The Internet has exponentially grown and now it is part of our everyday life. Internet services and applications rely on back-end servers that are deployed on local servers and data centers. With the growing use of data centers and cloud computing, the locations of these servers have been externalized and centralized, taking advantage of economies of scale. However, some applications need to define complex network topologies and require more than simple connectivity to the remote sites. Therefore, the network part of cloud computing, what is called cloud networking, needs to be improved and simplified. This thesis argues that network virtualization permits to fill the missing gap and we propose a network virtualization abstraction layer to ease the use of cloud networking for the end users. We implement a software prototype of our ideas using OpenFlow. We also evaluate our prototype with state of the art controllers that has similar functionalities for network virtualization. A second part of this thesis focuses on developing a tool for performance testing. We have improved the widely used tool pktgen with receiver functionalities. We use pktgen to generate traffic for our experiments with network virtualization. / <p>QC 20160428</p>

The advent of 5th generation of mobile networks (5G) will introduce some new challenges for the transport network. Different strategies can be employed by the network providers to address these challenges with the aim to achieve an efficient utilization of network resources. The most feasible option to achieve this goal is to introduce intelligence in the transport infrastructure by designing a flexible and programmable transport network. Network function virtualization (NFV) and dynamic resource sharing (DRS) are two possible techniques for realizing a flexible transport network. NFV allows to dynamically push network functions to different locations in the network, while DRS allows for sharing transport resources in a flexible manner. Both of these strategies can be realized by employing a programmable control framework based on software defined networking (SDN), which has implications on both the network data and control planes. However, this thesis specifically focuses on the data plane aspects of NFV and the control plane aspects of DRS. Considering the network caching as a specific example of network function, the data plane aspects of NFV are studied in terms of different architectural options for cache placement in order to see which options are the most efficient in terms of network power consumption and cost. The results presented in this thesis show that placing large-sized caches farther in the network for a large group of users is the most efficient approach. The control plane aspects of DRS are analyzed in terms of which provisioning strategy should be used for sharing a limited amount of transport resources. The analysis is presented for both a single-tenant case (i.e., where the role of service and network provider is played by the same entity), and a multi-tenant case (i.e., where a network provider manages the resources assigned to different service providers in an intelligent way). The results show that DRS performs much better than the conventional static approach (i.e., without sharing of resources), which translates into significant cost savings for the network providers. / <p>QC 20161115</p>

Modern web applications are marked by distinct networking and computing characteristics. As applications evolve, they continue to operate over a large monolithic framework of networking and computing equipment built from general-purpose microprocessors and Application Specific Integrated Circuits (ASICs) that offers few architectural choices. This dissertation presents techniques to diversify the next-generation Internet infrastructure by integrating Field-programmable Gate Arrays (FPGAs), a class of reconfigurable integrated circuits, with general-purpose microprocessor-based techniques. Specifically, our solutions are demonstrated in the context of two applications - network virtualization and distributed cluster computing. Network virtualization enables the physical network infrastructure to be shared among several logical networks to run diverse protocols and differentiated services. The design of a good network virtualization platform is challenging because the physical networking substrate must scale to support several isolated virtual networks with high packet forwarding rates and offer sufficient flexibility to customize networking features. The first major contribution of this dissertation is a novel high performance heterogeneous network virtualization system that integrates FPGAs and general-purpose CPUs. Salient features of this architecture include the ability to scale the number of virtual networks in an FPGA using existing software-based network virtualization techniques, the ability to map virtual networks to a combination of hardware and software resources on demand, and the ability to use off-chip memory resources to scale virtual router features. Partial-reconfiguration has been exploited to dynamically customize virtual networking parameters. An open software framework to describe virtual networking features using a hardware-agnostic language has been developed. Evaluation of our system using a NetFPGA card demonstrates one to two orders of improved throughput over state-of-the-art network virtualization techniques. The demand for greater computing capacity grows as web applications scale. In state-of-the-art systems, an application is scaled by parallelizing the computation on a pool of commodity hardware machines using distributed computing frameworks. Although this technique is useful, it is inefficient because the sequential nature of execution in general-purpose processors does not suit all workloads equally well. Iterative algorithms form a pervasive class of web and data mining algorithms that are poorly executed on general purpose processors due to the presence of strict synchronization barriers in distributed cluster frameworks. This dissertation presents Maestro, a heterogeneous distributed computing framework that demonstrates how FPGAs can break down such synchronization barriers using asynchronous accumulative updates. These updates allow for the accumulation of intermediate results for numerous data points without the need for iteration-based barriers. The benefits of a heterogeneous cluster are illustrated by executing a general-class of iterative algorithms on a cluster of commodity CPUs and FPGAs. Computation is dynamically prioritized to accelerate algorithm convergence. We implement a general-class of three iterative algorithms on a cluster of four FPGAs. A speedup of 7× is achieved over an implementation of asynchronous accumulative updates on a general-purpose CPU. The system offers 154× speedup versus a standard Hadoop-based CPU-workstation cluster. Improved performance is achieved by clusters of FPGAs.

Wireless network virtualization (WNV) and millimeter wave (mmW) communications are emerging as two key technologies for cellular networks. Virtualization in cellular networks enables wireless services to be decoupled from network resources (e.g., infrastructure and spectrum) so that multiple virtual networks can be built using a shared pool of network resources. At the same time, utilization of the large bandwidth available in mmW frequency band would help to overcome ongoing spectrum scarcity issues. In this context, this dissertation presents efficient frameworks for building virtual networks in sub-6 GHz and mmW bands. Towards developing the frameworks, first, we derive a closed-form expression for the downlink rate coverage probability of a typical sub-6 GHz cellular network with known base station (BS) locations and stochastic user equipment (UE) locations and channel conditions. Then, using the closed-form expression, we develop a sub-6 GHz virtual resource allocation framework that aggregates, slices, and allocates the sub-6 Ghz network resources to the virtual networks in such a way that the virtual networks' sub-6 GHz downlink coverage and rate demands are probabilistically satisfied while resource over-provisioning is minimized in the presence of uncertainty in UE locations and channel conditions. Furthermore, considering the possibility of lack of sufficient sub-6 GHz resources to satisfy the rate coverage demands of all virtual networks, we design a prioritized sub-6 GHz virtual resource allocation scheme where virtual networks are built sequentially based on their given priorities. To this end, we develop static frameworks that allocate sub-6 GHz resources in the presence of uncertainty in UE locations and channel conditions, i.e., before the UE locations and channel conditions are revealed. As a result, when a slice of a BS serves its associated UEs, it can be over-satisfied (i.e., resources left after satisfying the rate demands of all UEs) or under-satisfied (i.e., lack of resources to satisfy the rate demands of all UEs). On the other hand, it is extremely challenging to execute the entire virtual resource allocation process in real time due to the small transmission time intervals (TTIs) of cellular technologies. Taking this into consideration, we develop an efficient scheme that performs the virtual resource allocation in two phases, i.e., virtual network deployment phase (static) and statistical multiplexing phase (adaptive). In the virtual network deployment phase, sub-6 GHz resources are aggregated, sliced, and allocated to the virtual networks considering the presence of uncertainty in UE locations and channel conditions, without knowing which realization of UE locations and channel conditions will occur. Once the virtual networks are deployed, each of the aggregated BSs performs statistical multiplexing, i.e., allocates excess resources from the over-satisfied slices to the under-satisfied slices, according to the realized channel conditions of associated UEs. In this way, we further improve the sub-6 GHz resource utilization. Next, we steer our focus on the mmW virtual resource allocation process. MmW systems typically use beamforming techniques to compensate for the high pathloss. The directional communication in the presence of uncertainty in UE locations and channel conditions, make maintaining connectivity and performing initial access and cell discovery challenging. To address these challenges, we develop an efficient framework for mmW virtual network deployment and UE assignment. The deployment decisions (i.e., the required set of mmW BSs and their optimal beam directions) are taken in the presence of uncertainty in UE locations and channel conditions, i.e., before the UE locations and channel conditions are revealed. Once the virtual networks are deployed, an optimal mmW link (or a fallback sub-6 GHz link) is assigned to each UE according to the realized UE locations and channel conditions. Our numerical results demonstrate the gains brought by our proposed scheme in terms of minimizing resource over-provisioning while probabilistically satisfying virtual networks' sub-6 GHz and mmW demands in the presence of uncertainty in UE locations and channel conditions. / Doctor of Philosophy / In cellular networks, mobile network operators (MNOs) have been sharing resources (e.g., infrastructure and spectrum) as a solution to extend coverage, increase capacity, and decrease expenditures. Recently, due to the advent of 5G wireless services with enormous coverage and capacity demands and potential revenue losses due to over-provisioning to serve peak demands, the motivation for sharing and virtualization has significantly increased in cellular networks. Through wireless network virtualization (WNV), wireless services can be decoupled from the network resources so that various services can efficiently share the resources. At the same time, utilization of the large bandwidth available in millimeter wave (mmW) frequency band would help to overcome ongoing spectrum scarcity issues. However, due to the inherent features of cellular networks, i.e., the uncertainty in user equipment (UE) locations and channel conditions, enabling WNV and mmW communications in cellular networks is a challenging task. Specifically, we need to build the virtual networks in such a way that UE demands are satisfied, isolation among the virtual networks are maintained, and resource over-provisioning is minimized in the presence of uncertainty in UE locations and channel conditions. In addition, the mmW channels experience higher attenuation and blockage due to their small wavelengths compared to conventional sub-6 GHz channels. To compensate for the high pathloss, mmW systems typically use beamforming techniques. The directional communication in the presence of uncertainty in UE locations and channel conditions, make maintaining connectivity and performing initial access and cell discovery challenging. Our goal is to address these challenges and develop optimization frameworks to efficiently enable virtualization and mmW technologies in cellular networks.

Submitted by PPG Ci?ncia da Computa??o (ppgcc@pucrs.br) on 2018-12-12T11:28:20Z No. of bitstreams: 1 Romulo Reis de Oliveira_DIS.pdf: 1719302 bytes, checksum: 005f38fa0c94cb6b97ce5f6ad6ec70ed (MD5) / Approved for entry into archive by Sheila Dias (sheila.dias@pucrs.br) on 2018-12-14T11:26:14Z (GMT) No. of bitstreams: 1 Romulo Reis de Oliveira_DIS.pdf: 1719302 bytes, checksum: 005f38fa0c94cb6b97ce5f6ad6ec70ed (MD5) / Made available in DSpace on 2018-12-14T11:50:26Z (GMT). No. of bitstreams: 1 Romulo Reis de Oliveira_DIS.pdf: 1719302 bytes, checksum: 005f38fa0c94cb6b97ce5f6ad6ec70ed (MD5) Previous issue date: 2015-04-24 / Hybrid synchrony virtual networks arose by combining network virtualization, which allows the co-existence of several virtual networks in the same shared physical substrate, providing infrastructure in a flexible and economic way, with partial synchrony network architecture, which is relevant in distributed systems in order to build reliable systems. One of the main challenges in network virtualization is the efficient mapping of virtual resources in the substrate network, since it is a NP-Hard complexity problem. When considering the synchrony of virtual and physical resources it becomes more difficult to map, making it unfeasible to calculate the optimal solution in real environments. Thus, heuristic approaches are necessary for finding semi-optimal solutions faster. In this work, four heuristics for mapping hybrid synchrony virtual networks are adapted. In order to evaluate these heuristics, two sets of experiments were executed. In the first set is compared the optimal solutions with their respective semi-optimal solutions, the results show the heuristics? efficiency are better when the virtual network requests are smaller, furthermore there were some semi-optimal solution mapping costs equivalent to the optimal solution mapping cost. The second set of experiments evaluates the heuristics performance using a physical substrate closer to real context and a larger number of virtual network requests. The results of this second set of experiments demonstrate that even with a larger number of virtual requests and a larger substrate, the solutions were computed in acceptable time. / As redes virtuais de sincronia h?brida surgiram da combina??o entre a virtualiza??o de redes, a qual permite a coexist?ncia de v?rias redes virtuais no mesmo substrato f?sico compartilhado fornecendo infraestrutura de maneira flex?vel e econ?mica, e arquitetura de redes com sincronia parcial, essa relevante em sistemas distribu?dos para construir sistemas confi?veis. Um dos principais desafios em virtualiza??o de redes ? o mapeamento eficiente dos recursos virtuais na rede de substrato, pois ? um problema de complexidade NP-Dif?cil. Ao considerar a sincronia dos recursos virtuais e f?sicos, se torna mais dif?cil efetuar esse mapeamento, inviabilizando o c?lculo da solu??o ?tima em ambientes reais. Sendo assim, abordagens heur?sticas s?o necess?rias para encontrar solu??es semi-?timas de maneira mais r?pida. Neste trabalho s?o adaptadas quatro abordagens heur?sticas para efetuar o mapeamento de redes virtuais de sincronia h?brida. Para avaliar o desempenho dessas heur?sticas foram efetuados dois conjuntos de experimentos. No primeiro conjunto de experimentos s?o comparadas as solu??es ?timas e as respectivas solu??es semi-?timas, os resultados indicaram que a efici?ncia das heur?sticas s?o melhores quando as requisi??es de redes virtuais s?o menores, al?m disso houveram alguns custos de solu??es semi-?timas equivalentes ao custo de mapeamento da solu??o ?tima. O segundo conjunto de experimento avalia o desempenho das heur?sticas utilizando um substrato de rede mais pr?ximo do contexto real e um maior n?mero de requisi??es de redes virtuais. Os resultados desse segundo experimento demonstram que mesmo com um n?mero maior de requisi??es de redes virtuais e um substrato maior, as solu??es foram calculadas em tempo aceit?vel.

Overlay networks have been the subject of significant research and practical interest recently in addressing the inefficiency and ossification of the current Internet. In this thesis, we cover various aspects of overlay network design, including overlay routing algorithms, overlay network assignment and multihomed overlay networks. We also examine the behavior of overlay networks under a wide range of network settings and identify several key factors that affect the performance of overlay networks. Based on these findings, practical design guidelines are also given. Specifically, this thesis addresses the following problems: 1) Dynamic overlay routing: We perform an extensive simulation study to investigate the performance of available bandwidth-based dynamic overlay routing from three important aspects: efficiency, stability, and safety margin. Based on the findings, we propose a hybrid routing scheme that achieves good performance in all three aspects. We also examine the effects of several factors on overlay routing performance, including network load, traffic variability, link-state staleness, number of overlay hops, measurement errors, and native sharing effects. 2) Virtual network assignment: We investigate the virtual network (VN) assignment problem in the scenario of network virtualization. Specifically, we develop a basic VN assignment scheme without reconfiguration and use it as the building block for all other advanced algorithms. Subdividing heuristics and adaptive optimization strategies are presented to further improve the performance. We also develop a selective VN reconfiguration scheme that prioritizes the reconfiguration for the most critical VNs. 3) Overlay network configuration tool for PlanetLab: We develop NetFinder, an automatic overlay network configuration tool to efficiently allocate PlanetLab resources to individual overlays. NetFinder continuously monitors the resource utilization of PlanetLab and accepts a user-defined overlay topology as input and selects the set of PlanetLab nodes and their interconnection for the user overlay. 4) Multihomed overlay network: We examine the effectiveness of combining multihoming and overlay routing from the perspective of an overlay service provider (OSP). We focus on the corresponding design problem and examine, with realistic network performance and pricing data, whether the OSP can provide a network service that is profitable, better (in terms of round-trip time), and less expensive than the competing native ISPs.

OpenFlow-based testbeds have been established as an emerging field of research in order to create experimental environments that enable the development of new technologies on real network infrastructures. The bibliographic review showed that existing experimentation networks still lack mechanisms to guarantee users simplified operational forms, decoupled from the physical substrate and that are resilient. In this context, the research problem is: how to guarantee the users of OpenFlow experimentation networks an environment that allows creating virtual networks with low complexity in operation, flexible and resilient to link failures. The hypothesis that guided the study is that by integrating the tools OpenVirteX and FlowVisor and, consequently of its functionalities, the resulting framework would allow to achieving this purpose. OpenVirteX and FlowVisor are network hypervisors with distinct functionalities where the former has the use of virtual and arbitrary topologies, connectivity failure recovery, and absolute control. The FlowVisor has its main contribution in providing a wide flexibility in the definition of virtual networks. Therefore, the objective of this study was to develop a framework for OpenFlow experimentation networks, aiming to provide flexible virtual networks to users, with low complexity of the operation, having absolute control and resilient to failures. The study methodology is characterized by the hypothetical-deductive method. The procedures used to develop the proposal were: create the experimentation context, individual testing of the OpenVirteX and FlowVisor hypervisors, integration of the tools, evaluation of the framework and, finally, analysis and discussion of the results. The study confirmed some of the guiding hypothesis of the proposal since the framework was: Flexible, allowing to use any metrics of the OpenFlow header for the segmentation of virtual networks; Low complexity, because it allows to use a virtual and arbitrary topology composed of a single virtual switch corresponding to the entire physical network; Resilient to connectivity failures, because the tool was able to redefine the communication through of alternative routes. Regarding absolute control, the results refute the presence of this functionality. It was observed that providing total control of the network to the user has the impact of weakening the flexibility of the experimentation environment. / As redes de experimentação (testbeds) baseadas em OpenFlow tem-se constituído em um campo de investigação emergente, tendo em vista a necessidade de criar ambientes de experimentação que viabilizem o desenvolvimento de novas tecnologias sobre infraestruturas de redes reais. A revisão bibliográfica evidenciou que as redes de experimentação existentes, ainda, carecem de mecanismos que garantam aos usuários formas operacionais simplificadas, desacopladas do substrato físico e que sejam resilientes. Neste contexto, a problemática da investigação é: como garantir aos usuários de redes de experimentação OpenFlow um ambiente que possibilite criar redes virtuais de baixa complexidade de operação, flexíveis e resiliente a rupturas de enlaces? A hipótese que direcionou o estudo é que através da integração das ferramentas OpenVirteX e FlowVisor e, consequentemente de suas funcionalidades, o framework resultante possibilitaria atingir tal propósito. O OpenVirteX e FlowVisor são hypervisors de rede com funcionalidades distintas onde o primeiro dispõe da utilização de topologias virtuais e arbitrárias, recuperação de falhas de conectividade e controle absoluto. Já o FlowVisor tem sua principal contribuição em fornecer uma ampla flexibilidade na definição das redes virtuais. Logo, o objetivo deste estudo foi desenvolver um framework para redes de experimentação OpenFlow, objetivando proporcionar aos usuários redes virtuais flexíveis, de baixa complexidade de operacionalização, dispondo de controle absoluto e resiliente a falhas. A metodologia do estudo caracteriza-se pelo método hipotético-dedutivo. Os procedimentos aplicados para o desenvolvimento da proposta foram: a criação do contexto da experimentação, testes individuais dos hypervisors OpenVirteX e FlowVisor, integração das ferramentas, avaliação do Framework e, finalmente a análise e discussões dos resultados. O estudo realizado confirmou parte da hipótese norteadora da proposta uma vez que o framework se mostrou: Flexível, ao permitir utilizar quaisquer métricas do cabeçalho OpenFlow para a segmentação das redes virtuais; Baixa complexidade, pois permite utilizar uma topologia virtual e arbitrária composta por um único switch virtual correspondendo a totalidade da rede física; Resiliente a falhas de conectividade, pois a ferramenta se mostrou capaz de redefinir a comunicação através de rotas alternativas. No que se refere ao controle absoluto, os resultados refutam a presença dessa funcionalidade. Observou-se que disponibilizar o controle total da rede para o usuário tem o impacto de fragilizar a flexibilidade do ambiente de experimentação.

Currently a growing number of users depend on the Edge Cloud Computing Paradigm in a Metro Optical Network (MON). This has led to increased competition among the Cloud Service Providers (CPs) to supply incentives for the user through guaranteed Quality of Service (QoS). If the CP fails to guarantee the QoS for the accepted request, then the user will move to another CP. Making an informed decision dynamically in such a sensitive situation demands that the CP knows the user's application requirements. The Software Defined Networking (SDN) paradigm enabled the CP to achieve such desired requirement. Therefore, a framework called Virtual Network Embedding on SDN-based Metro Optical Network (VNE-MON) is proposed in this Thesis. The use of SDN paradigm in the framework guarantees profit to the CP as well as QoS to the user.\par The design concept of the SDN control plane, raises concerns regarding its scalability, reliability and performance compared to a traditionally distributed network. To justify concerns regarding the SDN, the performance of VNE-MON and its possible dependancy on the controller location is investigated. Several strategies are proposed and formulated using Integer Linear Programming to determine the controller location in a MON. Performance results from the assessment of the VNE-MON illustrates that it is more stable compare to GMPLS-based network. It is evident that the controller location's attributes have a significant effect on the efficacy of the accepted VN request.

Network virtualization has become a primary enabler to solve the internet ossi- fication problem. It allows to run multiple architectures or protocols on a shared physical infrastructure. One of the important aspects of network virtualization is to have a virtual network (VN) mapping technique which uses the substrate resources efficiently. Currently, there exists very few VN mapping techniques and there is no common evaluation strategy which can test these algorithms effectively. In this thesis, we advocate the need for such a tool and develop it by considering a wide spectrum of parameters and simulation scenarios. We also provide various performance metrics and do a comparison study of the existing algorithms. Based on the comparative study, we point out the positives and negatives of the existing mapping algorithms and propose a new LP formulation based on Hub location approach that efficiently allocates substrate resources to the virtual network requests. Our results show that our algorithm does better in terms of number of successful network mappings and average time to map while balancing load on the network.

Cloud Infrastructure-as-a-Service (IaaS) is a form of utility computing which has emerged with the recent innovations in the service computing and data communication technologies. Regardless of the fact that IaaS is attractive for application service providers, satisfying user requests while ensuring cloud operational objectives is a complicated task that raises several resource management challenges. Among these challenges, limited controllability over network services delivered to cloud consumers is prominent in single datacenter cloud environments. In addition, the lack of seamless service migration and optimization, poor infrastructure utilization, and unavailability of efficient fault tolerant techniques are noteworthy challenges in geographically distributed datacenter clouds. Initially in this thesis, a datacenter resource management framework is presented to address the challenge of limited controllability over cloud network traffic. The proposed framework integrates network virtualization functionalities offered by software defined networking (SDN) into cloud ecosystem. To provide rich traffic control features to IaaS consumers, control plane virtualization capabilities offered by SDN have been employed. Secondly, a quality of service (QoS) aware seamless service migration and optimization framework has been proposed in the context of geo-distributed datacenters. Focus has been given to a mobile end-user scenario where frequent cloud service migrations are required to mitigate QoS violations. Finally, an SDN-based dynamic fault restoration scheme and a shared backup-based fault protection scheme have been proposed. The fault restoration has been achieved by introducing QoS-aware reactive and shared risk link group-aware proactive path computation algorithms. Shared backup protection has been achieved by optimizing virtual and backup link embedding through a novel integer linear programming approach. The proposed solutions significantly improve bandwidth utilization in inter-datacenter networks while recovering from substrate link failures.