Orientador: Nelson Luis Saldanha da Fonseca / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-13T10:39:46Z (GMT). No. of bitstreams: 1 Augusto_LeonardoRangel_M.pdf: 852383 bytes, checksum: f25ba2736c185851498448650c0aef68 (MD5) Previous issue date: 2006 / Resumo: A classe de Serviço Assegurado da arquitetura de Serviços Diferenciados (DiffServ) da Internet inclui a provisão de diferenciação de banda passante, o que depende do adequado USG de mecanismos de condicionamento de tráfego e gerenciamento ativo de filas (AQM). Nesta dissertação, propõe-se um controlador ótimo para gerenciamento ativo de filas para a arquitetura Diffserv. Seu projeto considera intrinsecamente a influência de fluxos não adaptativos na dinâmica do controle de congestionamento. Apesar de o controlador obtido ser racional, seu projeto utiliza uma abordagem não-racional, o que aumenta a precisão do modelo. Simulações conduzidas demonstram que o controlador proposto reduz o descarte desnecessário de pacotes, aumentando o goodput e diminuindo a quantidade de RTOs dos emissores TCP. / Abstract: The Assured Service of Differentiated Services Arehitecture (DiffServ) is currently used for providing throughput differentiation in the Internet. For this, traffic policing and active queue management (AQM) mechanisms must be used. In this dissertation, we use a non-rational approach to develop an optimal AQM controller. Its design considers both adaptative and non-adaptative like UDP. Simulations were conducted for comparison with other proposals. Results show that the proposed controller reduces unnecessary packet drops, increases the goodput and reduces the TCP sender's Retransmission Timeouts. / Mestrado / Redes de Computadores / Mestre em Ciência da Computação

Submitted by Patrícia Cerveira (pcerveira1@gmail.com) on 2017-06-13T15:41:09Z No. of bitstreams: 1 Marcelo Dissertação.pdf: 13477166 bytes, checksum: e46f91138593316f4c2c1504aaf297a3 (MD5) / Rejected by Biblioteca da Escola de Engenharia (bee@ndc.uff.br), reason: Boa tarde, Patrícia! Favor acertar o resumo. Atenciosamente, Catarina Ribeiro Bibliotecária BEE - Ramal 5992 on 2017-06-29T16:10:33Z (GMT) / Submitted by Patrícia Cerveira (pcerveira1@gmail.com) on 2017-06-29T19:26:55Z No. of bitstreams: 1 Marcelo Dissertação.pdf: 13477166 bytes, checksum: e46f91138593316f4c2c1504aaf297a3 (MD5) / Approved for entry into archive by Biblioteca da Escola de Engenharia (bee@ndc.uff.br) on 2017-07-03T12:53:35Z (GMT) No. of bitstreams: 1 Marcelo Dissertação.pdf: 13477166 bytes, checksum: e46f91138593316f4c2c1504aaf297a3 (MD5) / Made available in DSpace on 2017-07-03T12:53:35Z (GMT). No. of bitstreams: 1 Marcelo Dissertação.pdf: 13477166 bytes, checksum: e46f91138593316f4c2c1504aaf297a3 (MD5) / O serviço ”Móvel de Voz sobre IP” é a convergência natural da tecnologia de voz sobre IP (VoIP) e a comunicação sem fio, e pode impulsionar o aumento da popularidade da primeira bem como promover constantes avanços da última. Embora seja possível encontrar várias aplicações que oferecem serviço de VoIP na Internet e muitos dispositivos que implementam VoIP em hardware, uma implementação aberta e não-proprietária pode ser integrada aos serviços legados - como PABXs institucionais - o que proporciona uma contribuição significativa. Este trabalho descreve a implementação do serviço Móvel de Voz sobre IP no Instituto Federal Fluminense e destaca os desafios a serem enfrentados em seu gerenciamento e operação, enfatizando a segurança contra ataques. Os principais resultados indicam que este serviço oferece flexibilidade, conforto, redução de custos e mobilidade para o serviço de voz. / A “Mobile Voice over IP” service is the natural convergence of Voice over IP (VoIP) technology and wireless communication, and can leverage the increading popularity of the former and the constant advances of the latter. Although we can find various applications that o er VoIP service on the Internet, and in e ect many devices that implement VoIP in hardware, an open, non-propietary implementation that can be integrated with legacy services such as institutional PABXs is a welcome addition. This works describes the implementation of the Mobile Voice over IP service in the Instituto Federal Fluminense, and the challenges of its management and operation, with emphasis in security against attacks. This services brings flexibility, confort, cost reduction and mobility to the voice service.

På några år har användningen av IP-telefoni inom svenska företag tredubblats och vi börjar nu se ett attitydskifte gentemot en teknik som länge dragits med dåligt rykte på grund av kvalitetsbrister. IP-telefoni är ett resultat av att data- och telefonikommunikation vävs samman och att kapaciteten i nätverken ökar. Detta medför att man genom att införa IP-telefoni kan genomföra kostnadsbesparingar och effektivisering. Men tekniken erbjuder även ökad funktionalitet och därmed även mervärde för organisationer som använder IP-telefoni. Inser organisationer detta och utnyttjar man fördelarna med tekniken för att skapa acceptans inom organisationen? Syftet är att undersöka vilka faktorer som motiverar en övergång från kretskopplad telefoni till IP-telefoni, och hur man inom en organisation skapar acceptans för den nya tekniken. Syftet har uppfyllts genom en kvalitativ studie som byggt på semi-standardiserade intervjuer. Studien genomfördes hos fyra svenska organisationer som implementerat en ”ren” IP-telefonilösning med IP-växel och hårdvarutelefoner. Resultatet av studien visar att det är vanligt att utnyttja en större händelse som startskott för implementationen. Detta kan röra sig om en flytt eller en renovering av organisationens lokaler. De främsta orsakerna till att man väljer IP-telefoni har visat sig vara kostnadsbesparingar, effektivisering av nätverksinfrastrukturen samt att man ser tekniken som en investering för framtiden. Det har visat sig att de företag som genomfört en grundlig studie av IP-telefoni som teknik, inledningsvis har identifierat fler fördelar med tekniken. Vidare har studien även visat att organisationer upplever ett initialt motstånd till förändringen från anställda och att detta motstånd ofta uppkommer i anknytning till tekniska problem som uppstår i samband med implementationen. Det är mycket ovanligt att organisationer har en speciell fas för att skapa acceptans för förändringen, vilket troligtvis beror på att man ser användandet som liknande med traditionell PSTN-telefoni och att resurser istället läggs på att lösa tekniska problem. / Over the last few years there has been a threefold increase in the use of IP telephony within Swedish companies. We are now beginning to see a change in attitude towards a technology that thanks to poor Quality of Service has been struggling with a bad reputation. IP telephony is a result of computer and telephone networks being con-verged, and by doing this, costs can be saved and efficiency boosted. But the technology does also offer increased functionality and thereby added value to the organisations using it. But do organisations realize this, and do they exploit the benefits of the technology in order to create acceptance for it within the organisation? The purpose is to examine what the motivating factors are for a transition from PSTN telephony to IP telephony, and also to study how acceptance for the new technology is created within the organisation. The purpose has been fulfilled by conducting a qualitative study based on semi-standardized interviews. The study has been conducted at four Swedish organisations that have implemented a "pure" IP telephony solution including IP gateways and IP telephones. The result of the study shows that it is common to use a "big event" as a starting block for the implementation. This could be a relocation or the restoration of an office building. The main reason for choosing IP telephony is the fact that convergence cuts costs, boosts efficiency, and that organisations see IP telephony as an investment for the future. We have noticed that organisations that conduct a thorough study of IP telephony have identified more functional advantages with the technology. Furthermore, the study has shown that organisations experience initial resistance from users, and that this resistance often arises in connection to technical problems that transpire during the implementation. It is rare for organisations to have special phase for creation of acceptance, which most likely is due to the fact that organisations see the use of IP telephony as similar to the use of traditional PSTN telephony, and that resources instead are being placed on solving technical problems

Examensarbetet är en studie i felsökning och optimering av IP-telefonisystem i ett befintligt nät. Här beskrivs hur ett IP-telefoninät bör byggas och konfigureras för optimal prestanda utifrån Ciscos rekommendationer. Det aktuella nätet är IT-Partners nät som drivs av Nortel när det gäller IP-telefonidelen. I dagsläget har de vissa återkommande problem när det gäller IP-telefonin t.ex. att samtalet bryts då och då. Det är nämnt vad problemet kan vara och vilka lösningar som skulle passa nätet. I allmänt brister kunskaperna i IP-telefoni vilket medför att problem kan uppstå med att få ett IP-telefonisystem att fungera som det ska. Vidare berättas varför ett IP-telefonisystem inte optimeras redan från första stadiet.

The Global Navigation Satellite System (GNSS), in the last few years, has been supporting the development of mobile telephony and the expansion of electronic equipments (GNSS receivers) to promote a revolution in geodetic surveys in real time. In this context, it becomes important the technique of positioning Real Time Kinematic (RTK) with the use of differential corrections transmitted by the protocol named Networked Transport of RTCM via the Internet Protocol (NTRIP), from a reference station via Internet. It is aimed, in this research, the evaluation of the precision of this technique for different lengths of baseline, and also the use of different numbers of trace periods. Then, three-dimensional coordinates of 10 stations (DEM) were used, they were also located in three municipalities of Rio Grande do Sul, which were traced by the static post-processed (static PP) method, which helped as being a reference in comparison with technique RTK / NTRIP, that used the correlations of the Brazilian Network for Continuous Monitoring of the GNSS Systems in real time - (RBMC-IP). The results showed that there was resolution of the ambiguities in nine seasons at baseline greater than 54 km, and that the precision values showed no difference greater than 0.041 m in the horizontal component and 0.083 m in the vertical component. In addition, between the numbers of the tested periods (5,10,30, 60 and 120 periods) for the method RTK / NTRIP, the tested period that had the best average precision of the horizontal component was the 120 one (0.01 m), and for the vertical component was considered the five periods number as the most appropriated (0.02 m). Hence, it was proved the reliability of the technique RTK / NTRIP (RBMC-IP) in baselines of until 54 km, showing that it can be used for topographical surveys in areas with wireless Internet or cellular services such as GPRS, GSM and 3G. / O Sistema Global de Navegação por Satélite (GNSS) nos últimos anos vem se apoiando no desenvolvimento da telefonia móvel e no avanço da eletrônica dos equipamentos (receptores GNSS) para promover uma revolução nos levantamentos geodésicos em tempo real. Neste contexto, se destaca a técnica de posicionamento Real Time Kinematic (RTK) usando correções diferenciais transmitidas pelo protocolo Networked Transport of RTCM via internet Protocol (NTRIP), a partir de uma estação de referência via internet. O objetivo deste trabalho foi avaliar a precisão desta técnica para diferentes comprimentos de linha de base e com o uso de diferentes números de épocas de rastreio. Para isso, foram utilizadas as coordenadas tridimensionais de 10 estações (marcos), localizadas em três municípios do estado do Rio Grande do Sul, rastreadas pelo método relativo estático pós-processado (estático PP), o qual serviu de referência na comparação com a técnica RTK / NTRIP, que utilizou de correções da Rede Brasileira de Monitoramento contínuo dos Sistemas GNSS em tempo real (RBMC-IP). Os resultados mostraram que houve resolução das ambiguidades em nove estações numa linha de base superior a 54 km e que os valores de acurácia não apresentaram diferença superior a 0,041 m na componente horizontal e 0,083 m na componente vertical. Além disso, entre os números de épocas testados (5, 10, 30, 60 e 120 épocas) para o método RTK / NTRIP, aquele que apresentou a melhor média de acurácia horizontal foi o de 120 épocas (0,01 m) e para a componente vertical o melhor resultado foi alcançado com o número de 5 épocas rastreadas (0,02 m). Deste modo, foi comprovada a confiabilidade da técnica RTK / NTRIP (RBMC-IP) em linhas de base de até 54 km, podendo ser utilizada para levantamentos topográficos em locais providos por Internet wireless ou serviços de telefonia celular tais como, GPRS, GSM e 3G.

Avec le développement des applications temps-réel sur Internet, telles que la télévision, la voix sur IP et les jeux en ligne, les fournisseurs d'accès à Internet doivent faire face à des contraintes de plus en plus fortes quant aux performances de leurs services. Cependant, après chaque changement topologique, les protocoles de routage à état des liens, utilisés dans les réseaux de cœur de ces opérateurs, entrent dans une période de convergence durant laquelle des boucles de routage peuvent apparaître. Ce phénomène dégrade les performances du réseau (latence, congestions, pertes de paquets) et peut durer plusieurs secondes. Dans le cadre de cette thèse, nous proposons de nouvelles solutions permettant de prévenir ces perturbations dans le cas de reconfigurations sur un lien ou un routeur. Notre approche a pour particularité de ne reposer que sur les mécanismes de base des protocoles de routage à état des liens, et d’être ainsi déployable de manière incrémentale dans n’importe quel réseau. Intuitivement, il s’agit de contrôler implicitement l’ordre de mise à jour des routeurs, à travers une modification progressive du poids d’un sous-ensemble de liens. Par exemple, l’augmentation du poids d’un lien aura pour effet de forcer les routeurs les plus éloignés de ce composant à se mettre à jour avant les routeurs plus proches. En adaptant finement l’amplitude de tels changements, il est alors possible de répartir la mise à jour de routeurs potentiellement impliqués dans une boucle sur plusieurs étapes. Cette opération peut ensuite être répétée jusqu’à ce que le composant ne soit plus utilisé pour acheminer des données dans le réseau, permettant un retrait sans impact sur le routage. / The use of real time media or mission critical applications over IP networks is making strong pressure on service providers to operate disruption free networks. However, after any topological change, link-state Interior Gateway Protocols (IGPs), such as IS-IS or OSPF, enter a convergence phase during which transient forwarding loops may occur. Such loops increase the network latency and cause packet losses for several seconds. In this thesis, we propose and evaluate innovative solutions to prevent these perturbations in case a planned modification on a link or a router. Our approach only relies on core functionalities of link-state routing protocols, thus being incrementally deployable in any network. Intuitively, it consists in implicitly controlling the routers update order through successive IGP weight reconfigurations on a subset of links. For example, progressively increasing the weight of a link forces farthest routers to update their routes first, before closest ones. Hence, finely tuning such changes may allow to spread the update of routers potentially implied in a loop across multiple steps. This operation can be repeated until the component to be removed is no longer used to forward traffic in the network, thus allowing its removal with no impact on the routing decisions.

Orientador: Varese Salvador Timóteo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Tecnologia / Made available in DSpace on 2018-08-24T04:02:34Z (GMT). No. of bitstreams: 1 Diorio_RafaelFernando_M.pdf: 6050961 bytes, checksum: bb3814ee43754ae271ad5e4eb3d704b7 (MD5) Previous issue date: 2013 / Resumo: A presente dissertação contempla a implementação e validação funcional de um gateway multimídia baseado em IP a partir da implementação de recursos para classificação, rotulação, identificação e encaminhamento de fluxos de tráfego distintos (elástico e stream), ambos com modelagem de tráfego pré-definida, a partir de informações constantes no cabeçalho dos pacotes IP (campos ToS do IPv4 e TC do IPv6, tidos como DSCP [RFC 2474] e ECN [RFC 3168]) para os serviços multimídia de áudio, voz, vídeo e dados fornecidos por um emulador de tráfego multimídia baseado em IP. De modo complementar a tais implementações, o gateway multimídia também objetiva o fornecimento de recursos de qualidade de serviço (QoS) aos serviços por ele intermediados e que necessitem de tais recursos, tais como serviços multimídia de voz e vídeo, por exemplo. Os testes funcionais e de desempenho com o gateway multimídia, realizados em ambiente cabeado e sem fio, demonstram que sua implementação é válida e que não influência em modificações quanto ao perfil (características) dos tráfegos por ele intermediados, bem como à questões envolvendo erros, atrasos e variações de atrasos (jitter), dentre outras, demonstrando que sua implementação é transparente aos sistemas finais envolvidos no processo de comunicação intermediado por tal gateway multimídia. Seu ambiente de desenvolvimento e testes é baseado em soluções de software livre, fornecido, especialmente, pelo sistema operacional Linux e pela solução Netfilter/Iptables, disponibilizando uma plataforma aberta para o estudo e aprimoramento futuro quanto ao gateway multimídia. Por fim, espera-se que o gateway multimídia contribua como uma nova ferramenta para testes e análises de soluções voltadas às redes multimídia de modo geral / Abstract: This dissertation describes the implementation and functional validation of an IP-based multimedia gateway to the identification, classification and forwarding of different traffic flows (elastic and stream), both with pre-defined traffic profiles, from the ToS field of the IPv4 header and the TC field of the IPv6 header, taken as DSCP [RFC 2474] and ECN [RFC 3168]. The multimedia traffic corresponding to audio, voice, video and data services are provided by a multimedia traffic generator, which generates traffic according to given distributions. The multimedia gateway also aims at providing resources for quality of service (QoS) for services that require these resources, such as multimedia services for voice and video. The functional and performance testing with multimedia gateway, performed in a wired and wireless environment, demonstrates that its implementation is valid and not influence in changes in the traffic profile (characteristics) of the traffic intermediated by him, as well as issues involving errors, delays and variations in delay (jitter), among others, showing that its implementation is transparent to the end systems involved in the communication process intermediated by such multimedia gateway. It's development and testing environment is based on open source solutions, based on the Linux operating system and the Netfilter/Iptables solution, providing an open platform for future research and improvement of the multimedia gateway. Finally, it is expected that the multimedia gateway contributes as a new tool for testing and analysis of multimedia networks in general / Mestrado / Tecnologia e Inovação / Mestre em Tecnologia

Orientador: Celso de Almeida / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-26T13:55:04Z (GMT). No. of bitstreams: 1 Pilo-PaisAlbuja_PabloAndres_M.pdf: 1954449 bytes, checksum: e3d003c58a69987d3faeca15cf23928f (MD5) Previous issue date: 2015 / Resumo: Os enlaces sem fio são propensos a gerar mais erros e perdas de segmentos devido à natureza do desvanecimento neste canal de comunicação. A falta de um mecanismo no protocolo TCP Reno que permita distinguir as perdas por erros aleatórios das perdas por congestionamento, resulta na redução da vazão de dados e um desempenho inferior ao esperado. A fim de melhorar o desempenho do protocolo TCP sobre redes sem fio, uma variante do protocolo TCP que utiliza uma confirmação negativa, NACK, foi proposta previamente em [1] para informar ao transmissor acerca do recebimento de um segmento com erro para sua retransmissão instantânea sem reduzir a janela de congestionamento. Na presente dissertação será avaliado o desempenho do algoritmo TCP-NACK sobre um cenário de provas com desvanecimento Rayleigh. Os resultados mostram que o protocolo TCP-NACK possui melhor desempenho em relação ao protocolo TCP em enlaces sem fio / Abstract: Wireless links are prone to generate more errors and segments loss due to the fading nature of the communication channel. The lack of a mechanism in TCP Reno to distinguish random errors from congestion losses, results in throughput reduction and performance lower than expected. In order to improve TCP over wireless networks, a negative acknowledgment, NACK, was earlier proposed in [1] to inform the transmitter about the reception of a segment with error for its retransmission without reducing the congestion window. In this thesis we are going to evaluate the TCP-NACK algorithm over a scenario with Rayleigh fading. The results show that TCP-NACK has better performance over TCP Reno in wireless links / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica

Dissertation thesis deals with methods for finding the location of the device in the Internet, based on knowledge of the IP address. The process is called IP geolocation and is currently solved by geolocation databases or by measurement of network properties to the IP address. The disadvantage of nowadays geolocation databases is an incorrect information about some locations, because they can be in large distance from correct position. The aim of the thesis is to develop a method for verification of a position from geolocation database using delay measurement. Because of it, there is a detail analysis of influence of partial delays on the distance estimation accuracy, calculated using measured delay between the landmark and the target IP address. For the same reason, long-term delay measurement was performed, where the IP geolocation accuracy was compared using calibration data from previous measurements. On this background, Cable Length Based Geolocalisation (CLBG) method is proposed. Principle of this method is built on the properties of partial delays, which depend on the length of transport media. Firstly, the method measures round trip time (rtt), which is subsequently lowered by intermediate devices and end stations delay. The geographical distance is estimated using signal speed in the transport media. Further, the winding media parameter is established, which is used to determine a constraint around the landmark. The intersection of all constraints defines the area, where the target IP is. The IP geolocation using CLBG gives better results than simpler methods (ShortestPing, GeoPing and SOI), in comparison with more advanced methods (CBG and Octant) the accuracy is similar. The disadvantage of the CLBG method is the size of region, where the target lies, but this is due to its purpose. The position found in geolocation database can be checked by evaluation if it lies in the region.

The aim of the diploma thesis is to choose network simulator suitable for network technologies laboratory tasks for educational use. Theoretical part of thesis describes basics of network communication, addressing, reference models. Thesis also describes standards Wi Fi, Ethernet and routing protocol OSPF - technologies which are discussed in laboratory tasks. The practical part of diploma thesis describes a few available network simulators suitable for creating two laboratory tasks. Finally, the NS-3 simulator was chosen. Both laboratory tasks include theoretical introduction, detailed description of source code, individual tasks, expected outputs and control questions which senses understanding of discussed technologies.