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The presence of a dead node in a distributed system
Ecler, Tomáš ; Škorpil, Vladislav (referee) ; Kenyeres, Martin (advisor)
This thesis deals with the distributed systems and the algorithms executed in these systems. The first part provides the theory relating to the mentioned topic as well as the mathematical tools used to model the functionality of a distributed system in which a dead node is present. The practical part is focused on an analysis of the impact of a dead node presence on the behavior of the Push-sum protocol. The simulations were executed on a tree, a ring, a star and a fully-connected mesh topology in Matlab.
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Impact of stochastic link failures on push-sum protocol
Ecler, Tomáš ; Škorpil, Vladislav (referee) ; Kenyeres, Martin (advisor)
This master’s thesis deals with the distributed computing and mathematical tools for modelling the distributed systems. Firstly, my attention is focused on a description of the distributed algorithms, characteristic failures for the distributed systems, and mathematical tools for an analysis of the distributed systems.The experimental part is concerned with the impact of stochastic link failures on the chosen parameters of the protocol Push-sum, namely the deviation of the final states from the average value, the convergence rate of the protocol, the distribution of the final states, and the distribution of the convergence rates. My intention is demonstrated using Matlab on a tree, a ring, a line, a star, and a fully-connected mesh topology. Was analyzed two functionalities of the protocol Push-sum, namely an estimation of the average value and an estimation of sum.
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Preventing attacks 802.11
Štefanec, Filip ; Kenyeres, Martin (referee) ; Novotný, Bohumil (advisor)
The main focus of this bachelor's thesis is on issues with security in wireless networks, based on standard 802.11. It includes description of most used encryption process and authentication methods in 802.11 networks. Also it explains functionality of EAP and RADIUS protocols, which are the main part of WPA/WPA2-Enterprise security mode. At the end of the thesis there is simulation of basic attacks on standard 802.11 and consequently desing and implementation of security, which prevents similar attacks. Implementation of security is based on authentication of clients through RADIUS server.
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Analysis and Improvement of Distributed Systems
Kenyeres, Martin ; Sýkora, Jiří (referee) ; Klučik,, Stanislav (referee) ; Škorpil, Vladislav (advisor)
A significant progress in the evolution of the computer systems and their interconnection over the past 70 years has allowed replacing the frequently used centralized architectures with the highly distributed ones, formed by independent entities fulfilling specific functionalities as one user-intransparent unit. This has resulted in an intense scientic interest in distributed algorithms and their frequent implementation into real systems. Especially, distributed algorithms for multi-sensor data fusion, ensuring an enhanced QoS of executed applications, find a wide usage. This doctoral thesis addresses an optimization and an analysis of the distributed systems, namely the distributed consensus-based algorithms for an aggregate function estimation (primarily, my attention is focused on a mean estimation). The first section is concerned with a theoretical background of the distributed systems, their evolution, their architectures, and a comparison with the centralized systems (i.e. their advantages/disadvantages). The second chapter deals with multi-sensor data fusion, its application, the classification of the distributed estimation techniques, their mathematical modeling, and frequently quoted algorithms for distributed averaging (e.g. protocol Push-Sum, Metropolis-Hastings weights, Best Constant weights etc.). The practical part is focused on mechanisms for an optimization of the distributed systems, the proposal of novel algorithms and complements for the distributed systems, their analysis, and comparative studies in terms of such as the convergence rate, the estimation precision, the robustness, the applicability to real systems etc.
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Impact of stochastic link failures on push-sum protocol
Ecler, Tomáš ; Škorpil, Vladislav (referee) ; Kenyeres, Martin (advisor)
This master’s thesis deals with the distributed computing and mathematical tools for modelling the distributed systems. Firstly, my attention is focused on a description of the distributed algorithms, characteristic failures for the distributed systems, and mathematical tools for an analysis of the distributed systems.The experimental part is concerned with the impact of stochastic link failures on the chosen parameters of the protocol Push-sum, namely the deviation of the final states from the average value, the convergence rate of the protocol, the distribution of the final states, and the distribution of the convergence rates. My intention is demonstrated using Matlab on a tree, a ring, a line, a star, and a fully-connected mesh topology. Was analyzed two functionalities of the protocol Push-sum, namely an estimation of the average value and an estimation of sum.
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