On application of least-delay variation problem in ethernet networks using SDN concept

The goal of this paper is to present an application idea of SDN in Smart Grids, particularly, in the area of L2 multicast as defined by IEC 61850-9-2. Authors propose an Integer Linear Formulation (ILP) dealing with a Least-Delay-Variation multicast forwarding problem that has a potential to utilize Ethernet networks in a new way. The proposed ILP formulation is numerically evaluated on random graph topologies and results are compared to a shortest path tree approach that is traditionally a product of Spanning Tree Protocols. Results confirm the correctness of the ILP formulation and illustrate dependency of a solution quality on the selected graph models, especially, in a case of scale-free topologies

Semianalytical Computation of Fourier Series Coeficients

Tato bakalářská práce se zabývá semianalytickým výpočtem koeficientů Fourierovy řady. Cílem práce je vytvořit uživatelské rozhraní pro program TKSL/C. Obsahuje teorii Fourierovy řady a Fourierovy transformace. V další kapitole jsou popsány již existující programy. Dále je navržena vlastní implemetace rozhraní, jsou uvedeny příklady aplikace a shrnuty reakce od uživatelů.This bachelor thesis deals with semianalytical computation of the coefficients of the Fourier series. The aim of this work is to create a graphical user interface for program TKSL/C. The work contains the theory of Fourier series and Fourier transforms. The state of the art software is described in the following chapter. In the next parts the thesis describes the concept of the implementation of the user interface, some tutorial examples which were used and the summary of user testing.

Synthesising TCP data traffic from industrial networks for simulations

In this paper, authors deal with a problem of an impaired TCP stream reconstruction from a real-world captured data. The goal is to obtain an original application data. The data are synthesized to be used as an input for a traffic generator. Authors describe a way to solve specific problems at transport and application layers during the reconstruction of an impaired TCP stream. The traffic reconstruction is oriented to IEC 60870-5-104 protocol on top of TCP. The evaluation of proposed algorithms shows that it is possible to estimate original time dependencies between received and dispatched messages with high accuracy

Impact of nodal centrality measures to robustness in Software-Defined Networking

The paper deals with the network robustness from the perspective of nodal centrality measures and its applicability in Software-Defined Networking (SDN). Traditional graph characteristics have been evolving during the last century, and numerous of less-conventional metrics was introduced trying to bring a new view to some particular graph attributes. New control technologies can finally utilize these metrics but simultaneously show new challenges. SDN brings the fine-grained and nearly online view of the underlying network state which allows to implement an advanced routing and forwarding. In such situation, sophisticated algorithms can be applied utilizing pre-computed network measures. Since in recent version of SDN protocol OpenFlow (OF) has been revived an idea of the fast link failover, the authors in this paper introduce a novel metric, Quality of Alternative Paths centrality (QAP). The QAP value quantifies node surroundings and can be with an advantage utilized in algorithms to indicate more robust paths. The centrality is evaluated using the node-failure simulation at different network topologies in combination with the Quality of Backup centrality measure

Information System Assessment and Proposal for ICT Modification

Tato diplomová práce se zabývá firemním informačním systémem. Hlavním cílem práce je navrhnout opatření na úpravu informačního systému malé společnosti za účelem vylepšení firemních procesů a zvýšení celkové efektivity. Práce je rozdělena do tří částí. V teoretické části jsou popsány nejdůležitější části analýzy informačních systémů. Analytická část odhaluje skutečný stav informačního systému a odhalení chyb, které jsou v následující kapitole řešeny pomocí konkrétních návrhů.This thesis deals with corporate information system. Main aim is to propose measures to adapt the information system of a small company in order to improve business processes and increase overall efficiency. The thesis is separated to three parts. In theoretic part describes the most important section of the analysis of information systems. Analytic part are detected real state and problems and in next part are the recommendations on improvement specific proposals.

Enhancing availability of services using software-defined networking

The immense growth of client requirements imposed on data centre and cloud providers results in a conflict with traditional networking concepts lacking the required agility. In order to promote flexibility, which data centre providers promise to their clients, this discrepancy needs to be resolved, for instance by employing the novel concept of Software-Defined Networking (SDN). This paper utilises this concept in order to minimise service downtime while performing live virtual machine migration. The work is aimed at small/medium-sized data centres and hence the findings are based on real communication patterns found in such environments. Results show that packet loss is slightly diminished while available throughput is increased thanks to the proactive approach taken during network topology changes when compared to the traditional approach based on L2 forwarding

Methodology of the direct measurement of the switching latency

The article provides a measurement methodology based on the related RFCs. It brings a solution of determining the switching latency on the physical layer using common measuring devices. As a proof of concept were done a number of the experimental measurements, including analysis of the results. Switching latency is an important performance parameter which participates in the decision-making whether to deploy the switch to low-latency environments. This is especially important in industrial networks for real-time systems involving smart grids. Determine the value of the switching latency is also an important step in the eventual deployment of the OpenFlow technology on this field.Scopus897635

OpenFlow deployment and concept analysis

Terms such as SDN and OpenFlow (OF) are often used in the research and development of data networks. This paper deals with the analysis of the current state of OpenFlow protocol deployment options as it is the only real representative protocol that enables the implementation of Software Defined Networking outside an academic world. There is introduced an insight into the current state of the OpenFlow specification development at various levels is introduced. The possible limitations associated with this concept in conjunction with the latest version (1.3) of the specification published by ONF are also presented. In the conclusion there presented a demonstrative security application addressing the lack of IPv6 support in real network devices since most of today's switches and controllers support only OF v1.0