Spelling suggestions: "subject:"defined"" "subject:"efined""
491 |
Análisis de la determinación de los aportes en el Sistema Privado de Pensiones peruano: una aplicación de anualidades y perpetuidades / Analysis of the Determination of Contributions in the Peruvian Private Pension System: An Application of Annuities and PerpetuitiesQuintana Meza, Aldo 10 April 2018 (has links)
This paper discusses on how to set fixed contributions for a given objective of a private pension plan, by using two traditional financial models such as annuities and perpetuities. The private pension plan has two components: (i) the contributions’ plan on a monthly basis (annuity), and (ii) the pension plan on a monthly basis (perpetuity). The document focuses on the relationship between the size to the contribution and the pension fund returns. The document covers the Peruvian case. / Este artículo discute cómo establecer los aportes fijos para un determinado objetivo de un plan de pensiones privado, mediante el uso de dos modelos financieros tradicionales como las anualidades y perpetuidades. El plan de pensiones privado tiene dos componentes: (i) el plan de aportes sobre una base mensual (anualidad), y (ii) el plan de pensiones sobre una base mensual (perpetuidad). El documento se centra en la relación entre el tamaño de la contribución y los rendimientos de los fondos de pensiones. Ello se concentrará específicamente en el caso peruano.
|
492 |
Étude de relais multi-mode sous contrainte d'énergie dans un contexte de radio logicielle / Study of multi-mode relay under energetic constraints in the context of software radioLévy-Bencheton, Cédric 28 June 2011 (has links)
La réduction d’énergie apparaît comme un besoin crucial dans les télécommunications modernes, tant au niveau des terminaux que des réseaux. Dans les réseaux modernes, un terminal peut se connecter à Internet via d’autres terminaux ou infrastructures à proximité, appelés relais. Bien que les relais offrent une solution intéressante pour limiter la puissance de transmission des terminaux, il n’est pas simple de garantir une réduction de la consommation d’énergie globale. Il devient alors nécessaire de développer des outils pour évaluer et quantifier la consommation d’énergie. Un terminal moderne dispose de plusieurs interfaces de communications, ce qui lui permet d’utiliser plusieurs standards. Sachant qu’un standard dispose de différents modes de communications, un terminal est multi-mode lorsqu’il possède cette capacité à communiquer sur les différents standards et modes disponibles. Nous nous sommes alors intéressés à l’utilisation du multi-mode dans le cadre des relais. Nous nous positionnons dans un contexte de radio logicielle, où la couche physique d’un terminal est représentée par des blocs programmables, ce qui facilite l’implémentation du multi-mode. Afin d’estimer la consommation d’énergie d’une radio logicielle, nous avons calculé la complexité algorithmique pour les couches physiques du 802.11g (ou Wi-Fi), de l’UMTS et du 802.15.4 (ou Zigbee). Dans cette thèse, nous avons développé des outils nous permettant d’évaluer l’intérêt d’un relais multi-mode dans la réduction d’énergie. Nous avons proposé un modèle d’énergie réaliste pour le multi-mode, qui prend en compte la couche d’accès au medium des protocoles considérés. Dans un but de réalisme accru, nous avons implémenté le multi-mode au sein de WSNet, un simulateur réseau précis, grâce auquel nous avons déterminé les paramètres ayant un impact sur la consommation d’énergie. Puis, nous avons proposé et validé des stratégies permettant de minimiser l’influence de ces paramètres. / Energy reduction appears as a crucial need in modern telecommunications, be it for the terminals or the network. In modern networks, a terminal can connect to the Internet through other terminals or infrastructures in their proximity, called relays. Even though these relays appear as an interesting solution by limiting the terminals transmission power output, the reduction of energy consumption is not a simple task to ensure. Hence, it becomes necessary to develop adapted tools in order to evaluate and quantify the energy consumption. A modern terminal features several communication interfaces, which allows it to use different standards. With each standard featuring different communication modes, a multi-mode terminal has the capacity to communicate on these different modes and standard available. Hence, we have been studying how this multi-mode property can lead to energy reduction in combination with relaying. Our study is realized in the context of software defined radio, in which the physical layer is represented by programmable software blocks. Thus, software defined radio allows an eased implementation of multi-mode. In order to estimate the energy consumption of a software defined radio, we have evaluated the algorithmic complexity for the physical layers of the following standards : 802.11g (or Wi-Fi), UMTS and 802.15.4 (or Zigbee). In this thesis, we have developed the tools to evaluate the energy consumption of a multimode relay. Firstly, we have proposed a realistic energy model for multi-mode, which takes into account the media access control layer of the protocols studied. In order to increase realism, we have implemented multi-mode in WSNet, a precise network simulator, which we have used to determine the parameters impacting the energy consumption. Then, we have proposed and validated different strategies allowing us to minimize the influence of these parameters.
|
493 |
Energy Efficient Traffic Engineering in Software Defined Networks / Ingénierie de trafic pour des réseaux énergétiquement efficacesCarpa, Radu 26 October 2017 (has links)
Ce travail a pour but d'améliorer l'efficacité énergétique des réseaux de cœur en éteignant un sous-ensemble de liens par une approche SDN (Software Defined Network). Nous nous différencions des nombreux travaux de ce domaine par une réactivité accrue aux variations des conditions réseaux. Cela a été rendu possible grâce à une complexité calculatoire réduite et une attention particulière au surcoût induit par les échanges de données. Pour valider les solutions proposées, nous les avons testées sur une plateforme spécialement construite à cet effet.Dans la première partie de cette thèse, nous présentons l'architecture logicielle ``SegmenT Routing based Energy Efficient Traffic Engineering'' (STREETE). Le cœur de la solution repose sur un re-routage dynamique du trafic en fonction de la charge du réseau dans le but d'éteindre certains liens peu utilisés. Cette solution utilise des algorithmes de graphes dynamiques pour réduire la complexité calculatoire et atteindre des temps de calcul de l'ordre des millisecondes sur un réseau de 50 nœuds. Nos solutions ont aussi été validées sur une plateforme de test comprenant le contrôleur SDN ONOS et des commutateurs OpenFlow. Nous comparons nos algorithmes aux solutions optimales obtenues grâce à des techniques de programmation linéaires en nombres entiers et montrons que le nombre de liens allumés peut être efficacement réduit pour diminuer la consommation électrique tout en évitant de surcharger le réseau.Dans la deuxième partie de cette thèse, nous cherchons à améliorer la performance de STREETE dans le cas d’une forte charge, qui ne peut pas être écoulée par le réseau si des algorithmes de routages à plus courts chemins sont utilisés. Nous analysons des méthodes d'équilibrage de charge pour obtenir un placement presque optimal des flux dans le réseau.Dans la dernière partie, nous évaluons la combinaison des deux techniques proposées précédemment : STREETE avec équilibrage de charge. Ensuite, nous utilisons notre plateforme de test pour analyser l'impact de re-routages fréquents sur les flux TCP. Cela nous permet de donner des indications sur des améliorations à prendre en compte afin d'éviter des instabilités causées par des basculements incontrôlés des flux réseau entre des chemins alternatifs. Nous croyons à l'importance de fournir des résultats reproductibles à la communauté scientifique. Ainsi, une grande partie des résultats présentés dans cette thèse peuvent être facilement reproduits à l'aide des instructions et logiciels fournis. / This work seeks to improve the energy efficiency of backbone networks by automatically managing the paths of network flows to reduce the over-provisioning. Compared to numerous works in this field, we stand out by focusing on low computational complexity and smooth deployment of the proposed solution in the context of Software Defined Networks (SDN). To ensure that we meet these requirements, we validate the proposed solutions on a network testbed built for this purpose. Moreover, we believe that it is indispensable for the research community in computer science to improve the reproducibility of experiments. Thus, one can reproduce most of the results presented in this thesis by following a couple of simple steps. In the first part of this thesis, we present a framework for putting links and line cards into sleep mode during off-peak periods and rapidly bringing them back on when more network capacity is needed. The solution, which we term ``SegmenT Routing based Energy Efficient Traffic Engineering'' (STREETE), was implemented using state-of-art dynamic graph algorithms. STREETE achieves execution times of tens of milliseconds on a 50-node network. The approach was also validated on a testbed using the ONOS SDN controller along with OpenFlow switches. We compared our algorithm against optimal solutions obtained via a Mixed Integer Linear Programming (MILP) model to demonstrate that it can effectively prevent network congestion, avoid turning-on unneeded links, and provide excellent energy-efficiency. The second part of this thesis studies solutions for maximizing the utilization of existing components to extend the STREETE framework to workloads that are not very well handled by its original form. This includes the high network loads that cannot be routed through the network without a fine-grained management of the flows. In this part, we diverge from the shortest path routing, which is traditionally used in computer networks, and perform a particular load balancing of the network flows. In the last part of this thesis, we combine STREETE with the proposed load balancing technique and evaluate the performance of this combination both regarding turned-off links and in its ability to keep the network out of congestion. After that, we use our network testbed to evaluate the impact of our solutions on the TCP flows and provide an intuition about the additional constraints that must be considered to avoid instabilities due to traffic oscillations between multiple paths.
|
494 |
Infraestrutura para operações de Offloading computacional em ambiente integrado Cloudlet-SDN com suporte a mobilidadeFRANÇA, Adriano Henrique de Melo 29 August 2016 (has links)
Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-04-25T12:03:54Z
No. of bitstreams: 2
license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5)
Dissertacao_AdrianoHenrique.pdf: 1956295 bytes, checksum: 38ce5d73db0d44416c8653e58120f11c (MD5) / Made available in DSpace on 2017-04-25T12:03:55Z (GMT). No. of bitstreams: 2
license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5)
Dissertacao_AdrianoHenrique.pdf: 1956295 bytes, checksum: 38ce5d73db0d44416c8653e58120f11c (MD5)
Previous issue date: 2016-08-29 / Apesar da grande evolução tecnológica nos hardwares dos dispositivos móveis e
nas redes sem fio, ainda existem grandes limitações nesses dispositivos em termos
de processamento, capacidade de armazenamento e autonomia de energia, quando
comparados aos desktops e servidores. O paradigma de Computação em Nuvem
Móvel (MCC – Mobile Cloud Computing) permite estender os recursos
computacionais dos dispositivos móveis através da utilização das técnicas de
offloading computacional possibilitando um melhor desempenho as aplicações e
uma redução no consumo das baterias dos dispositivos. Entretanto, a técnica de
offloading nem sempre traz benefícios para o dispositivo móvel em situações de
constante mobilidade do usuário, já que cada mudança de rede requer que o
processo de offloading seja refeito. Esta dissertação propõe uma solução para
otimizar o consumo de energia e o tempo de resposta durante as operações de
offloading computacional quando o dispositivo muda de ponto de acesso. A proposta
considera um esquema de gerenciamento de mobilidade baseado em Software
Defined Networking (SDN) e técnica de caching remoto, que permite ao usuário
receber o resultado do offloading no próximo acesso à rede, mesmo que esse fique
desconectado por um longo período. A solução foi implementada em um testbed WiFi,
com acesso ao ambiente MCC utilizando cloudlet baseada na plataforma
OpenStack e integrada ao controlador SDN OpenDaylight. O consumo de energia
obtido pela proposta que utiliza SDN/OpenFlow para o gerenciamento de mobilidade
chegou a ser 11,33 vezes menor e a velocidade de processamento foi 3,23 vezes
maior que do ambiente tradicional. O sistema de caching remoto, apesar de se
mostrar útil em relação à rápida entrega dos resultados já processados, elevou
consideravelmente o consumo de energia da bateria. A técnica de caching remoto é
indicada para os casos nos quais a aplicação envia à cloudlet um grande volume de
dados para ser processado e o nível da bateria do dispositivo encontra-se em estado
não crítico ou quando o usuário enfrenta um longo período sem comunicação com a
cloudlet. / Although the great technological evolution in the mobile devices hardware and
wireless networks, remains significant limitations of these devices regarding
processing, storage, and energy, when compared to desktops and servers. The
paradigm of Mobile Cloud Computing (MCC) allows to extend the computational
resources of the mobile devices through the use of computational offloading
techniques, achieving a better performance on the part of the applications and a
reduction in the battery consumption of the devices. The offloading technique does
not always bring benefits to a mobile device in situations of high mobility since each
network change requires the execution of the offloading process. This dissertation
proposes a solution to optimize energy consumption and response times during the
computational offloading operations when the device change of access points (AP).
To this end, the proposal considers for such, a mobility management scheme based
on SDN (Software Defined Networking) and a remote caching technique, that allows
the user to receive the result from offloading in the next AP, even if he stays
disconnected for an extended period. The solution was implemented in one Wi-Fi
testbed, with access to the MCC environment using cloudlet based on the
OpenStack platform and integrated with the OpenDaylight SDN controller. The
achieved reduction of energy consumption for the mobility management proposal
arrived to be 11.33 times lower, and the processing speed was 3.23 times bigger that
of the traditional environment. The remote caching system, although useful in fast
delivering the already processed results, considerably raised the battery energy
consumption. Thus, the applicability of remote caching limits it to the cases where the
application sends to the cloudlet an enormous volume of data to be processed and
the battery level of the device is not critical or when the user faces an extended
period without communication with the cloudlet.
|
495 |
Um serviço para anonimização em redes definidas por softwareBomfim, Leonardo Henrique da Silva 22 February 2017 (has links)
This work has the goal to make an implementation of an anonymization service on
Software-Defined Networks (SDN) with the goal to reduce the number of attacks. With an
anonymization service is possible to hide the IP address from the network’s hosts, ensuring
more protection against security attacks, which allows a more time availability. One of the
biggest challenge on SDN architecture is the security issue. The separation of control and
data planes allows o generated challenges on security, due to the network’s permissiveness
to attacks such as “ Man in the Middle ”, Denial of Service and Saturation. The service
developed in this work, named as BomIP, uses the micro-data anonymization technique of
randomization of IP address of the hosts. The BomIP was added in the SDN controller
RunOS, which was the responsible to make the management of the real and anonymized
IP address. To validate this service it was developed two Case Studies with an environment
simulating a Denial of Service attack. The first Case Study made a comparison between
Crypto-Pan and BomIP. While the second Case Study made a comparison between a
traditional network IP and a SDN one using BomIP, both under Denial of Service attack.
The analysis of results showed that the service developed has an running time 65% more
efficient than Crypto-Pan. The assintotic analysis shows that BomIP is an algorith with
running time of quadratic order. The results also showed that the anonymized packets
can be tracked and a mitigation of 80% from the attacks trials, ensuring that the services
provided by the network remain available. / Este trabalho tem como objetivo implementar um servi¸co de anonimiza¸c˜ao em Redes
Definidas por Software (SDN) com o objetivo de realizar a mitiga¸c˜ao de tentativas de
ataque sofridas por uma rede. Atrav´es de um servi¸co de anonimiza¸c˜ao ´e poss´ıvel realizar a
oculta¸c˜ao dos endere¸cos IP dos hosts da rede, garantindo maior prote¸c˜ao contra ataques
`a seguran¸ca, permitindo um aumento de sua disponibilidade. Um dos maiores desafios
da arquitetura SDN ´e a seguran¸ca. A separa¸c˜ao do controle e do plano de dados permite
que desafios para garantir a seguran¸ca sejam gerados, devido `a permissividade da rede
a ataques como “Homem no Meio”, Nega¸c˜ao de Servi¸co e Satura¸c˜ao. O servi¸co aqui
desenvolvido, denominado de BomIP, utiliza a t´ecnica de anonimiza¸c˜ao de micro-dados
atrav´es da randomiza¸c˜ao dos endere¸cos IP dos hosts. O servi¸co BomIP foi adicionado ao
controlador RunOS, que ficou respons´avel por realizar o gerenciamento dos endere¸cos IP
reais e anonimizados. Para validar este servi¸co foram realizados dois Estudos de Caso
em um ambiente simulando um ataque de Nega¸c˜ao de Servi¸co. O primeiro Estudo de
Caso realizou a compara¸c˜ao do funcionamento do servi¸co de anonimiza¸c˜ao Crypto-Pan
com o BomIP. Enquanto que o segundo Estudo de Caso realizou a compara¸c˜ao de uma
rede IP tradicional sob ataque de Nega¸c˜ao de Servi¸co e uma SDN utilizando o BomIP.
A an´alise dos resultados mostrou que o servi¸co desenvolvido tem um tempo de execu¸c˜ao
65% mais eficiente que o Crypto-Pan. A an´alise de complexidade do algoritmo do BomIP
demonstrou que ´e de ordem quadr´atica. Os resultados tamb´em demonstraram que os
pacotes anonimizados permitem a rastreabilidade e a mitiga¸c˜ao de 80% das tentativas de
ataque, dando garantias que os servi¸cos providos pela rede continuem dispon´ıveis.
|
496 |
Radios cognitivos : implemetnação de uma plataforma multiagentes / A multiagent framework for cognitive radioPortelinha, Francisco Martins 01 December 2007 (has links)
Orientador: Luiz Carlos Kretly / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-08T18:48:25Z (GMT). No. of bitstreams: 1
Portelinha_FranciscoMartins_D.pdf: 24786076 bytes, checksum: 9371c9850eefc768ce24e777299b0788 (MD5)
Previous issue date: 2007 / Resumo: Em freqüênciasabaixode 3 GHz, ocorreuma demandade bandas no espectrode freqüência, devido à expansãodas redes de comunicaçõessem fio, principalmentepara aplicações outdoor. Estudosmostram que há grandes lacunas no espectrode freqüência até a faixa de 3 GHz. O modelo de alocação do espetrode freqüência,já ultrapassado, precisa ser reformuladopara uso destas lacunas.A utilização do espectro deve sair do modelo estático,para o modelodinâmico.Rádioscognitivose redes de rádios cognitivos surgem como opção tecnológica para uso deste novo modelo. Apresentamos uma arquitetura inovadorapara a implementaçãode rádios cognitivos,baseadosnos modelos computacionais de: rádios definidos por software,agentes e frameworks.Um estudo de caso, para rádio cognitivo nível 2, é apresentado para uso não licenciado no espectro nas faixas licenciadas para TV. Um algoritmo inovador, para detecção da disponibilidade de canais, é desenvolvido utilizando redes neurais / Abstract: In frequencies lower than 3 GHz, a demand occurs out of the frequency spectrum due to the expansion of the wireless communication network, mainly for outdoor applications. Studies show that, there are great gaps of the frequency spectrum in the bands up to 3 GHz. The allocation model of the frequency spectrum needs reformulatiQn for the use of these gaps. This utilization must come from, the change of a static model to a dynamic one. Cognitive radio and cognitive radio networks rise as a technological option for the use of the new model. We introduce and an innovatory architecture for the implementation of cognitive radios, based on the computational models of: software defined radio, agents and frameworks. A case study, for cognitive radio leveI 2, is introduced for use in licensed TV bands. A new algorithm is developed to detect available channel / Doutorado / Telecomunicações e Telemática / Doutor em Engenharia Elétrica
|
497 |
Gap filler adaptativo para sistema ISDB-TbRocha, Chrystianne 07 August 2014 (has links)
Made available in DSpace on 2016-03-15T19:37:50Z (GMT). No. of bitstreams: 1
Chrystianne Rocha.pdf: 2924776 bytes, checksum: a1d74db138a8b87f0518f3a6ef67c404 (MD5)
Previous issue date: 2014-08-07 / This master thesis presents the proposal of assigning the cognitive ability to a gap filler. Differently from the usual repeaters found on the market, the adaptive gap
filler is able to automatically monitor tuned channels with the intention of verifying if the protection ratio described in Resolution nº398 from Anatel is being respected. Spectrum sensing techniques and the concepts related to coverage area will be addressed. Tests were carried out on the Matlab and GNU Radio Software with the purpose of analyzing the adaptive
gap filler performance on real channels. / Este trabalho apresenta a proposta de atribuir ao gap filler a capacidade cognitiva . Diferentemente dos repetidores encontrados no mercado, o gap filler adaptativo tem como função monitorar, de forma autônoma, os canais sintonizados para verificar se a relação de proteção descrita na Resolução nº 398 da Anatel está sendo respeitada. Como fundamentos dessa proposta são abordadas as técnicas de sensoriamento do espectro e os conceitos relacionados às áreas de cobertura. Em uma abordagem prática, os testes foram desenvolvidos no Matlab e no GNU Radio, em que se analisa a atuação do gap filler adaptativo em canais reais.
|
498 |
Modulador 1-seg para SBTVD usando GNU RadioMaciel, Yuri Pontes 06 February 2015 (has links)
Made available in DSpace on 2016-03-15T19:37:55Z (GMT). No. of bitstreams: 1
YURI PONTES MACIEL.pdf: 3993729 bytes, checksum: a06d968ea944e726fa6263339ad70976 (MD5)
Previous issue date: 2015-02-06 / This paper describes by theoretical conceptualization and pratical experiences two relevant themes of electrical engineering and communications: software defined radio and the Brazilian digital television standard. This paper develops a specific modulator aimed to the portable reception of this digital television system, many times denominated as oneseg reception, by means of computational algorithms developed in the C++ programming language. These algorithms are executed in a development environment named GNU Radio, a open-source tool. Computer simulations are made to prove the correct behaviour of the project. Finnaly the modulator is implemented by means of a development kit of software defined radio then chained to a real communication system, thus proving its
practical operation. It is also possible to verify the versatility of the software defined radio, changing the modulator parameters in a fast and easy fashion. / Este trabalho aborda por meio de conceituação teórica e experiências práticas dois temas relevantes da engenharia elétrica e de comunicações: rádios definidos por software e
o padrão de televisão digital usado no Brasil. Este trabalho desenvolve um modulador específico para recepção portátil deste sistema de televisão digital, muitas vezes chamada
de recepção one-seg, por meio da elaboração de algoritmos computacionais feitos na linguagem de programação C++. Estes algoritmos por sua vez são executados em um
ambiente de desenvolvimento chamado GNU Radio, uma ferramenta do tipo open-source. Simulações computacionais são feitas de modo a comprovar o funcionamento do projeto.
Finalmente o modulador é implementado em um kit de desenvolvimento de rádio definido por software e então encadeado em um sistema de comunicação real, assim comprovando o seu funcionamento prático. É possível também verificar a versatilidade do rádio definido por software, alterando as configurações do modulador de maneira rápida e prática.
|
499 |
Balanceamento de carga utilizando planos de dados OpenFlow comerciaisCosta, Leonardo Chinelate 10 June 2016 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-07-28T11:35:35Z
No. of bitstreams: 1
leonardochinelatecosta.pdf: 971542 bytes, checksum: f5371f63a0629a94b6f8569205597bb5 (MD5) / Rejected by Adriana Oliveira (adriana.oliveira@ufjf.edu.br), reason: Corrigir openflow conforme consta no resumo OpenFlow on 2016-07-28T12:15:24Z (GMT) / Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-07-28T12:23:04Z
No. of bitstreams: 1
leonardochinelatecosta.pdf: 971542 bytes, checksum: f5371f63a0629a94b6f8569205597bb5 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-07-28T12:26:34Z (GMT) No. of bitstreams: 1
leonardochinelatecosta.pdf: 971542 bytes, checksum: f5371f63a0629a94b6f8569205597bb5 (MD5) / Made available in DSpace on 2016-07-28T12:26:34Z (GMT). No. of bitstreams: 1
leonardochinelatecosta.pdf: 971542 bytes, checksum: f5371f63a0629a94b6f8569205597bb5 (MD5)
Previous issue date: 2016-06-10 / O paradigmade Redes Definidas por Software (SDN) vem mudando a forma como gerenciar e operar redes de computadores através da sua principal ideia, a separação dos planos de dados e de controle. O protocolo OpenFlow implementa este conceito e,devido às vantagens de menor custo de operação e maior facilidade de adaptação a projetos de comutadores já existentes, é encontrado hoje em diversos equipamentos de rede comercializados por muitas empresas. Com o uso do paradigma SDN e do protocolo OpenFlow, a inovação e a evolução da rede são facilitadas. Dessa forma, muitos serviços típicos de rede podem ser repensados, de forma a torná-los mais flexíveis. Um desses serviços é o balanceamento de carga. Neste trabalho é realizado um estudo sobre a viabilidade de se implementar um balanceador de carga OpenFlow em uma rede SDN real, considerando as restrições existentes nos equipamentos OpenFlow comerciais atuais. Para isso, foi proposto um modelo de balanceamento de carga em SDN que leva em consideração diferentes perfis de carga mais realistas e que é baseado na utilização de diferentes políticas para a realização do balanceamento. Contudo, antes de reproduzir esse cenário em um ambiente real, foi realizada uma avaliação de desempenho de alguns planos de dados OpenFlow a fim de se verificar se as implementações OpenFlow atuais são capazes de suportar o balanceamento de carga ou outros serviços e uma rede de produção. Foi avaliada a qualidade de diferentes implementações OpenFlow de hardware switches comerciais e de implementações open source de software switches, através de métricas de desempenho em operações típicas de um switch OpenFlow. Os resultados mostram que as implementações OpenFlow dos hardware switches avaliados ainda não atingiram um nível de maturidade suficiente para serem utilizadas em larga escala. Apesar de desempenhos similares entre os modos OpenFlow e legacy na maioria dos casos, as implementações OpenFlow em hardware apresentaram problemas como implementações incompletas do padrão, baixo número de regras suportadas, funcionamento instável para tabelas de fluxo cheias e problemas no processamento de múltiplos comandos. / Software Defined Networks paradigm (SDN) is changing the way how we manage and operate computer networks by its main idea, the decoupling of data and control planes. OpenFlow protocol implements this concept and, due to the advantages of lower operating expenditures and greater ease of adaptation to existing switches projects, it is found today in various network equipment sold by many companies. Using SDN paradigm and OpenFlow protocol, network innovation and evolution are facilitated. Thus, many typical network services can be rethought in order to make them more flexible. An example of such services is load balancing. This work is a study about the feasibility of implementing an OpenFlow load balancer in a real SDN network, considering the restrictions in current commercial OpenFlow equipment. For this, we propose a SDN load balancing which considersdifferentmorerealisticworkloadprofilesandisbasedonusingdifferentpoliciesfor performing the balancing. However, before reproducing this scenario in a real environment, a performance evaluation of some OpenFlow data planes was conducted in order to verify that the current OpenFlow implementations are able to support load balancing or other services in production networks. The quality of different commercial OpenFlow hardware switch implementations and open source software switch implementations was evaluated, using performance metrics in typical operations of an OpenFlow switch. The results show that OpenFlow implementations of the evaluated hardware switches have not yet reached a sufficient level of maturity to be used on a large scale. Despite similar performances between OpenFlow and legacy modes in most cases, OpenFlow hardware implementations have presented problems such as standard incomplete implementations, low number of supported rules, unstable operation for full flow tables and problems in processing multiple commands
|
500 |
Adaptive router bypass techniques to enhance core network efficiencyGhonaim, Fahad A. 30 April 2018 (has links)
Internet traffic is increasing exponentially, driven by new technologies such as Internet of Things (IoT) and rich streaming media. The traditional IP router becomes a bottleneck for further Internet expansion due to its high power consumption and inefficiency in processing the growing traffic. Router bypass has been introduced to overcome capacity limitations and the processing costs of IP routers. With router bypass, a portion of traffic is provisioned to bypass the router and is switched by the transport layer. Router bypass has shown to provide significant savings in network costs. These advantages are limited by a reduction in the statistical multiplexing associated with the subdivision of the available bandwidth typically into bypass and traditional portions thus limiting the interest in bypass techniques.
This thesis will explore multiple techniques to enhance the efficiency of router bypass. The main goals are to address the issue of the reduction in statistical multiplexing and to add a dynamic approach to the router bypass mechanism. The recent advancements in the Optical Transport Network (OTN) play a major role in the transport network. This proposal takes full advantage of OTN in the router-bypassing context by applying recent developments such as Hitless Adjustments ODUflex (HAO), which
allow the provisioned channels to be adjusted without re-establishing the connections.
In addition, it will allow the bypassing mechanism to be flexible enough to meet the traffic behaviour needs of the future. This thesis will study multiple approaches to enhance the router bypass mechanism including: an adaptive provisioning style using various degrees of provisioning granularities and controlling the provisioning based on traffic behaviour. In addition, this thesis will explore the impact of automation in Software-Defined Networking (SDN) on router bypass. The application-driven infrastructure in SDN is moving the network to be more adaptive, which paves the way for an enhanced implementation of router bypass. Many challenges still face the industry to fully integrate the three layers (3, 2, and 1) to transform the current infrastructure into an adaptive application driven network. The IP router (layer 3) provisions and restores the connection regardless of the underlying layers (layer 2 and 1) and the transport layer does the same regardless of the IP layer. Although allowing every layer to develop without being constrained by other layers offers a huge advantage, it renders the transport layer static and not fully aware of the traffic behaviour. It is my hope that this thesis is a step forward in transforming the current network into a dynamic, efficient and responsive network. A simulation has been built to imitate the router bypassing concept and then many measurements have been recorded. / Graduate
|
Page generated in 0.0296 seconds