Orientador: Mauricio Ferreira Magalhães / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-17T10:39:34Z (GMT). No. of bitstreams: 1 EsteveRothenberg_ChristianRodolfo_D.pdf: 14213626 bytes, checksum: 46a6a812d056a078c8a7fe49c80ce0ff (MD5) Previous issue date: 2010 / Resumo: Esta tese introduz um novo conceito para as redes de conteúdo denominado compact forwarding. Este conceito traduz-se na utilização de técnicas probabilísticas no plano de encaminhamento onde o espaço de identificação não é mais relacionado a um host final, mas sim, à identificação de conteúdo(s). A essência do conceito originou-se de uma questão básica, qual seja, onde deve ser colocado o estado associado ao encaminhamento do pacote? Nos elementos de rede ou no cabeçalho do pacote? A tese propõe duas soluções que representam estes extremos, SPSwitch, na qual o estado é colocado nos elementos de rede e, LIPSIN, onde o estado é colocado no cabeçalho do pacote. O denominador comum a essas soluções consiste na utilização de técnicas probabilísticas inspiradas no Bloom filter como elemento base das decisões de encaminhamento. A utilização de estruturas de dados derivadas do Bloom filter traz um custo adicional necessário à minimização dos erros associados à utilização de uma estrutura probabilística. A tese contribui com várias técnicas para redução desses erros incluindo a análise dos custos associados. Cenários de aplicação são apresentados para validação das propostas discutidas no trabalho / Abstract: This thesis introduces the concept of compact forwarding in the field of content-oriented networks. The main idea behind this concept is taking a probabilistic approach to the problem of packet forwarding in networks centered on content identifiers rather than traditional host addresses. The fundamental question explored is where to place the packet forwarding state, in network nodes or in packet headers? Solutions for both extremes are proposed. In the SPSwitch, approximate forwarding state is kept in network nodes. In LIPSIN, the state is carried in the packets themselves. Both approaches are based on probabilistic packet forwarding functions inspired by the Bloom filter data structure. The approximate forwarding state comes at the cost of additional considerations due to the effects of one-sided error-prone data structures. The thesis contributes with a series of techniques to mitigate the false positive errors. The proposed compact forwarding methods are experimentally validated in several practical networking scenarios / Doutorado / Engenharia de Computação / Doutor em Engenharia Elétrica

Det här arbetet handlar om en mjukvara vars mål är att tillhandahålla syntaxträning inom routeradministration inriktad mot målgruppen studenter. Mjukvaran har programmerats från grunden i programmeringsspråket Python och är menad att erbjuda ett simplistiskt användargränsnitt. Programmeringen har resulterat i ett program som döpts till Routersyntax och består av två delar: ett klientprogram och ett serverprogram. Både klientprogrammet och serverprogrammet går att installera och köra i flera olika operativsystemmiljöer, med främsta fokus på Windows, Ubuntu Linux och OS X. Det är simplistiskt utformat, enkelt att installera och köra, samt gratis att använda för studenter. Förhoppningen är att användaren med hjälp av syntaxträningsmjukvaran ska få en chans att träna sina färdigheter i att skriva routerkommandon för användning av studenter i universitetskurser. / This report explains the implementation and purpose for the computer software called Routersyntax that aims to assist students in exercising router command syntax. Written in Python, the software uses a simplistic command line-driven user interface, designed specifically for routing administration training. The software is divided into two parts: a client and a server. Using the router syntax software, users get an opportunity to try to improve their skills in administering router hardware by exercising router command input in an environment which is free to use for students. The aim is for the software to require nothing but Python and a Python-compatible operating system to run. It supports Windows, Ubuntu Linux and OS X out of the box.

FPGAs are frequently used in network systems to provide the performance and flexibility that is required of modern computer networks while allowing network vendors to bring products to market quickly. Like all electronic devices, FPGAs are vulnerable to ionizing radiation which can cause applications operating on an FPGA to fail. These low-level failures can have a wide range of negative effects on the performance of a network system. As computer networks play a larger role in modern society, it becomes increasingly important that these soft errors are addressed in the design of network systems.This work presents a framework for testing the soft-error reliability of FPGA-based networking systems. The framework consists of the NetFPGA development board, a custom traffic generator, and a custom high-speed JTAG configuration device. The NetFPGA development board is versatile and can be used to implement a wide range of network applications. The traffic generator is used to exercise the network system on the NetFPGA and to determine the health of that system. The JTAG configuration device is used to manage reliability experiments, to perform fault injection into the FPGA, and to monitor the NetFPGA during radiation tests.This thesis includes soft-error reliability tests that were performed on an Ethernet switch network system. Using both fault injection and accelerate radiation testing, the soft error sensitivity of the Ethernet switch was measured. The Ethernet switch design was then mitigated using triple module redundancy and duplication with compare. These mitigated designs were also tested and compared against the baseline design. Radiation testing shows that TMR provides a 5.05x improvement in reliability over the baseline design. DWC provides a 5.22x improvement in detectability over the baseline design without reducing the reliability of the system.

Information and communication technology (ICT) greatly influence today’s business processes be it in public or private sectors. Everything that is done in business requires ICT in one way or the other. Research in ICTs is therefore critical. So much research was and is still carried out in projects that develop or enhance ICT but it is still apparent that the success rate of these projects is still very low. The extensive coverage of ICTs implies that if the success rate is still that low, many resources are being wasted in the failed projects; therefore, more research is needed to improve the success rate. Previous research has focussed on factors which are critical for the success of ICT projects, assuming that all ICT projects are the same. As a result, literature is full of different suggestions and guidelines of the factors critical to ICT projects’ success. This scenario brings challenges to project managers who end up using their own personal judgement to select which factors to consider for any project at hand. The end result is the high failure rate of ICT projects since there is a very high chance of applying the same critical success factors to different types of ICT projects. This research answered the question: which factors are critical to the success of computer networking projects in Zimbabwe and how these factors could be used for building a model that determines in advance the success of such projects? Literature reviewed indicated that most CSFs were not focused on specific types of ICT projects, hence were generalised. No literature was found on ICT projects’ CSFs in Zimbabwe. More so, no CSFs were found for computer networking projects as a specific instance of ICT projects. No model existed that predicts computer networking projects’ success. This study addressed the gaps by developing a CSF framework for ICT projects in Zimbabwe, determining CSFs for computer networking projects in Zimbabwe and the development of a logistic regression analysis model to predict computer networking projects’ success in Zimbabwe. Data was collected in Zimbabwe using a unique three-staged process which comprise metasynthesis analysis, questionnaire and interviews. The study was motivated by the fact that most available research focused on CSFs for general ICT projects and that no research was found on CSFs influencing projects in computer networking. Meta-synthesis analysis was therefore conducted on literature in order to identify CSFs as given in literature. The approach was appropriate since the researcher had noticed that there were extensive ICT projects’ CSFs and that no such research has been carried out in Zimbabwe. These CSFs formed the basis for the determination (using a questionnaire) of ICT projects CSFs for Zimbabwe in particular. Project practitioners’ viewpoints were sought through questionnaires. Once CSFs for ICT projects in Zimbabwe were determined, they formed the basis for the determination of unique critical success factors for computer networking projects in Zimbabwe. Interviews were used to get further information that would have been left out by questionnaires. The interview questions were set to clarify some unclear or conflicting responses from the questionnaire and providing in-depth insights into the factors critical to computer networking projects in Zimbabwe. The data i.e. critical success factors for computer networking projects guided the development of the logistic regression analysis model for the prediction of computer networking projects’ success in Zimbabwe. Data analysis from the questionnaire was analysed using SPSS Version 23.0. Factor analysis and principal component analysis were some of the techniques used in the analysis. Interview data was analysed through NVivo Version 10.0. From the results it was deduced that factors critical to ICT project management in Zimbabwe were closely related to those found in the literature. The only apparent difference was that CSFs for ICT projects in Zimbabwe were more specific thereby enhancing their applicability. Computer networking projects had fewer CSFs than general ICT projects. In addition, CSFs for general ICT projects were different from those critical to computer networking projects in Zimbabwe. The development of a comprehensive set of general ICT projects’ CSFs was the first contribution of this study. This was achieved through meta-synthesis analysis. The other contribution was the development of a CSF framework for ICT projects specific to Zimbabwe and those specific to computer networking projects in Zimbabwe. The major contribution was the development of the logistic regression analysis model that predicts computer networking projects’ success in Zimbabwe. These contributions will provide literature on ICT project management in Zimbabwe which will subsequently assist ICT project managers to concentrate on specific factors. The developed prediction model can be used by project managers to determine possible success or failure of ICT projects; thereby possible reducing wastage of resource. / School of Computing

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Computer modeling and simulation is a practical way to design and test a system without actually having to build it. Simulation has many benefits which apply to many different domains: it reduces costs creating different prototypes for mechanical engineers, increases the safety of chemical engineers exposed to dangerous chemicals, speeds up the time to model physical reactions, and trains soldiers to prepare for battle. The motivation behind this work is to build a common software framework that can be used to create new networking simulators on top of an HLA-based federation for distributed simulation. The goals are to model and simulate networking architectures and protocols by developing a common underlying simulation infrastructure and to reduce the time a developer has to learn the semantics of message passing and time management to free more time for experimentation and data collection and reporting. This is accomplished by evolving the simulation engine through three different applications that model three different types of network protocols. Computer networking is a good candidate for simulation because of the Internet's rapid growth that has spawned off the need for new protocols and algorithms and the desire for a common infrastructure to model these protocols and algorithms. One simulation, the 3DInterconnect simulator, simulates data transmitting through a hardware k-array n-cube network interconnect. Performance results show that k-array n-cube topologies can sustain higher traffic load than the currently used interconnects. The second simulator, Cluster Leader Logic Algorithm Simulator, simulates an ad-hoc wireless routing protocol that uses a data distribution methodology based on the GPS-QHRA routing protocol. CLL algorithm can realize a maximum of 45% power savings and maximum 25% reduced queuing delay compared to GPS-QHRA. The third simulator simulates a grid resource discovery protocol for helping Virtual Organizations to find resource on a grid network to compute or store data on. Results show that worst-case 99.43% of the discovery messages are able to find a resource provider to use for computation. The simulation engine was then built to perform basic HLA operations. Results show successful HLA functions including creating, joining, and resigning from a federation, time management, and event publication and subscription.

This research is an investigation of the potential means to make the Information Systems (IS) course more accessible to Walter Sisulu University (WSU) students. As some IS students at this institution are unable to attend classes on a regular basis, this study aims to establish if and how the WSU Accounting Department (which offers the IS course) could use e-Iearning to support the teaching, learning and assessment of IS. This qualitative study was approached from an interpretive perspective. The study has undergone one cycle of an action research approach. The methods used in the study include surveys, an expert review and focus group interviews. The data was elicited from participants using questionnaires and an interview schedule. A staff questionnaire was used to elicit information from IS staff from four contact universities in South Africa to determine their experience of using Information and Communication Technology (ICT) for e-learning in an IS course. A student questionnaire was used to determine the WSU IS students' reasons for absenteeism, their learning needs, and their current computer access and skills. Data from both of these surveys informed the development of the WSU IS pilot website. An expert review questionnaire ascertained the subject expert's opinions about the newly developed WSU IS pilot website. The website was found to be of good quality with respect to the four aspects that Harvey and Green (J 993 cited in Lomas 2002) use to define quality. Some modifications were made to the WSU IS pilot website as a result of the expert's comments. After the website was used by the IS students, two focus group interviews were conducted to determine the students' perceptions of the value of the website. The data was analyzed, interpreted and linked to the literature surveyed. The main findings indicate that the WSU IS pilot website could be part of a more globalised higher education offering than the paper-based IS course offered before. However, the staff and the student surveys revealed that ICT has opened the gap in equity at the higher education institutions, highlighting that access to a university does not mean equal access to lectures and computers. The WSU IS pilot website endeavoured to capitalise on students' physical access to computers by supporting epistemological access to the curriculum, by encouraging them to exercise control over their learning. This study has ideally enabled the Accounting Department to deliver its services to students and this in turn will hopefully help WSU retain its part-time students and improve the student pass rates.

Multihoming allows nodes to be multiply connected to the network. It forms the basis of features which can improve network responsiveness and robustness; e.g. load balancing and fail-over, which can be considered as a choice between network locations. However, IP today assumes that IP addresses specify both network location and node identity. Therefore, these features must be implemented at routers. This dissertation considers an alternative based on the multihoming approach of the Identifier Locator Network Protocol (ILNP). ILNP is one of many proposals for a split between network location and node identity. However, unlike other proposals, ILNP removes the use of IP addresses as they are used today. To date, ILNP has not been implemented within an operating system stack. I produce the first implementation of ILNP in FreeBSD, based on a superset of IPv6 – ILNPv6 – and demonstrate a key feature of ILNP: multihoming as a first class function of the operating system, rather than being implemented as a routing function as it is today. To evaluate the multihoming capability, I demonstrate one important application of multihoming – load distribution – at three levels of network hierarchy including individual hosts, a singleton Site Border Router (SBR), and a novel, dynamically instantiated, distributed SBR (dSBR). For each level, I present empirical results from a hardware testbed; metrics include latency, throughput, loss and reordering. I compare performance with unmodified IPv6 and NPTv6. Finally, I evaluate the feasibility of dSBR-ILNPv6 as an alternative to existing multihoming approaches, based on measurements of the dSBR's responsiveness to changes in site connectivity. We find that multihoming can be implemented by individual hosts and/or SBRs, without requiring additional routing state as is the case today, and without any significant additional load or overhead compared to unicast IPv6.