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Dissertations / Theses on the topic 'Network topology'
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Oliveira, Olga Margarida Fajarda. "Network topology discovery." Doctoral thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/18692.
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Doutoramento em MatemáticaA monitorização e avaliação do desempenho de uma rede são essenciais para detetar e resolver falhas no seu funcionamento. De modo a conseguir efetuar essa monitorização, e essencial conhecer a topologia da rede, que muitas vezes e desconhecida. Muitas das técnicas usadas para a descoberta da topologia requerem a cooperação de todos os dispositivos de rede, o que devido a questões e políticas de segurança e quase impossível de acontecer. Torna-se assim necessário utilizar técnicas que recolham, passivamente e sem a cooperação de dispositivos intermédios, informação que permita a inferência da topologia da rede. Isto pode ser feito recorrendo a técnicas de tomografia, que usam medições extremo-a-extremo, tais como o atraso sofrido pelos pacotes. Nesta tese usamos métodos de programação linear inteira para resolver o problema de inferir uma topologia de rede usando apenas medições extremo-a-extremo. Apresentamos duas formulações compactas de programação linear inteira mista (MILP) para resolver o problema. Resultados computacionais mostraram que a medida que o número de dispositivos terminais cresce, o tempo que as duas formulações MILP compactas necessitam para resolver o problema, também cresce rapidamente. Consequentemente, elaborámos duas heurísticas com base nos métodos Feasibility Pump e Local ranching. Uma vez que as medidas de atraso têm erros associados, desenvolvemos duas abordagens robustas, um para controlar o número máximo de desvios e outra para reduzir o risco de custo alto. Criámos ainda um sistema que mede os atrasos de pacotes entre computadores de uma rede e apresenta a topologia dessa rede.
Monitoring and evaluating the performance of a network is essential to detect and resolve network failures. In order to achieve this monitoring level, it is essential to know the topology of the network which is often unknown. Many of the techniques used to discover the topology require the cooperation of all network devices, which is almost impossible due to security and policy issues. It is therefore, necessary to use techniques that collect, passively and without the cooperation of intermediate devices, the necessary information to allow the inference of the network topology. This can be done using tomography techniques, which use end-to-end measurements, such as the packet delays. In this thesis, we used some integer linear programming theory and methods to solve the problem of inferring a network topology using only end-to-end measurements. We present two compact mixed integer linear programming (MILP) formulations to solve the problem. Computational results showed that as the number of end-devices grows, the time need by the two compact MILP formulations to solve the problem also grows rapidly. Therefore, we elaborate two heuristics based on the Feasibility Pump and Local Branching method. Since the packet delay measurements have some errors associated, we developed two robust approaches, one to control the maximum number of deviations and the other to reduce the risk of high cost. We also created a system that measures the packet delays between computers on a network and displays the topology of that network.
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Norangshol, Roy Sindre. "Open network topology services." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for datateknikk og informasjonsvitenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-23100.
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This master project examines whether there is an existing model fordescribing network topologies in abstract and generic manner. I alsolooked for networking protocols for exchanging network topologiesand handling of dynamically creation of circuit connections acrossdomains. I?ve also been working on a prototype for visualization ofnetwork topologies using Network Administration Visualized (NAV)as a data backend, and further to check the possibilities to use thefound topology model in my prototype.My findings shows that there is progress towards creating a stan-dard topology model to describe network topologies in an abstractand generic manner. There is also progress in creating a network ar-chitecture with networking protocols for exchanging network topolo-gies across domains and providing a connection reservation service tohandle creation of dynamically circuit connections. Prototype showsthere is lots of ideas for further works on what to implement in re-gards of the found network topology model and networking systemsthat was found.
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Gu, Yuwei Ph D. Massachusetts Institute of Technology. "Controlling polymer network topology." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122851.
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Thesis: Ph. D. in Organic Chemistry, Massachusetts Institute of Technology, Department of Chemistry, 2019Cataloged from PDF version of thesis.
Includes bibliographical references.
Chapter 1: Introduction to Polymer Network Topology on a (Macro)Molecular Level Polymer network topology, comprising the ways in which strands and junctions are connected in polymer networks, plays a critical role in dictating many material properties. Here we discuss classical challenges in the field and review existing strategies to characterize and manipulate polymer network topology from a (macro)molecular level. Chapter 2: Semibatch Monomer Addition as a General Method to Tune and Enhance the Mechanics of Polymer Networks via Loop-defect Control In this chapter we introduce semibatch monomer addition as a general strategy to reduce/control an important topological feature at short length scale-primary loops, thus providing materials with tunable and significantly improved mechanical properties without changing their composition.
Chapter 3: Leaving Groups as Traceless Topological Modifiers for Controlling Topological Structure in Chemically Identical Polymer Networks Here we report "traceless topological modification" as a general approach to control an important long length-scale topological feature-junction distribution. Using self-assembled structures as templates that are not themselves incorporated into the network, our method enables us to synthesize truly topologically isomeric networks with drastically different macroscopic properties. Chapter 4: Photoswitching Topology in Polymer Networks with Metal-Organic Cages as Crosslinks Based on our works in Chapter 2 and Chapter 3, we further explored topology as the central design principle to create novel functional materials.
In this chapter we introduce topology switching via cooperative self-assembly as a design principle to reversibly alter multiple network properties simultaneously and enable the preparation of one material that can exist in multiple topological states. Chapter 5: Living Additive Manufacturing: Transformation of Parent Gels into Diversely Functionalized Daughter Gels Made Possible by Visible Light Photoredox Catalysis Our ability to control polymer network topology has been further enhanced by developing living additive manufacturing as an effective strategy to expand the original topology of parent networks in a photo-growth fashion. This approach enables us to transform the mechanical/physical properties of parent networks post-synthetically.
Chapter 6: polyMOF Nanoparticles: Dual Roles of a Multivalent polyMOF Ligand in Size Control and Surface Functionalization Here we present a novel approach to synthesizing well defined metal-organic framework nanoparticles (MOF NPs), where the size control and surface functionalization of MOF-5 NPs were simultaneously achieved using multivalent polyMOF ligands.
by Yuwei Gu.
Ph. D. in Organic Chemistry
Ph.D.inOrganicChemistry Massachusetts Institute of Technology, Department of Chemistry
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Fard, Pedram J. "Dynamic reconfiguration of network topology in optical networks." College Park, Md. : University of Maryland, 2007. http://hdl.handle.net/1903/7412.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2007.Thesis research directed by: Electrical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Yao, Ye. "Ad Hoc Networks Measurement Model and Methods Based on Network Tomography." Phd thesis, Université de Technologie de Belfort-Montbeliard, 2011. http://tel.archives-ouvertes.fr/tel-00636282.
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The measurability of Mobile ad hoc network (MANET) is the precondition of itsmanagement, performance optimization and network resources re-allocations. However, MANET is an infrastructure-free, multi-hop, andself-organized temporary network, comprised of a group of mobile nodes with wirelesscommunication devices. Not only does its topology structure vary with time going by, butalso the communication protocol used in its network layer or data link layer is diverse andnon-standard.In order to solve the problem of interior links performance (such as packet loss rate anddelay) measurement in MANET, this thesis has adopted an external measurement basedon network tomography (NT). To the best of our knowledge, NT technique is adaptable for Ad Hoc networkmeasurement.This thesis has deeply studied MANET measurement technique based on NT. The maincontributions are:(1) An analysis technique on MANET topology dynamic characteristic based onmobility model was proposed. At first, an Ad Hoc network mobility model formalizationis described. Then a MANET topology snapshots capturing method was proposed to findand verify that MANET topology varies in steady and non-steady state in turnperiodically. At the same time, it was proved that it was practicable in theory to introduceNT technique into Ad Hoc network measurement. The fitness hypothesis verification wasadopted to obtain the rule of Ad Hoc network topology dynamic characteristic parameters,and the Markov stochastic process was adopted to analyze MANET topology dynamiccharacteristic. The simulation results show that the method above not only is valid andgenerable to be used for all mobility models in NS-2 Tool, but also could obtain thetopology state keeping experimental formula and topology state varying probabilityformula.IV(2) An analysis technique for MANET topology dynamic characteristic based onmeasurement sample was proposed. When the scenario file of mobile models could notbe obtained beforehand, End-to-End measurement was used in MANET to obtain thepath delay time. Then topology steady period of MANET is inferred by judging whetherpath delay dithering is close to zero. At the same time, the MANET topology wasidentified by using hierarchical clustering method based on measurement sample of pathperformance during topology steady period in order to support the link performanceinference. The simulation result verified that the method above could not only detect themeasurement window time of MANET effectively, but also identify the MANETtopology architecture during measurement window time correctly.(3) A MANET link performance inference algorithm based on linear analysis modelwas proposed. The relation of inequality between link and path performance, such as lossrate of MANET, was deduced according to a linear model. The phenomena thatcommunication characteristic of packets, such as delay and loss rate, is more similarwhen the sub-paths has longer shared links was proved in the document. When the rankof the routing matrix is equal to that of its augmentation matrix, the linear model wasused to describe the Ad Hoc network link performance inference method. The simulationresults show that the algorithm not only is effective, but also has short computing time.(4) A Link performance inference algorithm based on multi-objectives optimizationwas proposed. When the rank of the routing matrix is not equal to that of its augmentationmatrix, the link performance inference was changed into multi-objectives optimizationand genetic algorithm is used to infer link performance. The probability distribution oflink performance in certain time t was obtained by performing more measurements andstatistically analyzing the hypo-solutions. Through the simulation, it can be safelyconcluded that the internal link performance, such as, link loss ratio and link delay, can beinferred correctly when the rank of the routing matrix is not equal to that of itsaugmentation matrix.
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Pfennig, Stefan, and Elke Franz. "Secure Network Coding: Dependency of Efficiency on Network Topology." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-128456.
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Network Coding is a new possibility to transmit data through a network. By combining different packets instead of simply forwarding, network coding offers the opportunity to reach the Min-Cut/Max-Flow capacity in multicast data transmissions. However, the basic schemes are vulnerable to so-called pollution attacks, where an attacker can jam large parts of the transmission by infiltrating only one bogus message. In the literature we found several approaches which aim at handling this kind of attack with different amounts of overhead. Though, the cost for a specific secure network coding scheme highly depends on the underlying network. The goal of this paper is on the one hand to describe which network parameters influence the efficiency of a certain scheme and on the other hand to provide concrete suggestions for selecting the most efficient secure network coding scheme considering a given network. We will illustrate that there does not exist “the best” secure network scheme concerning efficiency, but all selected schemes are more or less suited under certain network topologies.
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Khorramzadeh, Yasamin. "Network Reliability: Theory, Estimation, and Applications." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/64383.
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Network reliability is the probabilistic measure that determines whether a network remains functional when its elements fail at random. Definition of functionality varies depending on the problem of interest, thus network reliability has much potential as a unifying framework to study a broad range of problems arising in complex network contexts. However, since its introduction in the 1950's, network reliability has remained more of an interesting theoretical construct than a practical tool. In large part, this is due to well-established complexity costs for both its evaluation and approximation, which has led to the classification of network reliability as a NP-Hard problem. In this dissertation we present an algorithm to estimate network reliability and then utilize it to evaluate the reliability of large networks under various descriptions of functionality.
The primary goal of this dissertation is to pose network reliability as a general scheme that provides a practical and efficiently computable observable to distinguish different networks. Employing this concept, we are able to demonstrate how local structural changes can impose global consequences. We further use network reliability to assess the most critical network entities which ensure a network's reliability. We investigate each of these aspects of reliability by demonstrating some example applications.Ph. D.
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Jin, Xing. "Topology inference and tree construction for topology-aware overlay streaming /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?CSED%202007%20JIN.
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Long, Weili. "On the topology design of hose-model VPN networks /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?ECED%202008%20LONG.
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Deccio, Casey T. "Network-layer Selective Security." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd560.pdf.
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Sigholm, Johan. "Automated Network Node Discovery and Topology Analysis." Thesis, Linköping University, Department of Computer and Information Science, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-10593.
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This Master's Thesis describes the design and development of an architecture for automated network node discovery and topology analysis, implemented as an extension to the network management and provisioning system NETadmin. The architecture includes functionality for flexible network model assessment, using a method for versatile comparison between off-line database models and real-world models. These models are populated by current node data collected by network sensors.
The presented architecture supports (1) efficient creation and synchronization of network topology information (2) accurate recognition of new, replaced and upgraded nodes, including rogue nodes that may exhibit malicious behavior, and (3) provides an extension of an existing vendor-neutral enterprise network management and provisioning system.
An evaluation of the implementation shows evidence of accurate discovery and classification of unmatched hosts in a live customer production network with over 400 nodes, and presents data on performance and scalability levels.
The work was carried out at Netadmin System i Sverige AB, in Linköping, Sweden.
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Dong, Yu-An 1974. "Statistical analysis of protein interaction network topology." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28925.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, February 2005.Includes bibliographical references (leaves 116-117).
Complex networks arise in diverse areas of natural and social sciences and network topology is a key determinant of such systems. In this work we investigate the protein-protein interaction network of the KSHV herpesvirus, which is the first viral system available, and compare it to a prototypical cellular system. On the local level, we investigated the relationship between interaction and sequence evolution, functional class, phylogenetic class, and expression profiles. On the global level, we focused on large-scale properties like small-world, scale-free, and attack tolerance. Major differences were discovered between viral and cellular systems, and we were able to pinpoint directions for further investigation, both theoretically and experimentally. New approaches to discover functional associations through interaction patterns were also presented and validated. To put the KSHV network in the context of host interactions, we were able to predict interactions between KSHV and human proteins and use them to connect the KSHV and human PPI networks. Though simulations, we show that the combined viral-host network is distinct from and superior to equivalent randomly combined networks. Our combined network provides the first-draft of a viral-host system, which is crucial to understanding viral pathogenicity. In a separate chapter, the results of a project combining experiments and bioinformatics are also presented. We were able to report [approximately]30 new yeast protein-protein interactions and pinpoint the biological significance of some of those interactions. The methodology of yeast two-hybrid itself is also tested and assessed.
by Yu-An Dong.
Ph.D.
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Loe, Chuan. "On the topology Of network fine structures." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/28624.
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Multi-relational dynamics are ubiquitous in many complex systems like transportations, social and biological. This thesis studies the two mathematical objects that encapsulate these relationships --- multiplexes and interval graphs. The former is the modern outlook in Network Science to generalize the edges in graphs while the latter was popularized during the 1960s in Graph Theory. Although multiplexes and interval graphs are nearly 50 years apart, their motivations are similar and it is worthwhile to investigate their structural connections and properties. This thesis look into these mathematical objects and presents their connections. For example we will look at the community structures in multiplexes and learn how unstable the detection algorithms are. This can lead researchers to the wrong conclusions. Thus it is important to get formalism precise and this thesis shows that the complexity of interval graphs is an indicator to the precision. However this measure of complexity is a computational hard problem in Graph Theory and in turn we use a heuristic strategy from Network Science to tackle the problem. One of the main contributions of this thesis is the compilation of the disparate literature on these mathematical objects. The novelty of this contribution is in using the statistical tools from population biology to deduce the completeness of this thesis's bibliography. It can also be used as a framework for researchers to quantify the comprehensiveness of their preliminary investigations. From the large body of multiplex research, the thesis focuses on the statistical properties of the projection of multiplexes (the reduction of multi-relational system to a single relationship network). It is important as projection is always used as the baseline for many relevant algorithms and its topology is insightful to understand the dynamics of the system.
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Saal, Oliver. "Visualisation of ATM network connectivity and topology." Master's thesis, University of Cape Town, 2001. http://hdl.handle.net/11427/6437.
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Bibliography: leaves 110-113.ATM and dynamic reconfiguration allow for rapid changes in a virtual path network depending on traffic load and future demands. This technology improves the utilisation, lowers the call blocking probability and increases the overall performance of a network. However, it poses several management difficulties when user intervention is required to resolve complex routing problems. In this dissertation, we describe a visualisation approach which uses a network metaphor to aid administrators in managing dynamic ATM networks. Our metaphor scales well for networks of varying size, addresses the cluttering problem experienced by past metaphors and maintains the overall network context while providing additional support for navigation and interaction.
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Liu, Yunhuai. "Probabilistic topology control in wireless sensor networks /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?CSED%202008%20LIU.
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Rye, Erik C. "Evaluating the limits of network topology inference via virtualized network emulation." Thesis, Monterey, California: Naval Postgraduate School, 2015. http://hdl.handle.net/10945/45932.
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Approved for public release; distribution is unlimitedThe Internet measurement community is beset by a lack of ground truth, or knowledge of the real, underlying network in topology inference experiments. While better tools and methodologies can be developed, quantifying the effectiveness of these mapping utilities and explaining pathologies is difficult, if not impossible, without knowing the network topology being probed. In this thesis we present a tool that eliminates topological uncertainty in an emulated, virtualized environment. First, we automatically build topological ground truth according to various network generation models and create emulated Cisco router networks by leveraging and modifying existing emulation software. We then automate topological inference from one vantage point at a time for every vantage point in the network. Finally, we incorporate a mechanism to study common sources of network topology inference abnormalities by including the ability to induce link failures within the network. In addition, this thesis reexamines previous work in sampling Autonomous System-level Internet graphs to procure realistic models for emulation and simulation. We build upon this work by including additional data sets, and more recent Internet topologies to sample from, and observe divergent results from the authors of the original work. Lastly, we introduce a new technique for sampling Internet graphs that better retains particular graph metrics across multiple timeframes and data sets.
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Komali, Ramakant S. "Game-Theoretic Analysis of Topology Control." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/28358.
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Ad hoc networks are emerging as a cost-effective, yet, powerful tool for communication.
These systems, where networks can emerge and converge on-the-fly, are guided by the
forward-looking goals of providing ubiquitous connectivity and constant access to information.
Due to power and bandwidth constraints, the vulnerability of the wireless medium, and
the multi-hop nature of ad hoc networks, these networks are becoming increasingly complex
dynamic systems. Besides, modern radios are empowered to be reconfigurable, which harbors
the temptation to exploit the system. To understand the implications of these issues, some
of which pose significant challenges to efficient network design, we study topology control
using game theory.
We develop a game-theoretic framework of topology control that broadly captures the radio
parameters, one or more of which can be tuned under the purview of topology control. In
this dissertation, we consider two parameters, viz. transmit power and channel, and study
the impact of controlling these on the emergent topologies.
We first examine the impact of node selfishness on the network connectivity and energy
efficiency under two levels of selfishness: (a) nodes cooperate and forward packets for one
another, but selfishly minimize transmit power levels and; (b) nodes selectively forward
packets and selfishly control transmit powers. In the former case, we characterize all the
Nash Equilibria of the game and evaluate the energy efficiency of the induced topologies.
We develop a better-response-based dynamic that guarantees convergence to the minimal
maximum power topology. We extend our analysis to dynamic networks where nodes have
limited knowledge about network connectivity, and examine the tradeoff between network
performance and the cost of obtaining knowledge. Due to the high cost of maintaining
knowledge in networks that are dynamic, mobility actually helps in information-constrained
networks. In the latter case, nodes selfishly adapt their transmit powers to minimize their
energy consumption, taking into account partial packet forwarding in the network. This
work quantifies the energy efficiency gains obtained by cooperation and corroborates the
need for incentivizing nodes to forward packets in decentralized, energy-limited networks.
We then examine the impact of selfish behavior on spectral efficiency and interference minimization
in multi-channel systems. We develop a distributed channel assignment algorithm
to minimize the spectral footprint of a network while establishing an interference-free connected
network. In spite of selfish channel selections, the network spectrum utilization is
shown to be within 12% of the minimum on average. We then extend the analysis to dynamic
networks where nodes have incomplete network state knowledge, and quantify the price of
ignorance. Under the limitations on the number of available channels and radio interfaces, we
analyze the channel assignment game with respect to interference minimization and network
connectivity goals. By quantifying the interference in multi-channel networks, we illuminate
the interference reduction that can be achieved by utilizing orthogonal channels and by distributing
interference over multiple channels. In spite of the non-cooperative behavior of
nodes, we observe that the selfish channel selection algorithm achieves load balancing.
Distributing the network control to autonomous agents leaves open the possibility that nodes
can act selfishly and the overall system is compromised. We advance the need for considering
selfish behavior from the outset, during protocol design. To overcome the effects of
selfishness, we show that the performance of a non-cooperative network can be enhanced by
appropriately incentivizing selfish nodes.Ph. D.
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Mudali, Pragasen. "Topology control for wireless mesh networks and its effect on network performance." Thesis, University of Zululand, 2017. http://hdl.handle.net/10530/1565.
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A thesis submitted to the Faculty of Science and Agriculture in fulfilment of the Degree of Doctor of Philosophy in the Department of Computer Science at the University of Zululand, 2017InfrastructureWireless Mesh Networks (I-WMNs) are increasingly used to provide network connectivity and Internet access to previously under-served areas in the developing world. It is common for some of these deployments to be battery-powered due to a lack of electrical infrastructure in the targeted areas. Thus, the energy-efficiency of these networks gains additional importance. Topology Control (TC) has been previously reported to improve the energy-efficiency and network performance of wireless ad-hoc networks, including I-WMNs. However,simulation-based studies have been relied upon to reach these conclusions and the study of TC prototypes applicable to I-WMNs has largely been limited to design issues. Thus, the study of the efficacy of TC prototypes as a mechanism for improving energy-fficiency and network performance remains an open issue. The thesis addresses this knowledge gap by studying the dynamic, run-time behaviours and the network topologies created by two standards-compatible TC prototypes. This study provides unique insight into how the prototypes consume computational resources, maintain network connectivity, produce cumulative transceiver power savings and affect the workings of the routing protocol being employed. This study also documents the topology instability caused by transceiver power oscillations produced by the PlainTC prototype. A context-based solution to reduce transceiver power oscillations and the subsequent topology instability is proposed. This solution applies the Principal Component Analysis statistical method to historical network data in order to derive the weights associated with each of the identified context variables. A threshold value is defined that only permits a node to adjust its transceiver power output if the observed change in a node’s context exceeds the threshold. The threshold mechanism is incorporated into the PlainTC+ prototype and is shown to reduce topology instability whilst improving network performance when compared to PlainTC.The results obtained in this study suggest that I-WMN topologies formed by TC are able to closely match the performance of networks that do not employ TC. However, this study shows that TC negatively affects the energy efficiency of the network despite achieving cumulative transceiver power savings.
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Kasthurirathna, Dharshana Mahesh. "The influence of topology and information diffusion on networked game dynamics." Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/14570.
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This thesis studies the influence of topology and information diffusion on the strategic interactions of agents in a population. It shows that there exists a reciprocal relationship between the topology, information diffusion and the strategic interactions of a population of players. In order to evaluate the influence of topology and information flow on networked game dynamics, strategic games are simulated on populations of players where the players are distributed in a non-homogeneous spatial arrangement. The initial component of this research consists of a study of evolution of the coordination of strategic players, where the topology or the structure of the population is shown to be critical in defining the coordination among the players. Next, the effect of network topology on the evolutionary stability of strategies is studied in detail. Based on the results obtained, it is shown that network topology plays a key role in determining the evolutionary stability of a particular strategy in a population of players. Then, the effect of network topology on the optimum placement of strategies is studied. Using genetic optimisation, it is shown that the placement of strategies in a spatially distributed population of players is crucial in maximising the collective payoff of the population. Exploring further the effect of network topology and information diffusion on networked games, the non-optimal or bounded rationality of players is modelled using topological and directed information flow of the network. Based on the topologically distributed bounded rationality model, it is shown that the scale-free and small-world networks emerge in randomly connected populations of sub-optimal players. Thus, the topological and information theoretic interpretations of bounded rationality suggest the topology, information diffusion and the strategic interactions of socio-economical structures are cyclically interdependent.
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Spring, Neil Timothy. "Efficient discovery of network topology and routing policy in the Internet /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/6985.
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Terelius, Håkan, Guodong Shi, Jim Dowling, Amir Payberah, Ather Gattami, and Karl Henrik Johansson. "Converging an Overlay Network to a Gradient Topology." KTH, Reglerteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-46515.
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In this paper, we investigate the topology convergence problem for the gossip-based Gradient overlay network. In an overlay network where each node has a local utility value, a Gradient overlay network is characterized by the properties that each node has a set of neighbors containing higher utility values, such that paths of increasing utilities emerge in the network topology. The Gradient overlay network is built using gossiping and a preference function that samples from nodes using a uniform random peer sampling service. We analyze it using tools from matrix analysis, and we prove both the necessary and sufficient conditions for convergence to a complete gradient structure, as well as estimating the convergence time. Finally, we show in simulations the potential of the Gradient overlay, by building a more efficient live-streaming peer-to-peer (P2P) system than one built using uniform random peer sampling.© 2011 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. QC 20111124
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Li, Yuhong. "Disruption Information, Network Topology and Supply Chain Resilience." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/78352.
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This dissertation consists of three essays studying three closely related aspects of supply chain resilience.
The first essay is "Value of Supply Disruption Information and Information Accuracy", in which we examine the factors that influence the value of supply disruption information, investigate how information accuracy influences this value, and provide managerial suggestions to practitioners. The study is motivated by the fact that fully accurate disruption information may be difficult and costly to obtain and inaccurate disruption information can decrease the financial benefit of prior knowledge and even lead to negative performance. We perform the analysis by adopting a newsvendor model. The results show that information accuracy, specifically information bias and information variance, plays an important role in determining the value of disruption information. However, this influence varies at different levels of disruption severity and resilience capacity.
The second essay is "Quantifying Supply Chain Resilience: A Dynamic Approach", in which we provide a new type of quantitative framework for assessing network resilience. This framework includes three basic elements: robustness, recoverability and resilience, which can be assessed with respect to different performance measures. Then we present a comprehensive analysis on how network structure and other parameters influence these different elements. The results of this analysis clearly show that both researchers and practitioners should be aware of the possible tradeoffs among different aspects of supply chain resilience. The ability of the framework to support better decision making is then illustrated through a systemic analysis based on a real supply chain network.
The third essay is "Network Characteristics and Supply Chain Disruption Resilience", in which we investigate the relationships between network characteristics and supply chain resilience. In this work, we first prove that investigating network characteristics can lead to a better understanding of supply chain resilience behaviors. Later we select key characteristics that play a critical role in determining network resilience. We then construct the regression and decision tree models of different supply chain resilience measures, which can be used to estimate supply chain network resilience given the key influential characteristics. Finally, we conduct a case study to examine the estimation accuracy.Ph. D.
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Dhanapalan, Manojprasadh. "Topology-aware Correlated Network Anomaly Detection and Diagnosis." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1339742606.
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Elshqeirat, Basima Ahmad Haroun. "Optimizing reliable network topology design using dynamic programming." Thesis, Curtin University, 2015. http://hdl.handle.net/20.500.11937/823.
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This thesis addresses four reliable network topology design problems that consider reliability, cost, and/or bandwidth performance metrics. The optimization problems include one or two objectives and one constraint, each of which is known NP-hard. All problems consider all-terminal and/or two-terminal reliability measures. Four heuristic dynamic programming approaches are proposed, and 10 order criteria are used to improve their optimality and time efficiency. Simulations on hundreds of networks show the merits of the proposed methods.
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Perera, Pannilage Supun Sachinthaka. "Topological Approach for Modelling the Structure, Dynamics and Robustness of Supply Chain Networks." Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/20418.
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Traditionally simple and linear supply chains have, in recent years, evolved towards highly complex networked systems, due to globalisation and product specialisation. Recent application of network models to supply chain systems have revealed the existence of non-trivial and universal topological footprints, which provide important system level insights. This thesis uses topological network models to investigate the structure, dynamics and robustness of supply chain networks (SCNs). Firstly, the common topological characteristics of real-world SCNs are identified, by considering both undirected inter-firm relationship and directed material flow SCNs. Based on this analysis, it is evident that the number of firm-level connections in each SCN follow the power law distribution with power law exponents in the range of 1.5 - 3.5. A fitness-based growth model is then presented to simulate such topologies. The mechanism through which this growth model operates is justified on the basis of risk averse firm behaviour. The second half of this thesis is concerned with the role of SCN topology on the evolution of cooperation and robustness. It is found that the SCN topology, the level of rationality of firms and the relative payoff differences are all essential elements in the evolution of co-operation when strategic inter-firm interactions in an SCN are represented as Prisoner Dilemma games. Finally, a novel methodology to quantify and improve the robustness of material flow SCNs is presented. Here, the specific case of a material flow SCN with multi-sourcing, which is characterised by a tiered structure with directed and weighted links, is considered. An indicative robustness metric is proposed to characterise the robustness of the SCN, considering the degree to which supply chains overlap with each other. Since this model incorporates information beyond the topology of the SCN, it is a useful tool for decision making by the practitioners.
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Kamei, Hiroko. "Interplay between network topology and synchrony-breaking bifurcation : homogeneous four-cell coupled networks." Thesis, University of Warwick, 2008. http://wrap.warwick.ac.uk/2126/.
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Complex networks are studied across many fields of science. Much progress has been made on static and statistical features of networks, such as small world and scale-free networks. However, general studies of network dynamics are comparatively rare. Synchrony is one commonly observed dynamical behaviour in complex networks. Synchrony breaking is where a fully synchronised network loses coherence, and breaks up into multiple clusters of self-synchronised sub-networks. Mathematically this can be described as a bifurcation from a fully synchronous state, and in this thesis we investigate the effect of network topology on synchrony-breaking bifurcations. Coupled cell networks represent a collection of individual dynamical systems (termed cells) that interact with each other. Each cell is described by an ordinary differential equation (ODE) or a system of ODEs. Schematically, the architecture of a coupled cell network can be represented by a directed graph with a node for each cell, and edges indicating cell couplings. Regular homogeneous networks are a special case where all the nodes/cells and edges are of the same type, and every node has the same number of input edges, which we call the valency of the network. Classes of homogeneous regular networks can be counted using an existing group theoretic enumeration formula, and this formula is extended here to enumerate networks with more generalised structures. However, this does not generate the networks themselves. We therefore develop a computer algorithm to display all connected regular homogeneous networks with less than six cells and analysed synchrony-breaking bifurcations for four-cell regular homogeneous networks. Robust patterns of synchrony (invariant synchronised subspaces under all admissible vector fields) describe how cells are divided into multiple synchronised clusters, and their existence is solely determined by the network topology. These robust patterns of synchrony have a hierarchical relationship, and can be treated as a partially ordered set, and expressed as a lattice. For each robust pattern of synchrony (or lattice point) we can reduce the original network to a smaller network, called a quotient network, by representing each cluster as a single combined node. Therefore, the lattice for a given regular homogeneous network provides robust patterns of synchrony and corresponding quotient networks. Some lattice structures allow a synchrony breaking bifurcation analysis based solely on the dynamics of the quotient networks, which are lifted to the original network using the robust patterns of synchrony. However, in other cases the lattice structure also tells us of the existence and location of additional synchrony-breaking bifurcating branches not seen in the quotient networks. In conclusion the work undertaken here shows that the invariant synchronised subspaces that arise from a network topology facilitate the classification of synchrony-breaking bifurcations of networks.
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Tran, Thi-Minh-Dung. "Methods for finite-time average consensus protocols design, network robustness assessment and network topology reconstruction." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAT023/document.
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Le consensus des systèmes multi-agents a eu une attention considérable au cours de la dernière décennie. Le consensus est un processus coopératif dans lequel les agents interagissent afin de parvenir à un accord. La plupart des études se sont engagés à l'analyse de l'état d'équilibre du comportement de ce processus. Toutefois, au cours de la transitoire de ce processus une énorme quantité de données est produite. Dans cette thèse, notre objectif est d'exploiter les données produites au cours de la transitoire d'algorithmes de consensus moyenne asymptotique afin de concevoir des protocoles de consensus moyenne en temps fini, évaluer la robustesse du graphique, et éventuellement récupérer la topologie du graphe de manière distribuée. Le consensus de moyenne en temps fini garantit un temps d'exécution minimal qui peut assurer l'efficacité et la précision des algorithmes distribués complexes dans lesquels il est impliqué. Nous nous concentrons d'abord sur l'étape de configuration consacrée à la conception de protocoles de consensus qui garantissent la convergence de la moyenne exacte dans un nombre donné d'étapes. En considérant des réseaux d'agents modélisés avec des graphes non orientés connectés, nous formulons le problème de la factorisation de la matrice de moyenne et étudions des solutions distribuées à ce problème. Puisque, les appareils communicants doivent apprendre leur environnement avant d'établir des liens de communication, nous suggérons l'utilisation de séquences d'apprentissage afin de résoudre le problème de la factorisation. Ensuite, un algorithme semblable à l'algorithme de rétro-propagation du gradient est proposé pour résoudre un problème d'optimisation non convexe sous contrainte. Nous montrons que tout minimum local de la fonction de coût donne une factorisation exacte de la matrice de moyenne. En contraignant les matrices de facteur à être comme les matrices de consensus basées sur la matrice laplacienne, il est maintenant bien connu que la factorisation de la matrice de moyenne est entièrement caractérisé par les valeurs propres non nulles du laplacien. Par conséquent, la résolution de la factorisation de la matrice de la moyenne de manière distribuée avec une telle contrainte sur la matrice laplacienne, permet d'estimer le spectre de la matrice laplacienne. Depuis le spectre peut être utilisé pour calculer des indices de la robustesse (Nombre d'arbres couvrant et la résistance effective du graphe), la deuxième partie de cette thèse est consacrée à l'évaluation de la robustesse du réseau à travers l'estimation distribuée du spectre du Laplacien. Le problème est posé comme un problème de consensus sous contrainte formulé de deux façons différentes. La première formulation (approche directe) cède à un problème d'optimisation non-convexe résolu de manière distribuée au moyen de la méthode des multiplicateurs de Lagrange. La seconde formulation (approche indirecte) est obtenue après une reparamétrisation adéquate. Le problème est alors convexe et résolu en utilisant l'algorithme du sous-gradient distribué et la méthode de direction alternée de multiplicateurs. En outre, trois cas sont considérés: la valeur moyenne finale est parfaitement connue, bruyant, ou complètement inconnue. Nous fournissons également une façon pour calculer les multiplicités des valeurs propres estimées au moyen d'une programmation linéaire en nombres entiers. L'efficacité des solutions proposées est évaluée au moyen de simulations. Cependant, dans plusieurs cas, la convergence des algorithmes proposés est lente et doit être améliorée dans les travaux futurs. En outre, l'approche indirecte n'est pas évolutive pour des graphes de taille importante car elle implique le calcul des racines d'un polynôme de degré égal à la taille du réseau. Cependant, au lieu d'estimer tout le spectre, il peut être possible de récupérer seulement un petit nombre des valeurs propres, puis déduire des limites significatives sur les indices de la robustesseConsensus of Multi-agent systems has received tremendous attention during the last decade. Consensus is a cooperative process in which agents interact in order to reach an agreement. Most of studies are committed to analysis of the steady-state behavior of this process. However, during the transient of this process a huge amount of data is produced. In this thesis, our aim is to exploit data produced during the transient of asymptotic average consensus algorithms in order to design finite-time average consensus protocols, assess the robustness of the graph, and eventually recover the topology of the graph in a distributed way. Finite-time Average Consensus guarantees a minimal execution time that can ensure the efficiency and the accuracy of sophisticated distributed algorithms in which it is involved. We first focus on the configuration step devoted to the design of consensus protocols that guarantee convergence to the exact average in a given number of steps. By considering networks of agents modelled with connected undirected graphs, we formulate the problem as the factorization of the averaging matrix and investigate distributed solutions to this problem. Since, communicating devices have to learn their environment before establishing communication links, we suggest the usage of learning sequences in order to solve the factorization problem. Then a gradient backpropagation-like algorithm is proposed to solve a non-convex constrained optimization problem. We show that any local minimum of the cost function provides an accurate factorization of the averaging matrix. By constraining the factor matrices to be as Laplacian-based consensus matrices, it is now well known that the factorization of the averaging matrix is fully characterized by the nonzero Laplacian eigenvalues. Therefore, solving the factorization of the averaging matrix in a distributed way with such Laplacian matrix constraint allows estimating the spectrum of the Laplacian matrix. Since that spectrum can be used to compute some robustness indices (Number of spanning trees and Effective graph Resistance also known as Kirchoff index), the second part of this dissertation is dedicated to Network Robustness Assessment through distributed estimation of the Laplacian spectrum. The problem is posed as a constrained consensus problem formulated in two ways. The first formulation (direct approach) yields a non-convex optimization problem solved in a distributed way by means of the method of Lagrange multipliers. The second formulation (indirect approach) is obtained after an adequate re-parameterization. The problem is then convex and solved by using the distributed subgradient algorithm and the alternating direction method of multipliers. Furthermore, three cases are considered: the final average value is perfectly known, noisy, or completely unknown. We also provide a way for computing the multiplicities of the estimated eigenvalues by means of an Integer programming. In this spectral approach, given the Laplacian spectrum, the network topology can be reconstructed through estimation of Laplacian eigenvector. The efficiency of the proposed solutions is evaluated by means of simulations. However, in several cases, convergence of the proposed algorithms is slow and needs to be improved in future works. In addition, the indirect approach is not scalable to very large graphs since it involves the computation of roots of a polynomial with degree equal to the size of the network. However, instead of estimating all the spectrum, it can be possible to recover only a few number of eigenvalues and then deduce some significant bounds on robustness indices
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Srivastava, Gaurav. "Efficient topology control algorithms for ad hoc networks." Access electronically, 2006. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20080506.144718/index.html.
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Hammarström, Emil. "Network optimisation and topology control of Free Space Optics." Thesis, Linköpings universitet, Kommunikations- och transportsystem, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-124546.
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In communication networks today, the amount of users and traffic is constantly increasing. This results in the need for upgrading the networks to handle the demand. Free space optics is a technique which is relatively cheap with high capacity compared to most systems today. On the other hand, FSO have some disadvantages with the effects on the system by, for instance, turbulence and weather. The aim of the project is to investigate the use of network optimization for designing an optimal network in terms of capacity and cost. Routing optimization is also covered in terms of singlepath and multipath routing. To mitigate the problem with turbulence affecting the system network survivability is implemented with both proactive and reactive solutions. The method used is to implement the system in Matlab, the system should also be tested so that it works as intended. The report covers related work as well as theory behind FSO and the chosen optimization algorithms. The system uses modified Bellman-Ford optimization as well as Kruskal’s minimum spanning tree. K-link-connectivity is also implemented for the network survivability and multipath algorithm. Results of the implementation shows that the network survivability improves the robustness of the system by changing paths for traffic which is affected by broken links. Routing done by multipath will increase the throughput and also reduce the delay for the traffic.
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Nordkvist, Tobias. "Network optimisation and topology control of Free Space Optics." Thesis, Linköpings universitet, Kommunikations- och transportsystem, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-130003.
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In communication networks today, the amount of users and traffic is constantly increasing. This results in the need for upgrading the networks to handle the demand. Free space optics, FSO, is a technique which is relatively cheap with high capacity compared to most systems today. On the other hand, FSO have some disadvantages with the effects on the system by, for instance, turbulence and weather. The aim of the project is to investigate the use of network optimization for designing an optimal network in terms of capacity and cost. Routing optimization is also covered in terms of singlepath and multipath routing. To mitigate the problem with turbulence affecting the system network survivability is implemented with both proactive and reactive solutions. The method used is to implement the system in Matlab, the system should also be tested so that it works as intended. The report covers related work as well as theory behind FSO and the chosen optimization algorithms. The system uses modified Bellman-Ford optimization as well as Kruskals minimum spanning tree. K-link-connectivity is also implemented for the network survivability and multipath algorithm. Results of the implementation shows that the network survivability improves the robustness of the system by changing paths for traffic which is affected by broken links. Routing done by multipath will increase the throughput and also reduce the delay for the traffic.
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Scheidemantel, Austin, Ibrahim Alnasser, Benjamin Carpenter, Paul Frost, Shivhan Nettles, and Chelsie Morales. "Situational Wireless Awareness Network." International Foundation for Telemetering, 2010. http://hdl.handle.net/10150/604295.
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ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, CaliforniaThe purpose of this paper is to explain the process to implementing a wireless sensor network in order to improve situational awareness in a dense urban environment. Utilizing a system of wireless nodes with Global Positioning System (GPS) and heart rate sensors, a system was created that was able to give both position and general health conditions. By linking the nodes in a mesh network line of sight barriers were overcome to allow for operation even in an environment full of obstruction.
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Weighill, Deborah A. "Exploring the topology of complex phylogenomic and transcriptomic networks." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/95800.
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Thesis (MSc)--Stellenbosch University, 2014.ENGLISH ABSTRACT: This thesis involved the development and application of network approaches for the construction, analysis and visualization of phylogenomic and transcriptomic networks. A co-evolutionary network model of grapevine genes was constructed based on three mechanisms of evolution. The investigation of local neighbourhoods of this network revealed groups of functionally related genes, illustrating that the multi-mechanism evolutionary model was identifying groups of potentially co-evolving genes. An extended network definition, namely 3-way networks, was investigated, in which edges model relationships between triplets of objects. Strategies for weighting and pruning these 3-way networks were developed and applied to a phylogenomic dataset of 211 bacterial genomes. These 3-way bacterial networks were compared to standard 2-way network models constructed from the same dataset. The 3-way networks modelled more complex relationships and revealed relationships which were missed by the two-way network models. Network meta-modelling was explored in which global network and node-bynode network comparison techniques were applied in order to investigate the effect of the similarity metric chosen on the topology of multiple types of networks, including transcriptomic and phylogenomic networks. Two new network comparison techniques were developed, namely PCA of Topology Profiles and Cross-Network Topological Overlap. PCA of Topology Profiles compares networks based on a selection of network topology indices, whereas Cross- Network Topological Overlap compares two networks on a node-by-node level, identifying nodes in two networks with similar neighbourhood topology and thus highlighting areas of the networks with conflicting topologies. These network comparison methods clearly indicated how the similarity metric chosen to weight the edges of the network influences the resulting network topology, consequently influencing the biological interpretation of the networks.
AFRIKAANSE OPSOMMING: Hierdie tesis hou verband met die ontwikkeling en toepassing van netwerk benaderings vir die konstruksie, analise en visualisering van filogenomiese en transkriptomiese netwerke. 'n Mede-evolusionêre netwerk model van wingerdstok gene is gebou, gebaseerd op drie meganismes van evolusie. Die ondersoek van plaaslike omgewings van die netwerk het groepe funksioneel verwante gene aan die lig gebring, wat daarop dui dat die multi-meganisme evolusionêre model groepe van potensieele mede-evolusieerende gene identifiseer. 'n Uitgebreide netwerk definisie, naamliks 3-gang netwerke, is ondersoek, waarin lyne die verhoudings tussen drieling voorwerpe voorstel. Strategieë vir weeg en snoei van hierdie 3-gang netwerke was ontwikkel en op 'n filogenomiese datastel van 211 bakteriële genome toegepas. Hierdie 3-gang bakteriële netwerke is met die standaard 2-gang netwerk modelle wat saamgestel is uit dieselfde datastel vergelyk. Die 3-gang netwerke het meer komplekse verhoudings gemodelleer en het verhoudings openbaar wat deur die tweerigting-netwerk modelle gemis is. Verder is netwerk meta-modellering ondersoek waarby globalle netwerk en punt-vir-punt netwerk vergelykings tegnieke toegepas is, met die doel om die effek van die ooreenkoms-maatstaf wat gekies is op die topologie van verskeie tipes netwerke, insluitend transcriptomic en filogenomiese netwerke, te bepaal. Twee nuwe netwerk-vergelyking tegnieke is ontwikkel, naamlik "PCA of Topology Profiles" en"Cross-Network Topological Overlap". PCA van Topologie Profiele vergelyk netwerke gebaseer op 'n seleksie van netwerk topologie indekse, terwyl Cross-netwerk Topologiese Oorvleuel vergelyk twee netwerke op 'n punt-vir-punt vlak, en identifiseer punte in twee netwerke met soortgelyke lokale topologie en dus lê klem op gebiede van die netwerke met botsende topologieë. Hierdie netwerk-vergelyking metodes dui duidelik aan hoe die ooreenkoms maatstaf wat gekies is om die lyne van die netwerk gewig te gee, die gevolglike netwerk topologie beïnvloed, wat weer die biologiese interpretasie van die netwerke kan beïnvloed.
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Obenaus, Stefan Thomas Henning. "Topology of a high speed free-space photonic network." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22867.
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In this thesis, we investigate the suitability of several routing schemes and network topologies for a high speed free-space photonic network that is currently being developed at McGill.We find that deflection routing is a very suitable routing strategy since it does not require expensive buffers at network nodes, and it does not experience deadlock.
After reviewing current research in deflection routing for a variety of network topologies, we conclude that the 11 $ times$ 11-torus, the 5-symbol star graph, and the 7-dimensional hypercube are attractive candidates for a photonic network of approximately 120 nodes.
Then, we determine efficient embeddings of these three networks into an optical hyperplane which hosts the communication channels of the network in one and two dimensions. While trying to embed the 5-star into the two-dimensional hyperplane, we discover an embedding strategy which allows any n-star to be embedded into any d-dimensional grid of size at most ${ underbrace{n times ... times n} sb{d-1}} times (n!/d!)$ without any bends between neighbours in the n-star.
Through simulation, we determine that for a network size of about 120 nodes, the hypercube in seven dimensions offers the most dependable behaviour since its throughput is always above 99.6% and the delay is never greater than 20% of the average distance. However, when we allocate an equal number of communication channels to each node, we find that the star graph offers superior performance due to its low degree and diameter, and when we assign an equal number of communication channels to the three topologies as a whole, the torus outperforms the star and cube due to its efficient embeddings in the hyperplane.
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Trassare, Samuel T. "A Technique for Presenting a Deceptive Dynamic Network Topology." Monterey, California: Naval Postgraduate School, 2013. http://hdl.handle.net/10945/32911.
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Approved for public release; distribution is unlimitedAdversaries scan Department of Defense networks looking for vulnerabilities that allow surveillance or the embedding of destructive malware weapons. In cyberspace, adversaries either actively probe or passively observe defended computer networks in attempts to determine, among other attributes, the topology of the network. We develop a novel strategic deceptive methodology, based on principles of military deception, for deceiving a malicious traceroute probe in defense of a physical data communications network. We construct a proof-of-concept network to show that a remote adversary who uses traceroute to map the defended network_s topology can be presented with a false route of the defender_s choosing. Akin to military deception operations in the field and at sea, a network that employs a deception scheme implemented on an intelligent border router can present a deceptive topology to an adversary. Our experiments show that a defender using our technique can successfully deceive a traceroute probe, the first in a sequence of steps to mount a credible deception scheme against an adversary.
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Hughes, Jason J. "Employing deceptive dynamic network topology through software-defined networking." Thesis, Monterey, California: Naval Postgraduate School, 2014. http://hdl.handle.net/10945/41392.
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Approved for public release; distribution is unlimited.Computer networks are constantly being actively probed in attempts to build topological maps of intermediate nodes and discover endpoints, either for academic research or nefarious schemes. While some networks employ recommended conventional countermea-sures to simply block such probing at the boundary or shunt such traffic to honey pot systems, other networks remain completely open either by design or neglect. Our research builds on previous work on the concept of presenting a deceptive network topology, which goes beyond conventional network security countermeasures of detecting and blocking network probe traffic. By employing the technologies from the emerging field of Software-Defined Networking and the OpenFlow protocol, we constructed a custom-built SDN controller to listen for network probes and craft customized deceptive replies to those probes. Through employment of various network probing utilities against our custom-built SDN controller in a test network environment, we are able to present a believable deceptive representation of the network topology to an adversary. Therefore, this work demonstrates that the primitives of the expand-ing OpenFlow protocol show strong potential for constructing an enterprise-grade dynamic deceptive network topology solution to protect computer networks.
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Baltra, Guillermo P. "Efficient strategies for active interface-level network topology discovery." Thesis, Monterey, California: Naval Postgraduate School, 2013. http://hdl.handle.net/10945/37583.
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Approved for public release; distribution is unlimitedAs a piece of critical infrastructure, the Internet brings both benefits and security concerns. Recent cyber-security episodes such as route hijacks and Denial-of-Service attacks might have been mitigated and prevented with better knowledge of the network_s logical topology; i.e., router nodes and links. Current production public active mapping systems; e.g., Ark, Rocketfuel, and iPlane, produce valuable inferences of the Internet_s topology, as well as facilitating longitudinal analysis. We examine the extent to which the techniques utilized by these existing systems can be improved, in particular by attempting to reduce their high probing load. Our methodology divides the discovery process into three steps: destination selection, monitor assignment, and stop criterion. We implement and evaluate alternative designs for each step. The complete system runs in real-time on a production system to probe 500 randomly selected Internet subnetworks and gather real-world network maps. As compared to datasets from existing measurement platforms, we find that our method is able to generate 80% of the amount of data with 69% less load.
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Ali, Baraa Saeed. "HIGH LEVEL SYNTHSIS FOR A NETWORK ON CHIP TOPOLOGY." OpenSIUC, 2013. https://opensiuc.lib.siu.edu/theses/1079.
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Network on chips (NoCs) have emerged as a panacea to solve many intercommunication issues that are imposed by the fast growing of VLSI design. NOC have been deployed as a solution for the communication delay between cores, area overhead, power consumption, etc. One of the leading parameters of speeding up the performance of system on chips (SOCs) is the efficiency of scheduling algorithms for the applications running on a SOC. In this thesis we are arguing that a global scheduling view can significantly improve latency in NoCs. This view can be achieved by having the NoC nodes communicate with each other in a predefined application-based fashion; by calculating in advance how many clock cycles the nodes need to execute and transmit packets to the network and how many clock cycles are needed for the packets to travel all the way to the destination through routers (including queuing delay). By knowing that, we could keep some of the cores stay in "Hold-On" state until the right time comes to start transmitting. This technique could lead to reduced congestion and it may guarantee that the cores do not suffer from severe resource contention, e.g. accessing memory. This task is achieved by using a network simulator (such as OPNET) and gathering statistics, so the worst case latency can be determined. Therefore, if NoC nodes can somehow postpone sending packets in a way that does not violate the deadline of their tasks, packet dropping or livelock can be avoided. It is assumed that the NoC nodes here need buffers of their own in order to hold the ready-to-transmit packets and this can be the cost of this approach.
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Zhou, Yuanyuan. "Energy-efficient protocols and topologies for sensor and personal-area networks." Online access for everyone, 2007. http://www.dissertations.wsu.edu/Dissertations/Summer2007/y_zhou_072307.pdf.
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Pennington, Nicholas. "Network Properties of Optically Linked Planetary Satellite Systems." OpenSIUC, 2020. https://opensiuc.lib.siu.edu/theses/2702.
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With plans for advancing into the rest of the solar system in the coming decades, an understanding of how interlinked satellite systems behave as a network will be essential. The relatively recent development of optics as a method of space communication means that inter-satellite networks are more feasible than ever. That said, there are currently no analyses which take into account a planet-wide, largely uncoordinated, optically linked satellite network. To provide a look at the properties of such a network, movement and connections of Earth's currently active satellites were simulated based on real-world data, and their networks modeled via graphs. Ultimately, it was found that many properties of such a network are periodic, fluctuating in sync with the orbital time of low-earth orbit satellites. This, among other data, suggests that the peaks of these waves are caused by a meeting of satellites near the north and south poles.
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Wightman, Rojas Pedro Mario. "Topology Control in Wireless Sensor Networks." Scholar Commons, 2010. https://scholarcommons.usf.edu/etd/1807.
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Wireless Sensor Networks (WSN) offer a flexible low-cost solution to the problem of event monitoring, especially in places with limited accessibility or that represent danger to humans. WSNs are made of resource-constrained wireless devices, which require energy efficient mechanisms, algorithms and protocols. One of these mechanisms is Topology Control (TC) composed of two mechanisms, Topology Construction and Topology Maintenance.
This dissertation expands the knowledge of TC in many ways. First, it introduces a comprehensive taxonomy for topology construction and maintenance algorithms for the first time. Second, it includes four new topology construction protocols: A3, A3Lite, A3Cov and A3LiteCov. These protocols reduce the number of active nodes by building a Connected Dominating Set (CDS) and then turning off unnecessary nodes. The A3 and A3-Lite protocols guarantee a connected reduced structure in a very energy efficient manner. The A3Cov and A3LiteCov protocols are extensions of their predecessors that increase the sensing coverage of the network. All these protocols are distributed -they do not require localization information, and present low message and computational complexity. Third, this dissertation also includes and evaluates the performance of four topology maintenance protocols: Recreation (DGTRec), Rotation (SGTRot), Rotation and Recreation (HGTRotRec), and Dynamic Local-DSR (DLDSR).
Finally, an event-driven simulation tool named Atarraya was developed for teaching, researching and evaluating topology control protocols, which fills a need in the area of topology control that other simulators cannot. Atarraya was used to implement all the topology construction and maintenance cited, and to evaluate their performance. The results show that A3Lite produces a similar number of active nodes when compared to A3, while spending less energy due to its lower message complexity. A3Cov and A3CovLite show better or similar coverage than the other distributed protocols discussed here, while preserving the connectivity and energy efficiency from A3 and A3Lite. In terms of network lifetime, depending on the scenarios, it is shown that there can be a substantial increase in the network lifetime of 450% when a topology construction method is applied, and of 3200% when both topology construction and maintenance are applied, compared to the case where no topology control is used.
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Davis, Joseph A. Sr. "An analysis of network and sensor performance within IEEE 802.x wireless MESH networks in the Tactical Network Topology (TNT)." Thesis, Monterey California. Naval Postgraduate School, 2005. http://hdl.handle.net/10945/2297.
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Approved for public release, distribution is unlimitedThe objective of this research is to analyze the network performance and sensor functionality, efficacy and usability of IEEE 802.x wireless MESH networks within a DoD Tactical network environment. Multiple sensor configurations operating with wireless MESH network technologies will be researched and analyzed for performance in expeditionary environment situations. Specifically, this thesis will attempt establish the foundation for the development of wireless MESH "network health" models by examining the performance of sensors operating within a MESH network and define which network performance metrics equate to good quality of service. This research will experiment with different application, sensor, and network configurations of currently available COTS components, such as, voice, video and data hardware. This thesis will lay the groundwork for wireless network MESH predictability, which will enable the optimal use of sensors within a tactical network environment.
Lieutenant Commander, United States Navy
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Davis, Joseph A. "An analysis of network and sensor performance within IEEE 802.x wireless MESH networks in the Tactical Network Topology (TNT) /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Mar%5FDavis.pdf.
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Thesis (M.S. in Information Technology Management)--Naval Postgraduate School, March 2005.Thesis Advisor(s): Alexander Bordetsky. Includes bibliographical references (p. 49-50). Also available online.
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Pucci, Lorenzo, and Lorenzo Pucci. "Development of a Simulation Platform for Wireless Network Topology Inference." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
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The importance of networks, in their broad sense, is rapidly and massively growing in modern day society thanks to unprecedented communication capabilities offered by technology. A sensor network deployed to collect environmental data (i.e., humidity, temperature) or a tactical network aiming to exchange information between soldiers, are only few examples of the vastness of networks widely diffused today. In this scenario of ultra-densely connected objects, the knowledge of network topology is an essential aspect that can help to predict traffic flow, infer the potential receivers of a currently active transmitter, understand the degree of connectivity of users, help network maintenance and optimization. For this reason, the development of an ad-hoc simulator for wireless network topologies is necessary, if not mandatory, for the generation and the collection of big amounts of data as much as possible realistic and precise. In this work, a wireless network simulator based on ns-3 open source infrastructure is developed and tested. Furthermore, the high-quality data generated with the simulator are used to evaluate the accuracy of a machine learning based topology inference algorithm.
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Kakkar, Aditya. "Theoretical Investigation of a new OFDM Access-Network Topology (OTONES)." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-128712.
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Recent studies on growth of telecomm sector depict an ever rising demand for high bandwidth applications such as on-line gaming, high definition television and many more. This demand is coupled with increase in internet connected utilities per house hold - each requiring a portion of bandwidth. The fast development of broadband telecommunication services calls for an upgrade of access infrastructure. This challenge could be met by technologies such as Fiber-To-The-Home/Building (FTTH/B) point-to-multipoint (P2MP) optical access networking. Further, FTTH is also widely regarded as a future proof solution for broadband telecommunication services within scientific and industrial sectors. This has encouraged large amount of research and development throughout the globe to find optimal topologies for FTTH. OFDM based optical access network topology abbreviated as OTONES is an ongoing EU FP 7 project under the PIANO+ framework. The OTONES project addresses the next generation optical access networking on the basis of Orthogonal Frequency Division Multiplexing (OFDM) and Orthogonal Frequency Multiple Access (OFDMA), with special provision for reduced complexity and signal processing aspects of the subscriber side terminals (ONUs). This thesis focuses on the theoretical investigation of OFDM based optical access network topology OTONES. The thesis provides an in depth view of the salient aspects of the topology and formulates the key requirements of OTONES topology. The investigation primarily delves on two important aspects of the topology. First, finding the optimal analog circuitry for the optical network unit (ONU). Second, finding the optimal operation regime for the topology and hence optimizing the system level concept. In this thesis, we show that the requirement of an analog circuitry originates from the need of successive up-conversions in OTONES topology which also produces image spectrum. This image spectrum causes a 3 dB loss in power and spectral efficiency in absence of a proper image rejection circuitry. Thus, we discuss the generic SSB generation methods for efficient image rejection. Novel Bedrosian method based on Bedrosian Theorem is established as a promising method for image rejection. We show that this method is an analog implementation of Hilbert Transform Method and does not involve any approximation. Both generic methods for SSB along with the Novel Bedrosian method are evaluated based on the criterion established for OTONES topology. Finally, optical filtering from the set of generic SSB method is proposed for the downstream path and Novel Bedrosian method is proposed for the upstream path. The tolerance limits for Novel Bedrosian method, are also established for its physical implementation. We further discuss the realistic implementation of various components of the OTONES topology. We also establish the optimal operation regime of the full concurrent topology based on parameters such as input optical power, pilot tone separation and many more. Finally as a key feature of the thesis, we optimize the system level concept of the topology with the use of the proposed Novel Bedrosian Method as the optimal analog circuitry for OTONES topology and provide a region of optimal operation of the topology.
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Tseng, Li-Ching, and 曾麗青. "Network Topology Display Problem." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/48736757097714084161.
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碩士國立交通大學
資訊管理研究所
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Since networks continue to grow at a rapid pace and with greater complexity, to have an efficient network management system becomes more important than ever. The network topology display service is one of the essential services that Configuration Management provides. For most existing network management systems, this service is supported by either an X-window based drawing tool or an automatic detection and drawing procedure. When the network grows larger and becomes more complicate, user must spend a great deal of time in adjusting network devices’ ICON, so as to get a good graphic layout. How to acquire a symmetric network topology display is called the Network Topology Display Problem (NTDP). Usually, NTDP is solved by a two-step procedure. In the first step, Intra-subnetwork algorithms are developed according to the types of the subnetwork. such as Ring、Bus etc.. In the second step, the inter-subnetworks algorithm is used to adjust the relative position between subnetworks. A Heuristic method had been proposed to handle the inter-subnetworks display problem. However, this method has difficulties in solving large size problems. The purpose of this paper is to find an efficient and effectiveness inter-subnetworks algorithm. Three methods, Modified Heuristic Method、Operations Research Method, and Neural Network Methods, are proposed Computational results obtained from these four methods are analyzed with respect to their effectiveness, running speed, and complexity. From the analysis, the following conclusions can be drawn. The Modified Heuristic Method performs best when the number of subnetworks is less than 50. However, once the number of subnetworks is over 50, the Operations Research Method has the best result in both running time and effectiveness.
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Li, Xiaozhou. "Ranch: a dynamic network topology." Thesis, 2004. http://hdl.handle.net/2152/1238.
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Li, Xiaozhou Plaxton C. Greg. "Ranch a dynamic network topology /." 2004. http://wwwlib.umi.com/cr/utexas/fullcit?p3143301.
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苗育本. "Topology of Hierarchiccal-Ring Network." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/61050460376012937312.
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Ansari, Almas Yuan Xin. "Topology aggregation for networks with two additive metrics." 2004. http://etd.lib.fsu.edu/theses/available/etd-07122004-144319.
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Thesis (M.S.)--Florida State University, 2004.Advisor: Dr. Xin Yuan, Florida State University, College ofArts and Sciences, Dept. of Computer Science. Title and description from dissertation home page (viewed Sept. 24, 2004). Includes bibliographical references.
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Costa, Fábio Rafael Azevedo. "Internet tomography : network topology discovery and network performance evaluation." Master's thesis, 2013. http://hdl.handle.net/1822/27830.
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Disertação de mestrado em Redes e Serviços de ComunicaçãoDue to the security threats and complexity of network services, such as video conferencing, internet telephony or online gaming, which require high QoS guarantees, the need for monitoring and evaluating network performance, in order to promptly detect and face security threats and malfunctions, is crucial to the correct operation of networks and network-based services. As the internet evolves in size and diversity, these tasks become difficult and demanding. Moreover, administrative limitations can restrict the position and the scope of the links to be monitored, while legislation imposes limitations on the information that can be collected and exported for monitoring purposes and almost all organization can't monitor or have knowledge or evaluate the performance of the entire network. They only can do this to part of the network, which corresponds to their own network. In this thesis, we propose the use of tomographic techniques for network topology discovery and performance evaluation. Network tomography studies the internal characteristics of the network using end-to-end probes, ie, it does not need the cooperation of the internal nodes of the network and can be successfully adopted in almost all scenarios. Thus, it is possible to have knowledge of the network characteristics out of the administrative borders. In this thesis we propose a new approach to Probe Packet Sandwich, where we use TTL-limited probes to infer the delay of a path hop-by-hop. We have shown that this approach is more effective than existing ones. This work was developed under the ERASMUS student mobility program, in the Telecommunication Networks Research Group, Dept. of Information Engineering, University of Pisa.
Devido às ameaças de segurança e complexidade dos serviços de rede, tais como videoconferência, telefonia via Internet ou jogos on-line, que exigem altas garantias de QoS, a necessidade de monotorização e avaliação de desempenho da rede, a fim de detectar prontamente e enfrentar as ameaças de segurança e mau funcionamento, é crucial para o correto funcionamento das redes e serviços baseados em rede. À medida que a Internet evolui em tamanho e diversidade, essas tarefas tornam-se difíceis e exigentes. Além disso, as limitações administrativas podem restringir a posição e o alcance dos links a serem monitorizados, enquanto a legislação impõe limitações sobre as informações que podem ser coletadas e exportadas para fins de monotorização e quase todas as organizações não podem controlar ou ter conhecimento ou avaliar o desempenho de toda a rede. Eles só podem fazer isso a parte da rede, o que corresponde à sua própria rede. Neste trabalho, nós propomos o uso de técnicas tomográficas para a descoberta da topologia da rede e avaliação de desempenho. A tomografia de rede estuda as características internas da rede usando medições fim-a-fim, ou seja, não necessita da ajuda dos nós internos da rede, podendo ser adoptadas com sucesso em quase todos os cenários. Desta maneira é possível obter conhecimento das características da rede para além dos limites administrativos. Neste tranalho propomos uma nova abordagem do Packet Sandwich Probe, onde utilizamos pacotes TTL-Limited para inferir o delay de um path hop-by-hop. Nós mostramos que esta abordagem é mais eficaz que outras já existentes. Este trabalho foi desenvolvido no âmbito do programa de mobilidade de estudantes ERASMUS, no Grupo de Investigação em Redes de Telecomunicações, Departamento de Engenharia de Informação da Universidade de Pisa.