As the "network of network", the Internet has been playing a central and crucial role in modern society, culture, knowledge, businesses and so on in a period of over two decades by supporting a wide variety of network technologies and applications. However, due to its popularity and multi-provider nature, the future development of the Internet is limited to simple incremental updates. To address this challenge, network virtualization has been propounded as a potential candidate to provide the essential basis for the future Internet architecture. Network virtualization is capable of providing an open and flexible networking environment in which service providers are allowed to dynamically compose multiple coexisting heterogeneous virtual networks on a shared substrate network. Such a flexible environment will foster the deployment of diversified services and applications. A major challenge in network virtualization area is the Virtual Network Embedding (VNE), which aims to statically or dynamically allocate virtual nodes and virtual links on substrate resources, physical nodes and paths. Making effective use of substrate resources requires high-efficient and survivable VNE techniques. The main contribution of this thesis is two high-performance p-Cycle-based survivable virtual network embedding approaches. These approaches take advantage of p-Cycle-based protection techniques that minimize the backup resources while providing a full VN protection scheme against link and node failures.

The current Internet architecture presents a barrier to accommodate the vigorous arising demand for deploying new network services and applications. The next-generation architecture views the network virtualization as the gateway to overcome this limitation. Network virtualization promises to run efficiently and securely multiple dedicated virtual networks (VNs) over a shared physical infrastructure. Each VN is tailored to host a unique application based on the user’s preferences. This thesis addresses the problem of the efficient embedding of multiple VNs onto a shared substrate network (SN). The contribution of this thesis are twofold: First, a novel hierarchical SN management framework is proposed that efficiently selects the optimum VN mapping scheme for the requested VN from more than one proposed VN mapping candidates obtained in parallel. In order to accommodate the arbitrary architecture of the VNs, the proposed scheme divides the VN request into smaller subgraphs, and individually maps them on the SN using a variation of the exact subgraph matching techniques. Second, the physical resources pricing policy is introduced that is based on time-ofuse, that reflects the effect of resource congestion introduced by VN users. The preferences of the VN users are first represented through corresponding demand-utility functions that quantify the sensitivity of the applications hosted by the VNs to resource consumption and time-of-use. A novel model of time-varying VNs is presented, where users are allowed to up- or down-scale the requested resources to continuously maximize their utility while minimizing the VNs embedding cost. In contrast to existing solutions, the proposed work does not impose any limitations on the size or topology of the VN requests. Instead, the search is customized according to the VN size and the associated utility. Extensive simulations are then conducted to demonstrate the improvement achieved through the proposed work in terms of network utilization, the ratio of accepted VN requests and the SP profits.

Due to the existence of multiple stakeholders with conflicting goals and policies, alterations to the existing Internet architecture are now limited to simple incremental updates; deployment of any new, radically different technology is next to impossible. To fend off this ossification, network virtualization has been propounded as a diversifying attribute of the future inter-networking paradigm. In this talk, we provide an overview of the network virtualization environment (NVE) and address two basic problems in this emerging field of networking research. The identity management problem is primarily concerned with ensuring interoperability across heterogeneous identifier spaces for locating and identifying end hosts in different virtual networks. We describe the architectural and the functional components of a novel identity management framework (iMark) that enables end-to-end connectivity across heterogeneous virtual networks in the NVE without revoking their autonomy. The virtual network embedding problem deals with the mapping of virtual nodes and links onto physical network resources. We argue that the separation of the node mapping and the link mapping phases in the existing algorithms considerably reduces the solution space and degrades embedding quality. We propose coordinated node and link mapping to devise two algorithms (D-ViNE and R-ViNE) for the online version of the problem under realistic assumptions and compare their performance with the existing heuristics.

Due to the existence of multiple stakeholders with conflicting goals and policies, alterations to the existing Internet architecture are now limited to simple incremental updates; deployment of any new, radically different technology is next to impossible. To fend off this ossification, network virtualization has been propounded as a diversifying attribute of the future inter-networking paradigm. In this talk, we provide an overview of the network virtualization environment (NVE) and address two basic problems in this emerging field of networking research. The identity management problem is primarily concerned with ensuring interoperability across heterogeneous identifier spaces for locating and identifying end hosts in different virtual networks. We describe the architectural and the functional components of a novel identity management framework (iMark) that enables end-to-end connectivity across heterogeneous virtual networks in the NVE without revoking their autonomy. The virtual network embedding problem deals with the mapping of virtual nodes and links onto physical network resources. We argue that the separation of the node mapping and the link mapping phases in the existing algorithms considerably reduces the solution space and degrades embedding quality. We propose coordinated node and link mapping to devise two algorithms (D-ViNE and R-ViNE) for the online version of the problem under realistic assumptions and compare their performance with the existing heuristics.

Network virtualization and overlay networks have emerged as powerful tools for improving the flexibility of the Internet. Overlays are used to provide a wide range of useful services in today's networking environment, and they are also viewed as important building blocks for an agile and evolvable future Internet. Regardless of the specific service it provides, an overlay needs assistance in several areas in order to perform properly throughout its existence. This dissertation focuses on the mechanisms underlying the provision of auxiliary support services that perform control and management functions for overlays, such as overlay assignment, resource allocation, overlay monitoring and diagnosis. The priorities and objectives in the design of such mechanisms depend on network conditions and the virtualization environment. We identify opportunities for improvements that can help provide auxiliary services more effectively at different overlay life stages and under varying assumptions. The contributions of this dissertation are the following: 1. An overlay assignment algorithm designed to improve an overlay's diagnosability, which is defined as its property to allow accurate and low-cost fault diagnosis. The main idea is to increase meaningful sharing between overlay links in a controlled manner in order to help localize faults correctly with less effort. 2. A novel definition of bandwidth allocation fairness in the presence of multiple resource sharing overlays, and a routing optimization technique to improve fairness and the satisfaction of overlays. Evaluation analyzes the characteristics of different fair allocation algorithms, and suggests that eliminating bottlenecks via custom routing can be an effective way to improve fairness. 3. An optimization solution to minimize the total cost of monitoring an overlay by determining the optimal mix of overlay and native links to monitor, and an analysis of the effect of topological properties on monitoring cost and the composition of the optimal mix of monitored links. We call our approach multi-layer monitoring and show that it is a flexible approach producing minimal-cost solutions with low errors. 4. A study of virtual network embedding in software defined networks (SDNs), identifying the challenges and opportunities for embedding in the SDN environment, and presenting two VN embedding techniques and their evaluation. One objective is to balance the stress on substrate components, and the other is to minimize the delays between VN controllers and switches. Each technique optimizes embedding for one objective while keeping the other within bounds.

As the "network of network", the Internet has been playing a central and crucial role in modern society, culture, knowledge, businesses and so on in a period of over two decades by supporting a wide variety of network technologies and applications. However, due to its popularity and multi-provider nature, the future development of the Internet is limited to simple incremental updates. To address this challenge, network virtualization has been propounded as a potential candidate to provide the essential basis for the future Internet architecture. Network virtualization is capable of providing an open and flexible networking environment in which service providers are allowed to dynamically compose multiple coexisting heterogeneous virtual networks on a shared substrate network. Such a flexible environment will foster the deployment of diversified services and applications. A major challenge in network virtualization area is the Virtual Network Embedding (VNE), which aims to statically or dynamically allocate virtual nodes and virtual links on substrate resources, physical nodes and paths. Making effective use of substrate resources requires high-efficient and survivable VNE techniques. The main contribution of this thesis is two high-performance p-Cycle-based survivable virtual network embedding approaches. These approaches take advantage of p-Cycle-based protection techniques that minimize the backup resources while providing a full VN protection scheme against link and node failures.

The current Internet architecture presents a barrier to accommodate the vigorous arising demand for deploying new network services and applications. The next-generation architecture views the network virtualization as the gateway to overcome this limitation. Network virtualization promises to run efficiently and securely multiple dedicated virtual networks (VNs) over a shared physical infrastructure. Each VN is tailored to host a unique application based on the user’s preferences. This thesis addresses the problem of the efficient embedding of multiple VNs onto a shared substrate network (SN). The contribution of this thesis are twofold: First, a novel hierarchical SN management framework is proposed that efficiently selects the optimum VN mapping scheme for the requested VN from more than one proposed VN mapping candidates obtained in parallel. In order to accommodate the arbitrary architecture of the VNs, the proposed scheme divides the VN request into smaller subgraphs, and individually maps them on the SN using a variation of the exact subgraph matching techniques. Second, the physical resources pricing policy is introduced that is based on time-ofuse, that reflects the effect of resource congestion introduced by VN users. The preferences of the VN users are first represented through corresponding demand-utility functions that quantify the sensitivity of the applications hosted by the VNs to resource consumption and time-of-use. A novel model of time-varying VNs is presented, where users are allowed to up- or down-scale the requested resources to continuously maximize their utility while minimizing the VNs embedding cost. In contrast to existing solutions, the proposed work does not impose any limitations on the size or topology of the VN requests. Instead, the search is customized according to the VN size and the associated utility. Extensive simulations are then conducted to demonstrate the improvement achieved through the proposed work in terms of network utilization, the ratio of accepted VN requests and the SP profits.

Em ambientes de virtualização de redes (NVEs – Network Virtualization Environments), a infraestrutura física é compartilhada entre diferentes usuários (ou provedores de serviços) que criam múltiplas redes virtuais (VNs – Virtual Networks). Como parte do aprovisionamento de VNs, roteadores virtuais (VRs – Virtual Routers) são criados dentro de roteadores físicos que suportam a virtualização. Atualmente, o gerenciamento de NVEs é quase sempre realizado por soluções proprietárias, normalmente baseadas em interfaces de linha de comando (CLI – Command Line Interface). NVEs heterogêneos (i.e., com equipamentos e tecnologias diferentes) são difíceis de gerenciar, devido à falta de soluções de gerenciamento padronizadas. Como primeiro passo para conseguir a interoperabilidade de gerenciamento, bom desempenho e alta escalabilidade, foram implementadas, avaliadas e comparadas cinco interfaces de gerenciamento de roteadores físicos que hospedam roteadores virtuais. As interfaces são baseadas em SNMP (v2c e v3), NETCONF, e RESTful Web Services (sobre HTTP e HTTPS), e são projetadas para realizar três operações básicas de gerenciamento de VRs: criação de VR, recuperação de informações de VR e remoção de VR. Essas interfaces foram avaliadas em relação às seguintes métricas: tempo de resposta, tempo de CPU, consumo de memória e uso da rede. Os resultados mostram que a interface baseada no SNMPv2c é a mais adequada para pequenos NVEs, sem rigorosos requisitos de segurança, e o NETCONF é a melhor escolha para compor uma interface de gerenciamento para ser implantada em cenários mais realistas, onde a segurança e a escalabilidade são as principais preocupações. / In network virtualization environments (NVEs), the physical infrastructure is shared among different users (or service providers) who create multiple virtual networks (VNs). As part of VN provisioning, virtual routers (VRs) are created inside physical routers supporting virtualization. Currently, the management of NVEs is mostly realized by proprietary solutions, usually based on Command Line Interfaces (CLI). Heterogeneous NVEs (i.e., with different equipment and technologies) are difficult to manage due to the lack of standardized management solutions. As a first step to achieve management interoperability, good performance, and high scalability, we implemented, evaluated, and compared five management interfaces for physical routers that host virtual ones. The interfaces are based on SNMP (v2c and v3), NETCONF, and RESTful Web Services (over HTTP and HTTPS), and are designed to perform three basic VR management operations: VR creation, VR information retrieval, and VR removal. We evaluate these interfaces with regard to the following metrics: response time, CPU time, memory consumption, and network usage. Results show that the SNMPv2c interface is the most suitable one for small NVEs without strict security requirements and NETCONF is the best choice to compose a management interface to be deployed in more realistic scenarios, where security and scalability are major concerns.

A virtualização de redes tem se tornado cada vez mais proeminente nos últimos anos. Tal técnica permite a criação de infraestruturas de rede que se adaptam a necessidades específicas de aplicações de rede distintas, além de dar suporte à instanciação de ambientes favoráveis para o desenvolvimento e avaliação de novas arquiteturas e protocolos. Apesar de esforços recentes (motivados principalmente pela busca de mecanismos para avaliar propostas relacionadas à Internet do Futuro) terem contribuído substancialmente para a materialização desse conceito, nenhum preocupou-se em conciliar alocação eficiente de recursos e satisfação de requisitos de segurança (e.g., confidencialidade). É importante ressaltar que, no contexto de redes virtuais, a proteção de infraestruturas de rede compartilhadas constitui condição fundamental para seu uso em larga escala. É de grande importância que o impacto negativo causado pelo aprovisionamento de segurança seja considerado no processo de mapeamento de redes virtuais, de forma a permitir o uso integral dos recursos físicos sem subestimar requisitos de capacidade. Portanto, nesta dissertação, são propostos um modelo ótimo e um al- goritmo heurístico para realizar o mapeamento de redes virtuais em substratos físicos que têm por objetivo otimizar a utilização de recursos físicos garantindo a satisfação de requisitos de segurança. Ambas as abordagens possuem uma modelagem precisa de custos adicionais associados a mecanismos de segurança usados para proteger re- des virtuais, e são capazes de atender requisições de redes virtuais de forma online. Além disso, são apresentados os resultados de um extensivo processo de avaliação realizado, incluindo uma comparação detalhada entre o modelo ótimo e o algoritmo heurístico. Os experimentos revelam que o modelo baseado em Programação Linear Inteira é capaz de alocar redes virtuais de forma ótima em substratos físicos com até cem roteadores, enquanto que o algoritmo heurístico é capaz de adaptar-se a infraestruturas maiores, provendo mapeamentos sub-ótimos em um curto espaço de tempo. / Network virtualization has become increasingly prominent in recent years. It enables the creation of network infrastructures that are specifically tailored to the needs of distinct network applications and supports the instantiation of favorable en- vironments for the development and evaluation of new architectures and protocols. Although recent efforts (motivated mainly by the search for mechanisms to eval- uate Future Internet proposals) have contributed substantially to materialize this concept, none of them has attempted to combine efficient resource mapping with ful- fillment of security requirements (e.g., confidentiality). It is important to note that, in the context of virtual networks, the protection of shared network infrastructures constitutes a fundamental condition to enable its use in large scale. Considering the negative impact of security provisions in the virtual network embedding process is of paramount importance in order to fully utilize physical re- sources without underestimating capacity requirements. Therefore, in this thesis we propose both an optimal model and a heuristic algorithm for embedding virtual networks on physical substrates that aim to optimize physical resource usage while meeting security requirements. Both approaches feature precise modeling of over- head costs of security mechanisms used to protect virtual networks, and are able to handle virtual network requests in an online manner. In addition, we present the results of an extensive evaluation we carried out, including a detailed comparison of both the optimal model and the heuristic algorithm. Our experiments show that the Integer Linear Programming (ILP) model is capable of optimally embedding virtual networks on physical infrastructures with up to a hundred routers, while the heuristic algorithm is capable of scaling to larger infrastructures, providing timely, sub-optimal mappings.

A virtualização de redes é uma solução proposta para superar a chamada ossificação da Internet pois permite o desenvolvimento de novas arquiteturas de rede de forma flexível e controlada. Com a virtualização de redes, é possível criar múltiplas redes virtuais operando simultaneamente em uma infraestrutura física compartilhada. No entanto, o gerenciamento de redes com suporte a virtualização apresenta desafios que precisam ser resolvidos para obter um ambiente de rede confiável e funcional. Um dos principais aspectos relacionados ao gerenciamento de ambientes de virtualização de redes diz respeito ao aprovisionamento de redes virtuais. O aprovisionamento de redes virtuais define como os recursos de rede virtuais (nós e enlaces) são alocados na infraestrutura física. O aprovisionamento de redes virtuais é comumente baseado em algoritmos de mapeamento que possuem objetivos bem definidos como reduzir o custo de alocação, realizar balanceamento de carga ou minimizar o consumo de energia. Embora redes virtuais compartilhem a mesma infraestrutura, elas tipicamente são utilizadas para hospedar várias aplicações que possuem diferentes objetivos. Infelizmente, as soluções de aprovisionamento atuais focam em um único ou em um conjunto muito limitado de objetivos que podem não ser capazes de satisfazer os requisitos de um número cada vez mais crescente de aplicações. Novas aplicações podem exigir objetivos diferentes dos que são suportados pelo sistema de aprovisionamento que está em operação em uma infraestrutura de virtualização de redes. Nesta tese, o problema de Aprovisionamento de Redes Virtuais Orientado à Aplicação é formulado e um arcabouço de aprovisionamento adaptativo para redes virtualizadas que considera as caracteristicas de várias aplicações bem como seus requisitos de desempenho é proposto. O arcabouço proposto é baseado no conceito de paradigma de alocação, que é um conjunto de políticas de aprovisionamento que guiam o processo de alocação de recursos. Um paradigma traduz objetivos de Provedores de Infraestrutura e Provedores de Serviço para ações de alocação individuais que criam as redes virtuais. Uma linguagem de políticas para paradigmas é também definida para expressar o relacionamento entre paradigmas, objetivos e ações. Para determinar a eficiência de um paradigma de alocação, é proposto um modelo para quantificar o desempenho de redes virtuais que é baseado em dados coletados de sistemas de benchmarking aplicados no contexto de ambientes virtualizados. O modelo proposto é capaz de calcular o desempenho das redes virtuais alocadas e influenciar mudanças em paradigmas de alocação. Simulações foram conduzidas para verificar a viabilidade da solução proposta e comparar diferentes paradigmas de alocação. Resultados mostram que o uso de paradigmas de alocação pode ajudar administradores de ambientes de virtualização de redes a escolher a melhor estratégia de alocação dado um conjunto de objetivos definidos pelos Provedores de Infraestrutura e pelos Provedores de Serviço. / Network virtualization is a feasible solution to tackle the so-called Internet ossification by enabling the deployment of novel network architectures in a flexible and controlled way. With network virtualization, it is possible to have multiple virtual networks (VNs) running simultaneously on top of a shared physical infrastructure. Network management with virtualization support, however, poses challenges that need to be addressed in order to fully achieve an effective and reliable networking environment. One of the main aspects related to the management of network virtualization environments is virtual network provisioning. Virtual network provisioning defines how virtual network resources (nodes and links) are allocated in the physical infrastructure. VN provisioning often relies on embedding algorithms that aim to achieve well defined objectives, such as reducing allocation cost, load balancing, or minimizing energy consumption. Although VNs share the same infrastructure, they typically host diverse applications with different goals. Unfortunately, current provisioning solutions focus on a single or a limited set of objectives that may not simultaneously match the requirements of an increasing number of applications deployed in networks everyday. Novel applications may require different objectives that are not supported by the active provisioning system. In this thesis, we formulate the Application-Aware Virtual Network Provisioning Problem (AVNP) and propose an adaptive provisioning framework for virtualized networks that takes into consideration the characteristics of multiple applications and their distinct performance objectives. The proposed framework is based on the concept of allocation paradigm, which is defined as a set of provisioning policies that guide the resource allocation process. A paradigm translates objectives from both Infrastructure Providers (InPs) and Service Providers (SPs) to individual allocation actions that actually provision VNs. A policy language is also defined to express the relationship between paradigms, objectives, and actions. To determine the efficiency of a particular paradigm, we propose a virtual network performance computation model based on data measured from existing virtualization benchmarks. The model is able to quantify the performance of allocated VNs and guide paradigm changing decisions. Extensive simulations were performed to verify the viability of the proposed solution and compare different paradigms. Results show the feasibility of allocation paradigms in helping network providers to select the best provisioning strategy given a set of InP/SP objectives.