Redes Definidas por Software são baseadas em características como separação entre plano de dados e plano de controle, programabilidade e monitoramento dos dispositivos, além de capacidade para teste e experimentação de novos protocolos. Embora boa parte dos conceitos dessas redes tenham sido propostos há mais de vinte e cinco anos, apenas recentemente houve um aumento no interesse pelo tópico. Esse aumento se deve principalmente ao maior poder computacional dos dispositivos e pelo surgimento do protocolo OpenFlow, proposto por um time de pesquisadores de Stanford em 2008 e considerado hoje em dia um padrão para a tecnologia. Embora o tema tenha nascido na academia, a indústria tem abraçado os conceitos e diversos fabricantes têm desenvolvido seus equipamentos com suporte ao OpenFlow. As vantagens trazidas com o OpenFlow como a pa- dronização do protocolo de comunicação entre os planos, capacidade de programação e coleta de métricas e suporte a criação de regras pró-ativas e reativas, por exemplo, fazem com que a migração de uma rede tradicional para esse novo paradigma se torne atraente. Entretanto, tal migração não é trivial. É necessário um planejamento prévio com análise dos riscos e benefícios, precisa haver acompanhamento de cada etapa da execução e validação posterior dos resultados apresentados pela rede migrada. Esta dissertação de mestrado apresenta um estudo sobre migração de tecnologias e protocolos de redes com foco na migração específica de redes tradicionais para SDN, utilizando o OpenFlow como protocolo. É apresentado um mecanismo que é capaz de analisar as configurações dos dispositivos da rede legada e convertê-las para regras de um controlador OpenFlow, possibi- litando a simulação de serviços e funcionalidades e facilitando as primeiras etapas da migração. Experimentos em ambiente de simulação mostram que uma SDN gerenciada pelo controlador confi- gurado com as regras dadas pelo mecanismo tem funcionamento equivalente àquele da rede original, não-SDN, de onde essa configuração foi extraída. / Software Defined Networks are based in characteristics such as detachment between the network data and control planes, network programmability and monitoring of the devices, as well as the ability to test and experiment new protocols. Although much of the concepts of these networks have been proposed more than twenty-five years ago, only recently has there been an interest increase for the topic. This increase is mainly due to the greater computing power of the devices and the emergence of the OpenFlow protocol, proposed by a team of Stanford researchers in 2008 and considered a standard for technology today. Although the theme was born in academia, the industry has embraced the concepts and several manufacturers have developed their equipment with OpenFlow support. The advantages of OpenFlow, such as the standardization of the communication protocol between planes, the ability to program and collect metrics, and the support for the creation of proactive and reactive rules, for example, mean that migration from a traditional network to new paradigm becomes attractive. However, such migration is not trivial. Prior planning is required with risk and benefit analysis, there must be monitoring of each stage of the execution and subsequent validation of the results presented by the migrated network. This dissertation presents a study on the migration of network technologies and protocols with focus on the specific migration of traditional networks to SDN, using OpenFlow as protocol. A mechanism is presented that is able to analyze the legacy network device settings and convert them to OpenFlow controller rules, enabling the simulation of services and features and facilitating the first steps of the migration. Experiments in the simulation environment show that a controller-managed SDN configured with the rules given by the mechanism has equivalent functionality to that of the original, non-SDN network from which this configuration was extracted from.

Current SDN controllers have been designed based on a monolithic approach that integrates all of services and applications into one single, huge program. The monolithic design of SDN controllers restricts programmers who build management applications to specific programming interfaces and services that a given SDN controller provides, making application development dependent on the controller, and thereby restricting portability of management applications across controllers. Furthermore, the monolithic approach means an SDN controller must be recompiled whenever a change is made, and does not provide an easy way to add new functionality or scale to handle large networks. To overcome the weaknesses inherent in the monolithic approach, the next generation of SDN controllers must use a distributed, microservice architecture that disaggregates the control plane by dividing the monolithic controller into a set of cooperative microservices. Disaggregation allows a programmer to choose a programming language that is appropriate for each microservice. In this dissertation, we describe steps taken towards disaggregating the SDN control plane, consider potential ways to achieve the goal, and discuss the advantages and disadvantages of each. We propose a distributed architecture that disaggregates controller software into a small controller core and a set of cooperative microservices. In addition, we present a software defined network programming framework called Umbrella that provides a set of abstractions that programmers can use for writing of SDN management applications independent of NB APIs that SDN controllers provide. Finally, we present an intent-based network programming framework called OSDF to provide a high-level policy based API for programming of network devices using SDN. <br>

There are various types of test performed on Integrated Circuits, (IC), for detecting and locating defects and faults during failure analysis. Functional, logic, parametric and IDDQ tests are among the most common. Functional IC tests are designed to verify whether the IC performs its intended function. Logic tests verify the logic operation of gates and registers. AC and DC parametric tests are used to measure time, voltage and current-varying parameters associated with the operational limits of the IC. Test parameters in parametric testing include, among others, propagation delay, operating current and signals rise and fall time. Currently, almost all ICs are manufactured or refurbished in Asia. A greater portion of the ICs are processed in China and Malaysia. Presently issues with component reliability are compromised since the ICs are not tested before they leave the factory, are sometimes only remarked with different part numbers and date codes or resold even though they do not work properly. These activities lead to a high level of uncertainty among consumers all over the world. The purpose of this research was the design of a software-defined semiconductor validation test system using the PCI eXtension for Instrumentation, (PXI), platform. The test system was to be capable of performing Open and Short Circuit Tests for CMOS components. Open and Short Circuit Tests verify for faults at the protection diode circuitry of CMOS chips level. The test system reduces the overall test timing compared to the tests performed by a functional instrument such as a curve tracer. PXI is a modular instrumentation platform originally introduced in 1997 by National Instruments, (NI). PXI is an open, PC-based platform for test, measurement and control. PXI possesses the highest bandwidth and lowest latency with modular inputs and outputs for high-resolution from DC to RF frequencies. PXI was designed for measurement and automation applications that require high-performance. Concepts associated with the Systems of Systems Engineering, (SoSE), approach were applied to this research in order to facilitate the design process for the test system. The objective was to apply Systems Engineering methodologies to the design of this particular test system.

Despite the huge success and adoption of computer networks in the recent decades, traditional network architecture falls short of some requirements by many applications. One particular shortcoming is the lack of convenient methods for providing quality of service (QoS) guarantee to various network applications. In this dissertation, we explore new Software-Defined Networking (SDN) mechanisms to provision QoS to targeted network flows. Our study contributes to providing QoS support to applications in three aspects. First, we explore using alternative routing paths for selected flows that have QoS requirements. Instead of using the default shortest path used by the current network routing protocols, we investigate using the SDN controller to install forwarding rules in switches that can achieve higher bandwidth. Second, we develop new mechanisms for guaranteeing the latency requirement by those applications depending on timely delivery of sensor data and control signals. The new mechanism pre-allocates higher priority queues in routers/switches and reserves these queues for control/sensor traffic. Third, we explore how to make the applications take advantage of the opportunity provided by SDN. In particular, we study new transmission mechanisms for big data transfer in the cloud computing environment. Instead of using a single TCP path to transfer data, we investigate how to let the application set up multiple TCP paths for the same application to achieve higher throughput. We evaluate these new mechanisms with experiments and compare them with existing approaches.

Campus networks have recently experienced a proliferation of devices ranging from personal use devices (e.g. smartphones, laptops, tablets), to special-purpose network equipment (e.g. firewalls, network address translation boxes, network caches, load balancers, virtual private network servers, and authentication servers), as well as special-purpose systems (badge readers, IP phones, cameras, location trackers, etc.). To establish directives and regulations regarding the ways in which these heterogeneous systems are allowed to interact with each other and the network infrastructure, organizations typically appoint policy writing committees (PWCs) to create acceptable use policy (AUP) documents describing the rules and behavioral guidelines that all campus network interactions must abide by. While users are the audience for AUP documents produced by an organization's PWC, network administrators are the responsible party enforcing the contents of such policies using low-level CLI instructions and configuration files that are typically difficult to understand and are almost impossible to show that they do, in fact, enforce the AUPs. In other words, mapping the contents of imprecise unstructured sentences into technical configurations is a challenging task that relies on the interpretation and expertise of the network operator carrying out the policy enforcement. Moreover, there are multiple places where policy enforcement can take place. For example, policies governing servers (e.g., web, mail, and file servers) are often encoded into the server's configuration files. However, from a security perspective, conflating policy enforcement with server configuration is a dangerous practice because minor server misconfigurations could open up avenues for security exploits. On the other hand, policies that are enforced in the network tend to rarely change over time and are often based on one-size-fits-all policies that can severely limit the fast-paced dynamics of emerging research workflows found in campus networks. This dissertation addresses the above problems by leveraging recent advances in Software-Defined Networking (SDN) to support systems that enable novel in-network approaches developed to support an organization's network security policies. Namely, we introduce PoLanCO, a human-readable yet technically-precise policy language that serves as a middle-ground between the imprecise statements found in AUPs and the technical low-level mechanisms used to implement them. Real-world examples show that PoLanCO is capable of implementing a wide range of policies found in campus networks. In addition, we also present the concept of Network Security Caps, an enforcement layer that separates server/device functionality from policy enforcement. A Network Security Cap intercepts packets coming from, and going to, servers and ensures policy compliance before allowing network devices to process packets using the traditional forwarding mechanisms. Lastly, we propose the on-demand security exceptions model to cope with the dynamics of emerging research workflows that are not suited for a one-size-fits-all security approach. In the proposed model, network users and providers establish trust relationships that can be used to temporarily bypass the policy compliance checks applied to general-purpose traffic -- typically by network appliances that perform Deep Packet Inspection, thereby creating network bottlenecks. We describe the components of a prototype exception system as well as experiments showing that through short-lived exceptions researchers can realize significant improvements for their special-purpose traffic.

<p>Ova disertacija se bavi istraživanjem problema kontinuiteta IP<br />mrežnih sesija u oblasti komunikscija u mobilnim računarskim mrežama.<br />Cilj istraživanja u okviru ove doktorske disertacije je da se definiše<br />rešenje problema mobilnosti primenjivo na heterogene bežične mreže<br />primenom metode softverski definisanog umrežavanja. U okviru<br />istraživanja prikazana je i praktična implementacija predloženog<br />rešenja. Tokom istraživanja su dobijeni rezultati koji ukazuju na potrebu<br />integracije postojećih tradicionalnih bežičnih mreža sa softverski<br />definisanim mrežama. Osnovu predloženog rešenja predstavlja<br />inkrementslan pristup u pogledu uvođenja novih SDN funkcionslnosti u<br />bežične IP mreže. Kroz implementaciju minimalnog seta SDN<br />funkcionalnosti gradi se tzv. hibridni model SDN mreže. Glavni<br />doprinos ovog istraživanja se ogleda u definisanju postupka koji će<br />omogućiti da se prevaziđe problem mobilnosti u aktuelnom konceptu<br />heterogenih bežičnih računarskih mreža. Ovakav model rešenja, pruža<br />značajan doprinos i sa aspekta ulaganja u promenu infrastrukture u<br />bežičnim mrežama. Implementacijom hibridnog modela, redukuje se<br />potreba za potpunim, ali i značajnim, uvođenjem virtuelne<br />infrastrukture bazirane na fleksibilnim softverski definisanim<br />mrežama.</p> / <p>This dissertation investigates the problem of IP networking communication<br />sessions continuity in mobile computer networks. The aim of the research within<br />this doctoral dissertation is to define a solution to the mobility problem<br />applicable to heterogeneous wireless networks using the software-defined<br />networking method. The research also demonstrates the practical<br />implementation of the proposed solution. During the research were obtained<br />results that indicate the need for integration of software-defined networks into<br />existing traditional wireless networks. The basis of the proposed solution is an<br />incremental approach in terms of introducing new SDN functionality into<br />wireless IP networks. Through the implementation of the minimal set of SDN<br />functionality, the so-called hybrid model of the SDN network is being built. The<br />main contribution of this research is reflected in the definition of a process that<br />will allow to overcome the problem of mobility in the current concept of<br />heterogeneous wireless computing networks. This solution model, also provides<br />a significant contribution from the aspect of investing in the change of<br />infrastructure in wireless networks. Implementation of the hybrid model reduces<br />the need for a complete replacement with a virtual infrastructure based on<br />flexible software-defined networks.</p>

Wireless channel characterization is important for determining both the requirements for a wireless system and its resulting reliability. Wireless systems are becoming ever more pervasive and thus are expected to operate in increasingly more cluttered environments. While these devices may be fixed in location, the channel is still far from ideal due to multipath. Under such conditions, it is desirable to have a means of taking wireless channel measurements in a low-cost and distributed manner, which is not always possible using typical channel measurement equipment. This thesis leverages a software-defined radio (SDR) platform to perform wideband wireless channel measurements. Specifically, the system can measure the scalar frequency response of a wireless channel in a distributed manner and provides measurements with an average mean-squared error of 0.018 % σ and a median error not exceeding 0.631 dB when compared to measurements taken with a vector network analyzer. This accuracy holds true in a highly multipath environment, with a measurement range of ~40 dB. The system is also capable of scaling to multiple wireless links which will be measured simultaneously (up to three links are demonstrated). After validating the measurement system, a measurement campaign is undertook using the system in a highly multipath environment to demonstrate a possible application of the system.

In this research, a new reputation-based model is utilized to disincentivize collusion of defenders and attackers in Software Defined Networks (SDN), and also, to disincentivize dishonest mining strategies in Blockchain. In the context of SDN, the model uses the reputation values assigned to each entity to disincentivize collusion with an attacker. Our analysis shows that not-colluding actions become Nash Equilibrium using the reputationbased model within a repeated game setting. In the context of Blockchain and mining, we illustrate that by using the same socio-rational model, miners not only are incentivized to conduct honest mining but also disincentivized to commit to any malicious activities against other mining pools. We therefore show that honest mining strategies become Nash Equilibrium in our setting. This thesis is laid out in the following manner. In chapter 2 an introduction to game theory is provided followed by a survey of previous works in game theoretic network security, in chapter 3 a new reputation-based model is introduced to be used within the context of a Software Defined Network (SDN), in chapter 4 a reputation-based solution concept is introduced to force cooperation by each mining entity in Blockchain, and finally, in chapter 5, the concluding remarks and future works are presented. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

This body of research focuses on supporting problem-stakeholders, decision-makers and problem-solvers faced with an ill-defined and complex real world problem. An ill-defined problem has a characteristic trait of continual refinement. That is, the definition of the problem changes throughout the problem investigation and resolution process. The central theme of this research is that a support system should provide problem stakeholders with a problem definition model for constructing and manipulating a representation of the definition of the problem as they understand it. The approach adopted herein is to first develop a problem definition model for ill-defined problems— the 6-Component problem definition model. With this model, it is then possible to move on to identifying the types of changes or modifications to the problem definition that problem stakeholders, decision makers and problem solvers may wish to explore. Importantly, there must be a connection between the surface representation of the problem and the underlying implementation of the support system. This research argues that by focusing the support system around the problem definition, it is possible to reduce the mismatch between the problem objectives and the representation of the problem that the support system offers. This research uses the Unified Modelling Language to record and explore the requirements that problem stakeholders, faced with an evolving problem definition, place on a support system. The 6-Component problem definition model is then embedded within a design for an evolutionary support system. This embedding, supported by collaboration diagrams, shows how a system using the 6-Component problem definition model will support stakeholders in their exploration, evaluation and resolution of an ill-defined and complex real-world problem. A case study provides validation of the effectiveness of the 6-Component problem definition model proposed and developed in this work. The case study uses the 6-Component problem definition model as a basis for implementing the Integration Workbench, an evolutionary support system for land-use planning. Stakeholders explore, communicate, evaluate and resolve the Tasmanian Regional Forest Agreement problem with assistance from the Integration Workbench.

<p>I analyze a large number of investment decisions based on theories that have been developed and formalized over the past 50 years. Previous work in this field unveils a number of biases which affect ones choices when the outcome is uncertain. In my thesis I find evidence of these already known biases and focus on finding rational explanations for their existence. I also introduce two unexplored biases; the homeboy bias and the menu bias.</p><p>The results clearly indicate that sophisticated investors are generally less subject to these biases. Since pension schemes in many nations are shifting towards defined contribution schemes, investment decisions and risk preferences will be of great consequence to investors’ personal economy and ability to consume, affecting the economy in general. It is therefore of great importance that policy makers do all that they can to increase investors sophistication and create a playing field which facilitates economically sound investing.</p>