52 research outputs found
Resilience mechanisms for carrier-grade networks
In recent years, the advent of new Future Internet (FI) applications is creating ever-demanding requirements. These requirements are pushing network carriers for high transport capacity, energy efficiency, as well as high-availability services with low latency. A widespread practice to provide FI services is the adoption of a multi-layer network model consisting in the use of IP/MPLS and optical technologies such as Wavelength Division Multiplexing (WDM).
Indeed, optical transport technologies are the foundation supporting the current telecommunication network backbones, because of the high transmission bandwidth achieved in fiber optical networks. Traditional optical networks consist of a fixed 50 GHz grid, resulting in a low Optical Spectrum (OS) utilization, specifically with transmission rates above 100 Gbps. Recently, optical networks have been undergoing significant changes with the purpose of providing a flexible grid that can fully exploit the potential of optical networks. This has led to a new network paradigm termed as Elastic Optical Network (EON).
In recent years, the advent of new Future Internet (FI) applications is creating ever-demanding requirements. A widespread practice to provide FI services is the adoption of a multi-layer network model consisting in the use of IP/MPLS and optical technologies such as Wavelength Division Multiplexing (WDM). Traditional optical networks consist of a fixed 50 GHz grid, resulting in a low Optical Spectrum (OS) utilization. Recently, optical networks have been undergoing significant changes with the purpose of providing a flexible grid that can fully exploit the potential of optical networks. This has led to a new network paradigm termed as Elastic Optical Network (EON). Recently, a new protection scheme referred to as Network Coding Protection (NCP) has emerged as an innovative solution to proactively enable protection in an agile and efficient manner by means of throughput improvement techniques such as Network Coding. It is an intuitive reasoning that the throughput advantages of NCP might be magnified by means of the flexible-grid provided by EONs.
The goal of this thesis is three-fold. The first, is to study the advantages of NCP schemes in planning scenarios. For this purpose, this thesis focuses on the performance of NCP assuming both a fixed as well as a flexible spectrum grid. However, conversely to planning scenarios, in dynamic scenarios the accuracy of Network State Information (NSI) is crucial since inaccurate NSI might substantially affect the performance of an NCP scheme. The second contribution of this thesis is to study the performance of protection schemes in dynamic scenarios considering inaccurate NSI. For this purpose, this thesis explores prediction techniques in order to mitigate the negative effects of inaccurate NSI.
On the other hand, Internet users are continuously demanding new requirements that cannot be supported by the current host-oriented communication model.This communication model is not suitable for future Internet architectures such as the so-called Internet of Things (IoT). Fortunately, there is a new trend in network research referred to as ID/Locator Split Architectures (ILSAs) which is a non-disruptive technique to mitigate the issues related to host-oriented communications. Moreover, a new routing architecture referred to as Path Computation Element (PCE) has emerged with the aim of overcoming the well-known issues of the current routing schemes. Undoubtedly, routing and protection schemes need to be enhanced to fully exploit the advantages provided by new network architectures.In light of this, the third goal of this thesis introduces a novel PCE-like architecture termed as Context-Aware PCE. In a context-aware PCE scenario, the driver of a path computation is not a host/location, as in conventional PCE architectures, rather it is an interest for a service defined within a context.En los últimos años la llegada de nuevas aplicaciones del llamado Internet del Futuro (FI) está creando requerimientos sumamente exigentes. Estos requerimientos están empujando a los proveedores de redes a incrementar sus capacidades de transporte, eficiencia energética, y sus prestaciones de servicios de alta disponibilidad con baja latencia. Es una práctica sumamente extendida para proveer servicios (FI) la adopción de un modelo multi-capa el cual consiste en el uso de tecnologías IP/MPLS así como también ópticas como por ejemplo Wavelength Division Multiplexing (WDM). De hecho, las tecnologías de transporte son el sustento del backbone de las redes de telecomunicaciones actuales debido al gran ancho de banda que proveen las redes de fibra óptica. Las redes ópticas tradicionales consisten en el uso de un espectro fijo de 50 GHz. Esto resulta en una baja utilización del espectro Óptico, específicamente con tasas de transmisiones superiores a 100 Gbps. Recientemente, las redes ópticas están experimentado cambios significativos con el propósito de proveer un espectro flexible que pueda explotar el potencial de las redes ópticas. Esto ha llevado a un nuevo paradigma denominado Redes Ópticas Elásticas (EON). Por otro lado, un nuevo esquema de protección llamado Network Coding Protection (NCP) ha emergido como una solución innovadora para habilitar de manera proactiva protección eficiente y ágil usando técnicas de mejora de throughput como es Network Coding (NC). Es un razonamiento lógico pensar que las ventajas relacionadas con throughput de NCP pueden ser magnificadas mediante el espectro flexible proveído por las redes EONs. El objetivo de esta tesis es triple. El primero es estudiar las ventajas de esquemas NCP en un escenario de planificación. Para este propósito, esta tesis se enfoca en el rendimiento de NCP asumiendo un espectro fijo y un espectro flexible. Sin embargo, contrario a escenarios de planificación, en escenarios dinámicos la precisión relacionada de la Información de Estado de Red (NSI) es crucial, ya que la imprecisión de NSI puede afectar sustancialmente el rendimiento de un esquema NCP. La segunda contribución de esta tesis es el estudio del rendimiento de esquemas de protección en escenarios dinámicos considerando NSI no precisa. Para este propósito, esta tesis explora técnicas predictivas con el propósito de mitigar los efectos negativos de NSI impreciso. Por otro lado, los usuarios de Internet están demandando continuamente nuevos requerimientos los cuales no pueden ser soportados por el modelo de comunicación orientado a hosts. Este modelo de comunicaciones no es factible para arquitecturas FI como es el Internet de las cosas (IoT). Afortunadamente, existe un nueva línea investigativa llamada ID/Locator Split Architectures (ILSAs) la cual es una técnica no disruptiva para mitigar los problemas relacionadas con el modelo de comunicación orientado a hosts. Además, un nuevo esquema de enrutamiento llamado as Path Computation Element (PCE) ha emergido con el propósito de superar los problemas bien conocidos de los esquemas de enrutamiento tradicionales. Indudablemente, los esquemas de enrutamiento y protección deben ser mejorados para que estos puedan explotar las ventajas introducidas por las nuevas arquitecturas de redes. A luz de esto, el tercer objetivo de esta tesis es introducir una nueva arquitectura PCE denominada Context-Aware PCE. En un escenario context-aware PCE, el objetivo de una acción de computación de camino no es un host o localidad, como es el caso en lo esquemas PCE tradicionales. Más bien, es un interés por un servicio definido dentro de una información de contexto
Optical flow switched networks
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.Includes bibliographical references (p. 253-279).In the four decades since optical fiber was introduced as a communications medium, optical networking has revolutionized the telecommunications landscape. It has enabled the Internet as we know it today, and is central to the realization of Network-Centric Warfare in the defense world. Sustained exponential growth in communications bandwidth demand, however, is requiring that the nexus of innovation in optical networking continue, in order to ensure cost-effective communications in the future. In this thesis, we present Optical Flow Switching (OFS) as a key enabler of scalable future optical networks. The general idea behind OFS-agile, end-to-end, all-optical connections-is decades old, if not as old as the field of optical networking itself. However, owing to the absence of an application for it, OFS remained an underdeveloped idea-bereft of how it could be implemented, how well it would perform, and how much it would cost relative to other architectures. The contributions of this thesis are in providing partial answers to these three broad questions. With respect to implementation, we address the physical layer design of OFS in the metro-area and access, and develop sensible scheduling algorithms for OFS communication. Our performance study comprises a comparative capacity analysis for the wide-area, as well as an analytical approximation of the throughput-delay tradeoff offered by OFS for inter-MAN communication. Lastly, with regard to the economics of OFS, we employ an approximate capital expenditure model, which enables a throughput-cost comparison of OFS with other prominent candidate architectures. Our conclusions point to the fact that OFS offers significant advantage over other architectures in economic scalability.(cont.) In particular, for sufficiently heavy traffic, OFS handles large transactions at far lower cost than other optical network architectures. In light of the increasing importance of large transactions in both commercial and defense networks, we conclude that OFS may be crucial to the future viability of optical networking.by Guy E. Weichenberg.Ph.D
Organizational identity, organizational capabilities, and the evolution of the multinational corporation : JTech's transmission systems business in the US
Thesis (Ph. D.)--Massachusetts Institute of Technology, Sloan School of Management, 2007."June 2007."Includes bibliographical references (v. 2, leaves 259-267).When a multinational corporation (MNC) internationalizes by establishing a new subsidiary, the subsidiary's evolution depends upon its acceptance within its host country environment, by its home country headquarters, by other subsidiaries, and by all other stakeholders, including employees, suppliers, customers, complementary innovators, product market critics and analysts. To be accepted, the subsidiary organization has to have a legitimate form with some combination of properties - such as activities, features, and boundaries - that make it recognizable and understandable as a meaningful social unit. In short, as a social object, the subsidiary has to have an identity that conforms to a recognized and accepted type, so that it is evaluated positively as belonging to a legitimate category of organizations. Yet, if value creation simultaneously depends upon a subsidiary developing organizational capabilities, how does its identity shape the development of those capabilities? How do the capabilities in turn alter the subsidiary's identity? How does the identity-capability relationship influence the subsidiary's strategy, and how do the organizational structures put in place to cope with these changes affect the organization's identity and legitimacy? I explore these issues by analyzing the case of the evolution of a US subsidiary of a Japanese high technology MNC, which had responsibility for activities related to the development and sale of transmission equipment into the US, over a fifteen year period ending in 2000. I find that organizational members constructed an identity for their organization through which they enacted their environment, organizational capabilities, strategy, and structure.(cont.) These, in turn, recursively interacted with the organizational identity in complex ways, either reinforcing the salient organizational identity or stressing it, resulting in identity work through which organizational members sought to reconstruct a new and legitimate organizational identity. Understanding the identity of a subsidiary is necessary in efforts to improve the effectiveness of managing across borders. As a corollary, management practices designed to improve collaboration, such as facilitating the transfer of more complex information, or that aim to deepen understanding among collaborating units of an MNC, such as increasing personnel transfers, may actually undermine cross-border knowledge development through their negative effect on organizational identity.by Christopher J. Voisey.Ph.D
Optical Wireless Data Center Networks
Bandwidth and computation-intensive Big Data applications in disciplines like social media, bio- and nano-informatics, Internet-of-Things (IoT), and real-time analytics, are pushing existing access and core (backbone) networks as well as Data Center Networks (DCNs) to their limits. Next generation DCNs must support continuously increasing network traffic while satisfying minimum performance requirements of latency, reliability, flexibility and scalability. Therefore, a larger number of cables (i.e., copper-cables and fiber optics) may be required in conventional wired DCNs. In addition to limiting the possible topologies, large number of cables may result into design and development problems related to wire ducting and maintenance, heat dissipation, and power consumption.
To address the cabling complexity in wired DCNs, we propose OWCells, a class of optical wireless cellular data center network architectures in which fixed line of sight (LOS) optical wireless communication (OWC) links are used to connect the racks arranged in regular polygonal topologies. We present the OWCell DCN architecture, develop its theoretical underpinnings, and investigate routing protocols and OWC transceiver design. To realize a fully wireless DCN, servers in racks must also be connected using OWC links. There is, however, a difficulty of connecting multiple adjacent network components, such as servers in a rack, using point-to-point LOS links. To overcome this problem, we propose and validate the feasibility of an FSO-Bus to connect multiple adjacent network components using NLOS point-to-point OWC links. Finally, to complete the design of the OWC transceiver, we develop a new class of strictly and rearrangeably non-blocking multicast optical switches in which multicast is performed efficiently at the physical optical (lower) layer rather than upper layers (e.g., application layer).
Advisors: Jitender S. Deogun and Dennis R. Alexande
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ReSCon '12, Research Student Conference: Book of Abstracts
The fifth SED Research Student Conference (ReSCon2012) was hosted over three days, 18-20 June 2012, in the Hamilton Centre at Brunel University. The conference consisted of 130 oral and 70 poster presentations, based on the high quality and diverse research being conducted within the School of Engineering and Design by postgraduate research students. The conference is held annually, and ReSCon plays a key role in contributing to research and innovations within the School
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