Оцінка адекватності функціонування програмного маршрутизатора у процесі обслуговування мультимедійного трафіку

Abstract

Проведено дослідження імовірнісно-статистичних властивостей трафіку експериментальної мультисервісної телекомунікаційної мережі для підтвердження адекватності моделі програмного маршрутизатора та згенерованого трафіку. Ефективність запропонованого підходу особливо чітко виявляється в умовах значних навантажень на комунікаційне ядро мережі, оскільки навіть незначне зниження затримок потоків реального часу суттєво підвищує якість обслуговування, а в деяких випадках є визначальним фактором для забезпечення оперативності реагування мережевої системи на кризові ситуації. In this paper we perform a study of probabilistic and statistical properties of experimental traffic of multiservice telecommunication network to confirm the adequacy of the developed software router model and simulated traffic profiles. The effectiveness of the proposed approach may be investigated the best under the conditions of significant load on the communication network core, because even a slight reduction in streaming delay substantially increases the service quality, and in some cases it is a major determining factor that ensures the efficiency of the system response on critical situations. The investigations are performed using developed virtual software router. The development was carried under the Qt5.2 programming environment. It uses the programming language C ++ (C ++ standard 11, 2011). The main advantage of this environment is that the code that has been written on it can be compiled on different platforms (e.g. Windows, Linux, Mac OS). Quality control of the traffic generator is performed to determine the maximum rate of IP packets generation with regular inter-packet spacing. The lower the standard deviation of inter-packet spacing, the less error and the more adequate simulation results are observed. We perform a series of tests to determine the quality of generator. Each stage of the experiment isdetermined by different inter-packet spacing and packet size. In the first test the packets flow rate is selected to ensure normal router functioning mode. In each subsequent test the flow rate is increased until the rate value when the length of the emerging queue begins significantly affects the delay of IP packets. Selected The size of software routers incoming buffer is 24 packets. We performed an experiment on comparison of processing delays by hardware router (Cisco 2800 series) and the developed software router to confirm the adequacy of the latter. We have obtained in real time sets of data that are represented as graphs which depict the range of the round trip time for all packets and density of distribution probability. We have used Wireshark network analyzer to fix the fragmentation and grouping of packets in transmitted information flow. Experimental studies have confirmed the adequacy of the results obtained during the simulation of software router. The experiment was performed using 2 and 3 routers for a more accurate assessment of the delay of the real router.