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Optimalization and analysis of communication services latency dependencies
Zikmund, Lukáš ; Škorpil, Vladislav (referee) ; Endrle, Pavel (advisor)
This master’s thesis is focused on ensuring of Quality of Service (QoS) in wireless network for standards IEEE 802.11 a/b/g/n. First part of this thesis is focused on the theory of this issue. It covers methods of data transfer in computer networks and individual transfer parameters especially on parameters needed to ensure quality of service. It also describes standards for wireless data transmission and protocols for real time data transmission. The second part is devoted to OPNET modeler and to simulations created on this program. Simulations are focused on real-time data transfer and compare the standards in terms of delay and jitter.
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Methods for the measurement of bit rates in data networks
Franc, Jan ; Martinásek, Zdeněk (referee) ; Zeman, Václav (advisor)
The target of this master's thesis were the known methods for testing the quality of transfer parameters of data networks. I have studied the RFC 2544 document to analyze these tests. From that information and by studying other existing web-based applications I was able to design a concept of my own application that will allow to measure basic quality parameters of transfers made through the Internet (the parameters: downstream, upstream, latency, variance of these and a traced route). My application doesn't require any modifications on the user's system. It's built on the server-based programming language PHP and uses the relational database engine MySQL to store measurement and user data. On the client side, it's assisted by the JavaScript scripting language. Both registered users and visitors are allowed to perform the listed measurements. Registered users are able to browse the history of their own benchmark results and also to send messages to others. There is an administrative account to oversee the operations. Another part of my thesis work is an application for Windows that performs the same measurements but does not use JavaScript.
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Methods for measurement of data network performance and quality parameters
Sukup, Luboš ; Zeman, Václav (referee) ; Novotný, Vít (advisor)
Master thesis involves the development of quality measurement issues and performance parameters in data networks. It describes the main technologies as they affect the quality and performance parameters and the effect of these parameters for voice, video and data services. Next are listed some methods for measuring parameters of the data network.In the practical part is selected one method of measuring network parameters and properties of this method are demonstrated by illustrative examples.
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Host distance measurement using ICMP protocol in IP networks
Fojtová, Lucie ; Komosný, Dan (referee) ; Burget, Radim (advisor)
Current internet more and more often faces the problem of the right definition of distance between the single hosts. The knowledge of this quantity influences the areas of the optimal lay-out of overlay multicast networks, the right selection of peer-to-peer network participant, or the simple decision of the end user: which one of the nearest mirrors to use for downloading datas. The nearest one doesn't have to mean the nearest in geographical point of view - the distance on Internet is usually expressed by quantities as latency or bandwidth. All these examples have got the saving of bandwidth in common and therefore economical saving. The methods of host position prediction in networks work on the basis of measuring latency parameter. The tools for measuring of this parameter will be set up in this thesis and at the same time it will be shown how geographical distance and latency correspond with each other.
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Performing a Relay Attack on Mifare Smart Cards
Činčala, Martin ; Henzl, Martin (referee) ; Malčík, Dominik (advisor)
This thesis deals with performing a relay attack on MIFARE smartcards while using off-the-shelf readers only. These readers are not designed for such attacks therefore implementation of the attack that would succeed against every smartcard was not possible. Since various attacks on smartcards have already been implemented, I have focused on the latest and still insufficiently explored card MIFARE Ultralight C. Relay attack has been implemented with simplified emulation of 4-bytes long UID and successfully tested on MIFARE Ultralight C. With the use of other readers it should be possible to perform attack also on other cards like MIFARE Plus, Desfire and SmartMX. For the purpose of cloning MIFARE Classic open-source tools are introduced.
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Wireless communication link analyzer
Dostálek, Jakub ; Burian, František (referee) ; Jílek, Tomáš (advisor)
The aim of this bachelor thesis is to design and implement a wireless communication analyzer in mobile robotics, using IPv4 protocol and Ethernet interface and to create correctly selected and expressed characteristics from the measured data, according to which the wireless communication channel can be further optimized for the best data transmission. To meet these requirements, a brief search of existing solutions was performed, their applicability was discussed and important parameters of the wireless transmission channel were defined, which will form the given characteristics. Furthermore, the actual design and implementation of a wireless communication link analyzer for previously specified required parameters, verification of its functionality on the transmission link with known parameters and automation of measurement and data evaluation was performed.
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Geolocation in Internet using latency measurements
Harth, Petr ; Balej, Jiří (referee) ; Komosný, Dan (advisor)
This diploma thesis is concerned with practical realization of CBG (Constraint-based Geolocation) algorithm, which is one of the IP (Internet Protocol) geolocation technique. IP geolocation determines the localization of a computer workstation location on the basis of on its IP address. The factors causing delays in data transfer are discussed first, followed by discussion of the issue of measuring these delays. The detailed explanation of IP geolocation follows where its contexts as well as the active geolocation techniques (techniques based on delay measurement mentioned above) are described. After that a brief description of PlanetLab experimental network, which was used for geolocation techniques measuring, is presented followed by a section explaining the creation of reference points and targets, which are another necessary prerequisite for practical realization of the method. Then the practical realization is explained in the form of CBGfinder program and its verification on the basis of artificial input data along with an actual example of IP geolocation of a point in the Internet are provided. Last but not least the measurement results of CBG algorithm are introduced, based on the analysis of Bestline parameters of one of the PlanetLab nodes measured in the period of one month, followed by a discussion of the inaccuracy of geological position and the computation speed. The cumulative distribution function as well as the kernel density estimation are also described. Final part of the thesis consists of discussion on measured results compared to results of other geological techniques results implemented by colleagues of the author of this diploma thesis. The results are compared on the basis of average inaccuracy of geological position estimations and its median, computation time, cumulative distribution function and kernel density estimation are also taken into regard.
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Estimation of the IP station location based on the parameters of network traffic
Ripper, David ; Komosný, Dan (referee) ; Verner, Lukáš (advisor)
This bachelor’s thesis covers the topic of evaluation of the geographical location of stations on the Internet with the help of measurements of the delay and implementation of the CBG method, which embodies both theoretical and practical parts of the bachelor’s thesis. The first part of this thesis is dedicated to passive geolocation methods, types of delays in data network, and their subsequent measurement. The second part pursues active geolocation methods, specifically the CBG method. Aim was to program a localization algorithm in the programming language PHP, subsequently evaluate accuracy of the method and compare with available methods IP geolocation.
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Localization of IP stations based on model of probability delay measurement
Tropp, Peter ; Komosný, Dan (referee) ; Verner, Lukáš (advisor)
The master thesis is dealing with Internet host localization methods, more exactly with determining geographical position of the unknown Internet host connected to the network using RTT delay measuring. The first part is dealing with description of RTT delays that may occur in the network and tools for their measurement. The next is part of thesis is devoted to description of two kinds of localization methods. Ones that are using existing data to determine the position of Internet host also called passive methods, and others that are using RTT delay measurement, also called active methods. The main part is focused on GeoWeight method which is based on geographical localization estimation of Internet host. It is based on RTT delay measurement using the principles of CBG method, enhanced by introduction of the theory of weights according to the probability of the target Internet host. The last part is describing the application that was made to determine the geographic localization of the target Internet host using GeoWeight method. The application was afterwards tested by measuring RTT delay in PlanetLab experimental network. At the end the final measured results were compared with other localization methods (CBG, Octant, SOI, GeoIP).
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Semi-automated Design of High-performance Digital Circuits with Xilinx FPGAs
Houška, David ; Dvořák, Vojtěch (referee) ; Šťáva, Martin (advisor)
Tato diplomová práce se zabývá návrhem sekvenčních digitálních obvodů s ohledem na optimalizaci zpoždění. V práci je popsána problematika dvou technik, které jsou běžně používané při optimalizaci – stručně je popsána technika tzv. synchronizace registrů (angl. retiming), větší pozornost je však věnována technice tzv. zřetězení (angl. pipelining). V rámci praktické části byla vypracována forma abstrakce sekvenčních digitálních obvodů pomocí acyklických orientovaných grafů. Obvod je tak přenesen do roviny, ve které je jednodušší jej transformovat. Zároveň je představen nástroj pro polo-automatickou optimalizaci digitálních obvodů vyvíjených v prostředí Xilinx ISE Design Suite využitím techniky zřetězení.
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