by Fu Chengpeng. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (p. 102-119). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

In 3GPP Release 5 and beyond, an All-IP architecture has been specified. This indicates that convergence of mobile applications such as voice, video and gaming to IP is not a "trend" anymore, but a reality. IP mobility has therefore been intensively studied in recent years. Majority of the existing IP mobility schemes, including Mobile IPv6 (MIPv6), the current de facto standard solution for IP mobility, are designed around a two-tier addressing model. In this model, while visiting a foreign link, a mobile node (MN) is identified by its home address assigned by its home link but is located by the care-of-address (CoA) acquired from the foreign link. Incoming packets for the MN are routed to its home link as usual, but are intercepted by the home agent and tunneled to the CoA. This model is simple and is well accepted. However, when it comes to real-time applications, it also has been known to be ineffective in terms of handoff delay and bandwidth consumption due to, respectively, its lengthy CoA acquisition and the extra IP header for tunneling. The latter is especially expensive for the case of real-time applications because of the excessive overhead induced by the extra IP header (20 bytes for IPv4 and 40 bytes for IPv6) to the packet payload size (∼20-160 bytes). / In this thesis, we show that (i) can be overcome when a direct Layer-3 connection between the home and any particular visiting domain is available so that inter-domain routing effectively becomes routing within the same logical hierarchy. We call a global network formed by the directly Layer-3 connected domains the Global Universal Addressing (GUA) framework. When deployed on the GUA framework, the existing local mobility schemes can easily be upgraded to support global mobility as seamlessly as local mobility with no modification needed. / Much work has been devoted to improving the two-tier addressing model, including various local mobility schemes such as HAWAII and Cellular IP. These schemes eliminate the CoA acquisition when the MNs move within one domain, but revert back to the two-tier addressing model when the mobility is across different domains (or so-called global mobility). These schemes therefore inherit all the drawbacks of the two-tier addressing model when it comes to global mobility. It has been argued that mobility across domains is rare. However, looking into the near future, this assumption is certainly not applicable to the upcoming fourth-generation (4G) wireless architecture in which the MNs can dynamically choose the best connected wireless interface among heterogeneous networks (e.g., WiFi, WiMax, etc.) of different domains as they move. Therefore, an efficient solution is needed to handle the frequent inter-domain mobility, or global mobility, in the form of heterogeneous handoffs as well. / To address (ii), we propose a new IP mobility scheme called Cellular Universal IP (CUIP), which runs on the GUA framework and makes use of a home route concept also proposed in this thesis. The home route concept intelligently integrates the efficiency of prefix routing and flexibility of full-address routing to achieve high performance and routing scalability under the universal addressing model. In addition, based on IPv6, CUIP makes use of the IPv6 option header to embed the route-update information of an MN in the outgoing data packets for a short period after handoff, so that global routing information can be effectively updated along the path traversed by the packets. We study the performance of CUIP quantitatively and show the following: (1) the average number of routers updated per handoff is less than three, so that the average handoff delay is minimal. (2) The routing table complexity is asymptotically independent of the depth and monotonically decreasing with the width of the network hierarchy. That is, routing scalability is not a concern even in large networks. / To efficiently support global mobility, a universal addressing model, under which a mobile node is always identified and located by the same IP address globally, is an obvious answer to the problems associated with the two-tier addressing model. However, the universal addressing model has been considered to be infeasible due to difficulties in (i) inter-domain (or cross-prefix) IP routing and (ii) routing table scaling. / by Lam, Pak Kit. / "June 2007." / Adviser: Soung Liew. / Source: Dissertation Abstracts International, Volume: 69-01, Section: B, page: 0553. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 128-130). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Um dos obstáculos para o uso disseminado do multicast na Internet global é o desenvolvimento de protocolos de controle de congestionamento adequados. Um fator que contribui para este problema é a heterogeneidade de equipamentos, enlaces e condições de acesso dos receptores, a qual aumenta a complexidade de implementação e validação destes protocolos. Devido ao multicast poder envolver milhares de receptores simultaneamente, o desafio deste tipo de protocolo se torna ainda maior, pois além das questões relacionadas ao congestionamento da rede, é necessário considerar fatores como sincronismo, controle de feedbacks, equidade de tráfego, entre outros. Por esses motivos, os protocolos de controle de congestionamento multicast têm sido um tópico de intensa pesquisa nos últimos anos. Uma das alternativas para o controle de congestionamento multicast na Internet é o protocolo ALMTF (Adaptive Layered Multicast TCP-Friendly), o qual faz parte do projeto SAM (Sistema Adaptativo Multimídia). Uma vantagem desse algoritmo é inferir o nível de congestionamento da rede, determinando a taxa de recebimento mais apropriada para cada receptor. Além disso, ele realiza o controle da banda recebida, visando à justiça e a imparcialidade com os demais tráfegos concorrentes. O ALMTF foi desenvolvido originalmente em uma Tese de doutorado e teve a sua validação no simulador de redes NS-2 (Network Simulator). Este trabalho tem como objetivo estender o protocolo para uma rede real, implementando, validando os seus mecanismos e propondo novas alternativas que o adaptem para esse ambiente. Além disso, efetuar a comparação dos resultados reais com a simulação, identificando as diferenças e promovendo as pesquisas experimentais na área. / One of the obstacles for the widespread use of the multicast in the global Internet is the development of adequate protocols for congestion control. One factor that contributes for this problem is the heterogeneity of equipments, enlaces and conditions of access of the receivers, which increases the implementation and validation complexity of these protocols. Due to the number (thousands) of receivers simultaneously involved in multicast, the challenge of these protocols is even higher. Besides the issues related to the network congestion, it is necessary to consider factors such as synchronism, feedback control, fairness, among others. For these reasons, the multicast congestion control protocols have been a topic of intense research in recent years. The ALMTF protocol (Adaptive Layered Multicast TCP-Friendly), which is part of project SAM, is one of the alternatives for the multicast congestion control in the Internet. One advantage of this algorithm is its ability to infer the network congestion level, assigning the best receiving rate for each receptor. Besides that, the protocol manages the received rate, aiming to achieve fairness and impartiality with the competing network traffic. The ALMTF was developed originally in a Ph.D. Thesis and had its validation under NS-2 simulator. The goal this work is to extend the protocol ALMTF for a real network, validating its mechanisms and considering new alternatives to adapt it for this environment. Moreover, to make the comparison of the real results with the simulation, being identified the differences and promoting the experimental research in the area.

A área de gerência de rede cresce à medida que redes mais seguras e menos vulneráveis são necessárias, e as aplicações que concorrem pelo seu uso, necessitam de alta disponibilidade e qualidade de serviço. Quando estamos focando a gerência da infra-estrutura física das redes de computadores, por exemplo, a taxa de uso de um segmento de rede, podemos dizer que esse tipo de gerenciamento encontra-se em um patamar bastante sedimentado e testado. Por outro lado, há ainda lacunas para pesquisar na área de gerenciamento de protocolos de alto nível. Entender o comportamento da rede como um todo, conhecer quais hosts mais se comunicam, quais aplicações geram mais tráfego e, baseado nessas estatísticas, gerar uma política para a distribuição de recursos levando em consideração as aplicações críticas é um dever nas redes atuais. O grupo de trabalho IETF RMON padronizou, em 1997, a MIB RMON2. Ela foi criada para permitir a monitoração de protocolos das camadas superiores (rede, transporte e aplicação), a qual é uma boa alternativa para realizar as tarefas de gerenciamento recém mencionadas. Outro problema para os gerentes de rede é a proliferação dos protocolos de alto nível e aplicações corporativas distribuídas. Devido a crescente quantidade de protocolos e aplicações sendo executados sobre as redes de computadores, os softwares de gerenciamento necessitam ser adaptados para serem capazes de gerenciá-los. Isso, atualmente, não é fácil porque é necessário usar linguagens de programação de baixo nível ou atualizar o firmware dos equipamentos de monitoração, como ocorre com os probes RMON2. Considerando este contexto, esse trabalho propõe o desenvolvimento de um agente RMON2 que contemple alguns grupos dessa MIB. O agente baseia-se na monitoração protocolos de alto nível e aplicações que são executados sobre o IP (Internet Protocol) e Ethernet (na camada de enlace). Além da implementação do agente, o trabalho apresenta um estudo de como obter estatísticas do agente RMON2 e usá-las efetivamente para gerenciar protocolos de alto nível e aplicações.

Dissertação (Mestrado em Engenharia Elétrica) - Centro Universitário da FEI, São Bernardo do Campo, 2014

Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 2008

Tese de mestrado. Redes e Serviços de Comunicação. Faculdade de Engenharia. Universidade do Porto. 2006

Dissertação apresentada para obtenção do grau de Mestre em Redes e Serviços de Comunicação, na Faculdade de Engenharia da Universidade do Porto, sob a orientação do Professor Doutor Raúl Filipe Teixeira Oliveira

Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores (Major Telecomunicações). Faculdade de Engenharia. Universidade do Porto. 2009

Estágio realizado na PT Inovação / Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 2008