCE)-based architecture. The PCE-based architecture has been selected to measure the impact of SDN on TE because it is the most novel TE architecture until the date, and because it already defines a set of metrics to measure the performance of TE solutions. We conclude that using the three types of interfaces simultaneously will result in more powerful and enhanced TE solutions, since they benefit TE in complementary ways.European Commission through the Horizon 2020 Research and Innovation Programme (GN4) under Grant 691567 Spanish Ministry of Economy and Competitiveness under the Secure Deployment of Services Over SDN and NFV-based Networks Project S&NSEC under Grant TEC2013-47960-C4-3-

Resilient communications in smart grids

Tese de mestrado, Segurança Informática, Universidade de Lisboa, Faculdade de Ciências, 2018As redes elétricas, algumas já centenárias, foram concebidas para uma realidade bastante diferente da actual. O facto de terem sido desenhadas para transportar e distribuir a energia de forma unidirecional, torna a infraestrutura rígida, causando problemas em termos de escalabilidade e dificulta a sua evolução. Conhecidas questões ambientais têm levado a que a geração de energia baseada em combustíveis fosseis seja substituída pela geração através de fontes de energia renováveis. Esta situação motivou a criação de incentivos ao investimento nas fontes de energia renováveis, o que levou a que cada vez mais consumidores apostem na microgeração. Estas alterações causaram uma mudança na forma como é feita a produção e distribuição de energia elétrica, com uma aposta crescente na interligação entre as várias fontes ao longo da infraestrutura, tornando a gestão destas redes uma tarefa extremamente complexa. Com o crescimento significativo de consumidores que também podem ser produtores, torna-se essencial uma coordenação cuidada na injeção de energia na rede. Este facto, aliado à crescente utilização de energia elétrica, faz com que a manutenção da estabilidade da rede seja um enorme desafio. As redes inteligentes, ou smart grids, propõem resolver muitos dos problemas que surgiram com esta alteração do paradigma de consumo/produção de energia elétrica. Os componentes da rede passam a comunicar uns com os outros, tornando a rede eléctrica bidirecional, facilitando assim a sua manutenção e gestão. A possibilidade de constante troca de informação entre todos os componentes que constituem a smart grid permite uma reação imediata relativamente às ações dos produtores e consumidores de energia elétrica. No entanto, com esta alteração de paradigma surgiram também muitos desafios. Nomeadamente, a necessidade de comunicação entre os equipamentos existentes nas smart grids leva a que as redes de comunicação tenham de cobrir grandes áreas. Essa complexidade aumenta quando a gestão necessita de ser feita ao nível de cada equipamento e não de forma global. Isto ´e devido ao facto de nas redes de comunicação tradicionais, o plano de controlo e o de dados estarem no mesmo equipamento, o que leva a que o seu controlo seja difícil e propício a erros. Este controlo descentralizado dificulta também a reorganização da rede quando ocorrem faltas pelo facto de não existir um dispositivo que tenha o conhecimento completo da rede. A adaptação rápida a faltas de forma a tornar a comunicação resiliente tem grande importância em redes sensíveis a latência como é o caso da smart grid, pelo que mecanismos eficientes de tolerância a faltas devem ser implementados. As redes definidas por software, ou Software Defined Networks (SDN), surgem como uma potencial solução para estes problemas. Através da separação entre o plano de controlo e o plano de dados, permite a centralização lógica do controlo da rede no controlador. Para tal, é necessário adicionar uma camada de comunicação entre o controlador e os dispositivos de rede, através de um protocolo como o Openflow. Esta separação reduz a complexidade da gestão da rede e a centralização lógica torna possível programar a rede de forma global, de modo a aplicar as políticas pretendidas. Estes fatores tornam a SDN uma soluçãoo interessante para utilizar em smart grids. Esta tese investiga formas de tornar a rede de comunicações empregue numa smart grid resiliente a faltas. Pelas vantagens mencionadas anteriormente, é usada uma solução baseada em SDN, sendo propostos dois módulos essenciais. O primeiro tem como objectivo a monitorização segura da rede, permitindo obter em tempo real métricas como largura de banda, latência e taxa de erro. O segundo módulo trata do roteamento e engenharia de tráfego, utilizando a informação fornecida pelo módulo de monitorização de forma a que os componentes da smart grid comuniquem entre si, garantindo que os requisitos das aplicações são cumpridos. Dada a criticidade da rede elétrica e a importância das comunicações na smart grid, os mecanismos desenvolvidos toleram faltas, quer de tipo malicioso, quer de tipo acidental.The evolution on how electricity is produced and consumed has made the management of power grids an extremely complex task. Today’s centenary power grids were not designed to fit a new reality where consumers can also be producers, or the impressive increase in consumption caused by more sophisticated and powerful appliances. Smart Grids have been prepared as a solution to cope with this problem, by supporting more sophisticated communications among all the components, allowing the grid to react quickly to changes in both consumption or production of energy. On the other hand, resorting to information and communication technologies (ICT) brings some challenges, namely, managing network devices at this scale and assuring that the strict communication requirements are fulfilled is a dauting task. Software Defined Networks (SDN) can address some of these problems by separating the control and data planes, and logically centralizing network control in a controller. The centralised control has the ability to observe the current state of the network from a vantage point, and programatically react based on that view, making the management task substantially easier. In this thesis we provide a solution for a resilient communications network for Smart Grids based on SDN. As Smart Grids are very sensitive to network issues, such as latency and packet loss, it is important to detect and react to any fault in a timely manner. To achieve this we propose and develop two core modules, a network monitor and a routing and traffic engineering module. The first is a solution for monitoring with the goal to obtain a global view of the current state of the network. The solution is secure, allowing malicious attempts to subvert this module to be detected in a timely manner. This information is then used by the second module to make routing decisions. The routing and traffic engineering module ensures that the communications among the smart grid components are possible and fulfils the strict requirements of the Smart Grid

A Comparison of wide area network performance using virtualized and non-virtualized client architectures

The goal of this thesis is to determine if there is a significant performance difference between two network computer architecture models. The study will measure latency and throughput for both client-server and virtualized client architectures. In the client server environment, the client computer performs a significant portion of the work and frequently requires downloading uploading files to and from a remote location. Virtual client architecture turns the client machine into a terminal, sending only keystrokes and mouse clicks and receiving only display pixel or sound changes. I accomplished the goal of comparing these architectures by comparing completion times for ping reply, file download, a small set of common work tasks, and a moderately large SQL database query. I compared these tasks using simulated wide area network, local area network, and virtual client network architectures. The study limits the architecture to one where the virtual client and server are in the same data center

Evaluating and Improving Internet Load Balancing with Large-Scale Latency Measurements

Load balancing is used in the Internet to distribute load across resources at different levels, from global load balancing that distributes client requests across servers at the Internet level to path-level load balancing that balances traffic across load-balanced paths. These load balancing algorithms generally work under certain assumptions on performance similarity. Specifically, global load balancing divides the Internet address space into client aggregations and assumes that clients in the same aggregation have similar performance to the same server; load-balanced paths are generally selected for load balancing as if they have similar performance. However, as performance similarity is typically achieved with similarity in path properties, e.g., topology and hop count, which do not necessarily lead to similar performance, performance between clients in the same aggregation and between load-balanced paths could differ significantly. This dissertation evaluates and improves global and path-level load balancing in terms of performance similarity. We achieve this with large-scale latency measurements, which not only allow us to systematically identify and evaluate the performance issues of Internet load balancing at scale, but also enable us to develop data-driven approaches to improve the performance. Specifically, this dissertation consists of three parts. First, we study the issues of existing client aggregations for global load balancing and then design AP-atoms, a data-driven client aggregation learned from passive large-scale latency measurements. Second, we show that the latency imbalance between load-balanced paths, previously deemed insignificant, is now both significant and prevalent. We present Flipr, a network prober that actively collects large-scale latency measurements to characterize the latency imbalance issue. Lastly, we design another network prober, Congi, that can detect congestion at scale and use Congi to study the congestion imbalance problem at scale. For both latency and congestion imbalance, we demonstrate that they could greatly affect the performance of various applications.PHDComputer Science & EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/168012/1/yibo_1.pd

On low-latency-capable topologies, and their impact on the design of intra-domain routing

An ISP's customers increasingly demand delivery of their traffic without congestion and with low latency. The ISP's topology, routing, and traffic engineering, often over multiple paths, together determine congestion and latency within its backbone. We first consider how to measure a topology's capacity to route traffic without congestion and with low latency. We introduce low-latency path diversity (LLPD), a metric that captures a topology's flexibility to accommodate traffic on alternative low-latency paths. We explore to what extent 116 real backbone topologies can, regardless of routing system, keep latency low when demand exceeds the shortest path's capacity. We find, perhaps surprisingly, that topologies with good LLPD are precisely those where routing schemes struggle to achieve low latency without congestion. We examine why these schemes perform poorly, and offer an existence proof that a practical routing scheme can achieve a topology's potential for congestion-free, low-delay routing. Finally we examine implications for the design of backbone topologies amenable to achieving high capacity and low delay

Design and Development of a Framework for Traffic Management in a Global Manufacturing Enterprise: The American Standard Case Study

Managed Bandwidth Services (MBSs) use Quality of Service (QoS) guarantees to effectively control traffic flows and reduce network delay. In the past, the provision of MBS in a global manufacturing enterprise was a difficult task for network administrators. However, advances in recently emerging technologies, such as Multiprotocol Label Switching (MPLS), Generalized Multiprotocol Label Switching (GMPLS), Integrated Services (IntServ), Differentiated Services (DiffServ), and Constraint-based Routing (CBR), hold promise to make MBS implementation more manageable. QoS technologies, such as DiffServ and IntServ, offer the benefits of better application performance and delivery of reliable network service. As a consequence of network traffic loads, packet congestion and latency increases still exist and must be addressed by enterprises that intend to support an MBS solution. In this investigation, the author addressed an issue that is faced by many large manufacturing enterprises, i.e., the addition of latency and congestion sensitive traffic such as Voice-over-Internet Protocol (VoIP) to networks with limited bandwidth. The goal of this research was to provide global manufacturing enterprises with a model for bandwidth management in their offices and plants. This model was based on findings from a case study of traffic management at American Standard Companies