Wyniki wyszukiwania - BazTech

1

Deep data analysis in gigabit passive optical networks

Horvath T., Krkos R., Dubravec L.

Optica Applicata

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2017

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Vol. 47, nr 1

157--170

EN

This paper focuses on practical aspects of gigabit passive optical networks (GPON) diagnostics during deployment, for root-cause analysis and for research purposes. While GPON signalling analysis is already quite commonly used for diagnostics, the aim of this work is a holistic approach, including both signalling and user plane (payload) analysis. User plane analysis, especially if targeted at payload Ethernet, IP and transport layers, enables detection of additional group of problems that could limit or even prevent GPON internetworking and thus degrade the user perceived service quality. Integrated signalling and payload analysis is also interesting from the research point of view, leading to the ability to study equipment idiosyncrasies that would be hard to detect otherwise and it is also one of the enablers of equipment security verification. The mentioned theories were tested during a practical diagnostic session on a real GPON network deployment and this paper presents the findings.

2

Traffic analysis using NetFlow and Python

Oujezsky V., Horvath T.

Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska

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2017

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T. 7, nr 2

5--7

EN

This article presents an application that is used as NetFlow collector and analyzer. It is a console application created in Python language. A software analyzer detects and analyzes incoming NetFlow messages version 1 and 5 of devices that support them. The output file is a database of information and analysis of the overall UNIX time duration of reported traffic and analysis of NetFlow lifetime. The software is developed to work with Python version 3 and higher and is designed for the Windows operating system.

PL

W artykule przedstawiono aplikację używaną jako kolektor i analizator NetFlow. Jest to aplikacja konsoli utworzona w języku Python. Analizator oprogramowania wykrywa i analizuje przychodzące wiadomości NetFlow w wersji 1 i 5 dla urządzeń je obsługujących. Plik wyjściowy to baza danych informacji i analizy ogólnego czasu trwania zgłoszonego ruchu UNIX i analizy życia NetFlow. Oprogramowanie zostało opracowywane dla systemu operacyjnego Windows i języka Python wersja 3 lub wyższa.

3

Novel rogue optical network unit detection algorithm for gigabit passive optical networks

Horvath T., Munster P., Dubravec L., Filka M.

Optica Applicata

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2016

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Vol. 46, nr 3

421--433

EN

Passive optical networks are widely used as a promising solution for future access networks. Currently, the bandwidth is still increasing which means the current copper networks are not able to transfer new services such as 4K video, live streaming, etc. In other words, they reached their capacity limit. The passive optical networks rely on point-to-multipoint technology. That means each customer uses a share medium by time slots. Each time slot exactly specifies who and when is able to transfer data. In general, this control mechanism is implemented in the optical network unit by worst transmission convergence layer. On the other hand, there are cases when the optical network unit (it is called rogue optical network unit) does not follow instructions provided by the optical line termination, for example, if an attacker modifies a firmware of the end unit and/or when the control protocol is not loaded properly inside optical network unit. In worst case, the optical network unit transmits data in a continual mode (other optical network units cannot send data). Thestandard defines finding of the rogue optical network unit but it does not specify how the rogue optical network unit should be allocated because the frames of the rogue optical network unit do not contain the proper parameters. We realized a measurement in a real network with the rogue optical network unit and then we analyzed the captured data. A new algorithm for the rogue optical network unit allocation is presented. We do not consider any modification of the transmission convergence layer in gigabit passive optical networks.

4

Timing measurement and simulation of the activation process in gigabit passive optical networks

Horvath T., Munster P., Jurcik M, Koci L, Filka M.

Optica Applicata

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2015

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Vol. 45, nr 4

459--471

EN

The passive optical networks are widely used nowadays. Service providers have many customers in their distribution networks. The most important thing for communication between the end unit and the control unit is an establishment contact. Design and measurement of the activation process between optical network unit and optical line termination is presented. In general, the service providers have a big split ratio (up to 1:128) due to the connection eminent value of the customers per optical line termination port in chassis. We present the simulation of the connection process for 16, 32, 64, and 128 optical network units and the measurement for single optical network unit (the GPON Xpert is able to read a single connection process). We compare our results in simulation discussion.

5

Distributed Fiber-Optic Sensor for Detection and Localization of Acoustic Vibrations

Sifta R., Munster P., Sysel P., Horvath T., Novotny V., Krajsa O., Filka M.

Metrology and Measurement Systems

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2015

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Vol. 22, nr 1

111--118

EN

A sensing system utilizing a standard optical fiber as a distributed sensor for the detection and localization of mechanical vibrations is presented. Vibrations can be caused by various external factors, like moving people, cars, trains, and other objects producing mechanical vibrations that are sensed by a fiber. In our laboratory we have designed a sensing system based on the Φ-OTDR (phase sensitive Optical Time Domain Reflectometry) using an extremely narrow laser and EDFAs.

6

Quadratic shading and its hardware implementation

Abbas A. M., Szirmay-Kalos L., Horvath T., Foris T.

Machine Graphics and Vision

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2000

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Vol. 9, No. 4

825-839

EN

Rendering systems often represent curved surfaces as a mesh of planar polygons that are shaded to restore a smooth appearance. Gouraud shading uses linear color interpolation and its hardware implementation is relatively easy, but it handles specular highlights incorrectly and introduces annoying artifacts called Mach banding over the edges of the polygon mesh. In software rendering, Phong shading has been more popular, because it can realistically handle specular materials. Since it requires the rendering equation to be evaluated for each pioxel, its hardware support poses problems. This paper presents a nonlinear, i.e. quadratic interpilation scheme which is in between Gouraud shading and Phong shading. It can also be implemented by hardware means as Gouraud shading, but its shading quality is comparable with that of the Phong shading. A software simulation and VHDL description of the shading hardware are also presented.