Multi-Layer Architektur und System Design von Internet Protocol (IP) und Optischen Netzwerken

The modeling of multi-layer networks is well-researched problem, but existing models for IP-optical integration do not consider technology specific capabilities and operational aspects for employing dynamic optical circuits in IP networks. This thesis presents an ILP-based model which identifies and incorporates novel constraints for numerous technology specific aspects, such as IP forwarding capabilities and behavior of routing protocols. Novel solutions for critical operational aspects of IP-optical integration, such as optical circuit decommissioning and computation under unknown traffic conditions, are also proposed in this thesis. The thesis identifies changes in routing as a major deterrent for employing dynamic optical circuits in IP networks, and proposes the new Optical Bypass approach to address the same. Quantitative studies presented indicate that the introduction of an optical circuit under this approach significantly reduces the effect on IP routing, while lowering optical capacity requirements as compared to the traditional SPF based approaches. The proposed solution can also compute near-optimal solutions under unknown IP traffic matrix conditions, making it ideal for application in dynamic network scenarios. The thesis also addresses specific management challenges with IP-optical integration, and outlines solutions to address the same. The solutions are built around enabling coordination of management subsystems in the two network layers. The thesis presents the general architecture to facilitate coordination between management subsystems in a programmable fashion and demonstrates the capability of the architecture to be used in legacy as well as SDN-capable infrastructure. The thesis also outlines the design and implementation of the first open-source PCE, which is a critical management subsystem for enabling multi-layer path computation in IP-optical networks.Grundsätzlich ist die Modellierung von Multilayer-Netzen ein bekanntes Problem, dennoch lassen die vorhandenen Modelle für IP-optische Integration viele technologiespezifische Eigenschaften und kritische Aspekte bei Einrichtung und Betrieb dynamischer optischer Verbindungen in IP-Netzwerken außer Acht. Hierzu gehören vor allem die Eigenheiten des Forwarding, sowie das Verhalten von Routingprotokollen. Die vorliegende Dissertation präsentiert ein ILP Modell, dass solche Aspekte und Bedingungen identifiziert und integriert, sowie die Notwendigkeit hierfür anhand numerischer Evaluierung nachweist. Die Modellierungsaspekte der IP-optischen Integration umfassen bezüglich des Netzbetriebs vor allem Probleme wie die optimale Berechnung im Falle einer unbekannten Verkehrsmatrix sowie deren Verbindungsabbau. Ein wesentliches Hindernis in dynamische IP-optischen Netzwerken sind die aus ihrer Einrichtung resultierenden protokollspezifischen Änderungen im Routing. Als Lösung wird der optische Bypass vorgeschlagen. Die Untersuchungen zeigen, dass der Einsatz optischer Bypässe die Auswirkungen auf das IP-Routing stark reduziert und gleichzeitig die dafür notwendigen Kapazitätsanforderungen verringert. Damit sind optische Bypässe ebenfalls für Anwendungsszenarien geeignet, in denen die IP-Verkehrsmatrix nicht bekannt ist. Im Weiteren werden noch Probleme aus dem Bereich Netzwerkmanagement behandelt, die sich spezifisch aus der IP-optischen Integration entwickeln, und es werden entsprechende Lösungsansätze vorgestellt. Diese basieren auf der Abstimmung und dem koordinierten Betrieb der Management-Subsysteme in den beiden betroffenen Netzschichten. Gezeigt wird dann eine allgemeine Architektur, die eine Koordination von Management-Subsystemen (auch für SDN), in programmierbarer Form ermöglicht. Außerdem wird der Entwurf und die Implementierung des Open Source PCE beschrieben, welches die Berechnung von Multilayer Verbindungswegen in IP-optischen Netzwerken ermöglicht

Analyse und Optimierung von Hybriden Software-Defined Networks

Hybrid IP networks that use both control plane paradigms - distributed and centralized - promise the best of two worlds: programmability and flexible control of Software-Defined Networking (SDN), and at the same time the reliability and fault tolerance of distributed routing protocols like Open Shortest Path First (OSPF). Hybrid SDN/OSPF networks typically deploy OSPF to assure care-free operation of best effort traffic, while SDN can control prioritized traffic. This "ships-passing-in-the-night" approach, where both control planes are unaware of each other's configurations, only require hybrid SDN/OSPF routers that can participate in the domain-wide legacy routing protocol and additionally connect to a central SDN controller. This mode of operation is however known for a number of challenges in operational networks, including those related to network failures, size of forwarding tables, routing convergence time, and the increased complexity of network management. There are alternative modes of hybrid operation that provide a more holistic network control paradigm, either through an OSPF-enabled SDN controller, or a common network management system that allows the joint monitoring and configuration of both control planes, or via the partitioning of the legacy routing domain with SDN border nodes. The latter mode of operation offers to some extent to steer the working of the legacy routing protocol inside the sub-domains, which is new. The analysis, modeling, and evaluative comparison of this approach called SDN Partitioning with other modes of operation is the main contribution of this thesis. This thesis addresses important network planning tasks in hybrid SDN/OSPF networks and provides the according mathematical models to optimize network clustering, capacity planning, SDN node placement, and resource provisioning for a fault tolerant operation. It furthermore provides the mathematical models to optimize traffic engineering, failure recovery, reconfiguration scheduling, and traffic monitoring in hybrid SDN/OSPF networks, which are vital network operational tasks.Hybride IP-Netzwerke, die beide Control-Plane-Paradigmen einsetzen - verteilt und zentralisiert - versprechen das Beste aus beiden Welten: Programmierbarkeit und flexible Kontrolle des Software-Defined Networking (SDN) und gleichzeitig die Zuverlässigkeit und Fehlertoleranz von verteilten Routingprotokollen wie Open Shortest Path First (OSPF). Hybride SDN/OSPF-Netze nutzen typischerweise OSPF für die wartungsarme Bedienung des Best-Effort-Datenverkehrs, während SDN priorisierte Datenströme kontrolliert. Bei diesem Ansatz ist beiden Kontrollinstanzen die Konfiguration der jeweils anderen unbekannt, wodurch hierbei hybride SDN/OSPF Router benötigt werden, die am domänenweiten Routingprotokoll teilnehmen können und zusätzlich eine Verbindung zu einem SDN-Controller herstellen. Diese Arbeitsweise bereitet jedoch bekanntermaßen eine Reihe von Schwierigkeiten in operativen Netzen, wie zum Beispiel die Reaktion auf Störungen, die Größe der Forwarding-Tabellen, die benötigte Zeit zur Konvergenz des Routings, sowie die höhere Komplexität der Netzwerkadministration. Es existieren alternative Betriebsmodi für hybride Netze, die einen ganzheitlicheren Kontrollansatz bieten, entweder mittels OSPF-Erweiterungen im SDN-Controller, oder mittels eines übergreifenden Netzwerkmanagementsystems, dass das Monitoring und die Konfiguration aller Netzelemente erlaubt. Eine weitere Möglichkeit stellt das Clustering der ursprünglichen Routingdomäne in kleinere Subdomänen mittels SDN-Grenzknoten dar. Dieser neue Betriebsmodus erlaubt es zu einem gewissen Grad, die Operationen des Routingprotokolls in den Subdomänen zu steuern. Die Analyse, Modellierung und die vergleichende Evaluation dieses Ansatzes mit dem Namen SDN-Partitionierung und anderen hybriden Betriebsmodi ist der Hauptbeitrag dieser Dissertation. Diese Dissertation behandelt grundlegende Fragen der Netzplanung in hybriden SDN/OSPF-Netzen und beinhaltet entsprechende mathematische Modelle zur Optimierung des Clusterings, zur Kapazitätsplanung, zum Platzieren von SDN-Routern, sowie zur Bestimmung der notwendigen Ressourcen für einen fehlertoleranten Betrieb. Desweiteren enthält diese Dissertation Optimierungsmodelle für Traffic Engineering, zur Störungsbehebung, zur Ablaufplanung von Konfigurationsprozessen, sowie zum Monitoring des Datenverkehrs in hybriden SDN/OSPF-Netzen, was entscheidende Aufgaben der Netzadministration sind

Future Energy Efficient Data Centers With Disaggregated Servers

The popularity of the Internet and the demand for 24/7 services uptime is driving system performance and reliability requirements to levels that today's data centers can no longer support. This paper examines the traditional monolithic conventional server (CS) design and compares it to a new design paradigm: the disaggregated server (DS) data center design. The DS design arranges data centers resources in physical pools, such as processing, memory, and IO module pools, rather than packing each subset of such resources into a single server box. In this paper, we study energy efficient resource provisioning and virtual machine (VM) allocation in DS-based data centers compared to CS-based data centers. First, we present our new design for the photonic DS-based data center architecture, supplemented with a complete description of the architectural components. Second, we develop a mixed integer linear programming (MILP) model to optimize VM allocation for the DS-based data center, including the data center communication fabric power consumption. Our results indicate that, in DS data centers, the optimum allocation of pooled resources and their communication power yields up to 42% average savings in total power consumption when compared with the CS approach. Due to the MILP high computational complexity, we developed an energy efficient resource provisioning heuristic for DS with communication fabric (EERP-DSCF), based on the MILP model insights, with comparable power efficiency to the MILP model. With EERP-DSCF, we can extend the number of served VMs, where the MILP model scalability for a large number of VMs is challenging. Furthermore, we assess the energy efficiency of the DS design under stringent conditions by increasing the CPU to memory traffic and by including high noncommunication power consumption to determine the conditions at which the DS and CS designs become comparable in power consumption. Finally, we present a complete analysis of the communication patterns in our new DS design and some recommendations for design and implementation challenges

A survey on scheduling and mapping techniques in 3D Network-on-chip

Network-on-Chips (NoCs) have been widely employed in the design of multiprocessor system-on-chips (MPSoCs) as a scalable communication solution. NoCs enable communications between on-chip Intellectual Property (IP) cores and allow those cores to achieve higher performance by outsourcing their communication tasks. Mapping and Scheduling methodologies are key elements in assigning application tasks, allocating the tasks to the IPs, and organising communication among them to achieve some specified objectives. The goal of this paper is to present a detailed state-of-the-art of research in the field of mapping and scheduling of applications on 3D NoC, classifying the works based on several dimensions and giving some potential research directions

Energy-Aware Traffic Engineering for Wired IP Networks

RÉSUMÉ Même si l'Internet est souvent considéré comme un moyen formidable pour réduire l'impact des activités humaines sur l'environnement, sa consommation d'énergie est en train de devenir un problème en raison de la croissance exponentielle du trafic et de l'expansion rapide des infrastructures de communication dans le monde entier. En 2007, il a été estimé que les équipements de réseau (sans tenir compte de serveurs dans les centres de données) étaient responsables d'une consommation d'énergie de 22 GW, alors qu'en 2010 la consommation annuelle des plus grands fournisseurs de services Internet (par exemple AT$T) a dépassé 10 TWh par an. En raison de cette tendance alarmante, la réduction de la consommation d'énergie dans les réseaux de télécommunication, et en particulier dans les réseaux IP, est récemment devenue une priorité. Une des stratégies les plus prometteuses pour rendre plus vert l'Internet est le sleep-based energy-aware network management (SEANM), selon lequel la configuration de réseau est adaptée aux niveaux de trafic afin d'endormir tous les éléments redondantes du réseau. Dans cette thèse nous développons plusieurs approches centralisées de SEANM, afin d'optimiser la configuration de réseaux IP qui utilisent différents protocoles (OSPF or MPLS) ou transportent différents types de trafic (élastique or inélastique). Le choix d'adresser le problème d'une manière centralisée, avec une plate-forme de gestion unique qui est responsable de la configuration et de la surveillance de l'ensemble du réseau, est motivée par la nécessité d'opérateurs de maintenir en tout temps le contrôle complet sur le réseau. Visant à mettre en œuvre les approches proposées dans un environnement réaliste du réseau, nous présentons aussi un nouveau cadre de gestion de réseau entièrement configurable que nous avons appelé JNetMan. JNetMan a été exploité pour tester une version dynamique de la procédure SEANM développée pour les réseaux utilisant OSPF.----------ABSTRACT Even if the Internet is commonly considered a formidable means to reduce the impact of human activities on the environment, its energy consumption is rapidly becoming an issue due to the exponential traffic growth and the rapid expansion of communication infrastructures worldwide. Estimated consumption of the network equipment, excluding servers in data centers, in 2007 was 22 GW, while in 2010 the yearly consumption of the largest Internet Service Providers, e.g., AT&T, exceeded 10 TWh per year. The growing energy trend has motivated the development of new strategies to reduce the consumption of telecommunication networks, with particular focus on IP networks. In addition to the development of a new generation of green network equipment, a second possible strategy to optimize the IP network consumption is represented by sleep-based energy-aware network management (SEANM), which aims at adapting the whole network power consumption to the traffic levels by optimizing the network configuration and putting to sleep the redundant network elements. Device sleeping represents the main potential source of saving because the consumption of current network devices is not proportional to the utilization level: so that, the overall network consumption is constantly close to maximum. In current IP networks, quality of service (QoS) and network resilience to failures are typically guaranteed by substantially over-dimensioning the whole network infrastructure: therefore, also during peak hours, it could be possible to put to sleep a non-negligible subset of redundant network devices. Due to the heterogeneity of current network technologies, in this thesis, we focus our efforts to develop centralized SEANM approaches for IP networks operated with different configurations and protocols. More precisely, we consider networks operated with different routing schemes, namely shortest path (OSPF), flow-based (MPLS) and take into account different types of traffic, i.e., elastic or inelastic. The centralized approach, with a single management platform responsible for configuring and monitoring the whole network, is motivated by the need of network operators to be constantly in control of the network dynamics. To fully guarantee network stability, we investigate the impact of SEANM on network reliability to failures and robustness to traffic variations. Ad hoc modeling techniques are integrated within the proposed SEANM frameworks to explicitly consider resilience and robustness as network constraints. Finally, to implement the proposed procedures in a realistic network environment, we propose a novel, fully configurable network management framework, called JNetMan. We use JNetMan to develop and test a dynamic version of the SEANM procedure for IP networks operated with shortest path routing protocols

Strategies for internet route control: past, present and future

Uno de los problemas más complejos en redes de computadores es el de proporcionar garantías de calidad y confiabilidad a las comunicaciones de datos entre entidades que se encuentran en dominios distintos. Esto se debe a un amplio conjunto de razones -- las cuales serán analizadas en detalle en esta tesis -- pero de manera muy breve podemos destacar: i) la limitada flexibilidad que presenta el modelo actual de encaminamiento inter-dominio en materia de ingeniería de tráfico; ii) la naturaleza distribuida y potencialmente antagónica de las políticas de encaminamiento, las cuales son administradas individualmente y sin coordinación por cada dominio en Internet; y iii) las carencias del protocolo de encaminamiento inter-dominio utilizado en Internet, denominado BGP (Border Gateway Protocol).El objetivo de esta tesis, es precisamente el estudio y propuesta de soluciones que permitan mejorar drásticamente la calidad y confiabilidad de las comunicaciones de datos en redes conformadas por múltiples dominios.Una de las principales herramientas para lograr este fin, es tomar el control de las decisiones de encaminamiento y las posibles acciones de ingeniería de tráfico llevadas a cabo en cada dominio. Por este motivo, esta tesis explora distintas estrategias de como controlar en forma precisa y eficiente, tanto el encaminamiento como las decisiones de ingeniería de tráfico en Internet. En la actualidad este control reside principalmente en BGP, el cual como indicamos anteriormente, es uno de los principales responsables de las limitantes existentes. El paso natural sería reemplazar a BGP, pero su despliegue actual y su reconocida operatividad en muchos otros aspectos, resultan claros indicadores de que su sustitución (ó su posible evolución) será probablemente gradual. En este escenario, esta tesis propone analizar y contribuir con nuevas estrategias en materia de control de encaminamiento e ingeniería de tráfico inter-dominio en tres marcos temporales distintos: i) en la actualidad en redes IP; ii) en un futuro cercano en redes IP/MPLS (MultiProtocol Label Switching); y iii) a largo plazo en redes ópticas, modelando así una evolución progresiva y realista, facilitando el reemplazo gradual de BGP.Más concretamente, este trabajo analiza y contribuye mediante: - La propuesta de estrategias incrementales basadas en el Control Inteligente de Rutas (Intelligent Route Control, IRC) para redes IP en la actualidad. Las estrategias propuestas en este caso son de carácter incremental en el sentido de que interaccionan con BGP, solucionando varias de las carencias que éste presenta sin llegar a proponer aún su reemplazo. - La propuesta de estrategias concurrentes basadas en extender el concepto del PCE (Path Computation Element) proveniente del IETF (Internet Engineering Task Force) para redes IP/MPLS en un futuro cercano. Las estrategias propuestas en este caso son de carácter concurrente en el sentido de que no interaccionan con BGP y pueden ser desplegadas en forma paralela. En este caso, BGP continúa controlando el encaminamiento y las acciones de ingeniería de tráfico inter-dominio del tráfico IP, pero el control del tráfico IP/MPLS se efectúa en forma independiente de BGP mediante los PCEs.- La propuesta de estrategias que reemplazan completamente a BGP basadas en la incorporación de un nuevo agente de control, al cual denominamos IDRA (Inter-Domain Routing Agent). Estos agentes proporcionan un plano de control dedicado, físicamente independiente del plano de datos, y con gran capacidad computacional para las futuras redes ópticas multi-dominio.Los resultados expuestos aquí validan la efectividad de las estrategias propuestas, las cuales mejoran significativamente tanto la concepción como la performance de las actuales soluciones en el área de Control Inteligente de Rutas, del esperado PCE en un futuro cercano, y de las propuestas existentes para extender BGP al área de redes ópticas.One of the most complex problems in computer networks is how to provide guaranteed performance and reliability to the communications carried out between nodes located in different domains. This is due to several reasons -- which will be analyzed in detail in this thesis -- but in brief, this is mostly due to: i) the limited capabilities of the current inter-domain routing model in terms of Traffic Engineering (TE); ii) the distributed and potentially conflicting nature of policy-based routing, where routing policies are managed independently and without coordination among domains; and iii) the clear limitations of the inter-domain routing protocol, namely, the Border Gateway Protocol (BGP). The goal of this thesis is precisely to study and propose solutions allowing to drastically improve the performance and reliability of inter-domain communications. One of the most important tools to achieve this goal, is to control the routing and TE decisions performed by routing domains. Therefore, this thesis explores different strategies on how to control such decisions in a highly efficient and accurate way. At present, this control mostly resides in BGP, but as mentioned above, BGP is in fact one of the main causes of the existing limitations. The natural next-step would be to replace BGP, but the large installed base at present together with its recognized effectiveness in other aspects, are clear indicators that its replacement (or its possible evolution) will probably be gradually put into practice.In this framework, this thesis proposes to to study and contribute with novel strategies to control the routing and TE decisions of domains in three different time frames: i) at present in IP multi-domain networks; ii) in the near-future in IP/MPLS (MultiProtocol Label Switching) multi- domain networks; and iii) in the future optical Internet, modeling in this way a realistic and progressive evolution, facilitating the gradual replacement of BGP.More specifically, the contributions in this thesis can be summarized as follows. - We start by proposing incremental strategies based on Intelligent Route Control (IRC) solutions for IP networks. The strategies proposed in this case are incremental in the sense that they interact with BGP, and tackle several of its well-known limitations. - Then, we propose a set of concurrent route control strategies for MPLS networks, based on broadening the concept of the Path Computation Element (PCE) coming from the IETF (Internet Engineering Task Force). Our strategies are concurrent in the sense that they do not interact directly with BGP, and they can be deployed in parallel. In this case, BGP still controlls the routing and TE actions concerning regular IP-based traffic, but not how IP/MPLS paths are routed and controlled. These are handled independently by the PCEs.- We end with the proposal of a set of route control strategies for multi-domain optical networks, where BGP has been completely replaced. These strategies are supported by the introduction of a new route control element, which we named Inter-Domain Routing Agent (IDRA). These IDRAs provide a dedicated control plane, i.e., physically independent from the data plane, and with high computational capacity for future optical networks.The results obtained validate the effectiveness of the strategies proposed here, and confirm that our proposals significantly improve both the conception and performance of the current IRC solutions, the expected PCE in the near-future, as well as the existing proposals about the optical extension of BGP.Postprint (published version