Simulation of ATM multiplexer for bursty sources

Asynchronous transfer mode ( ATM ) is a promising multiplexing and switching technique for implementing an integrated access as well as transport network and has been adopted by CCITT as a basis for the future broadband integrated services digital network ( BISDN ). The ATM technique allows digital communication of any type to share common transmission links and switching devices on a statistical multiplexing basis. Information is transmitted in the form of constant length cells. In an ATM network, the major parameters to cause ATM network performance deterioration are the cell loss and the cell delay at the buffer queue in the ATM multiplexer. Therefore, the performance parameters of an ATM multiplexer are specifically focused on the cell loss probability, the cell delay, and the distribution of queueing length at buffer m this study. The performance of an ATM multiplexer is studied, whose input consists of the superposition of homogeneous bursty ( ON/OFF ) sources, 1e , all the superposed sources are characterized by the bursty sources of the same parameter values. The cell loss probability and the distribution of queuing length at buffer under different offered load and buffer size conditions are evaluated. An ATM multiplexer with three priority classes is simulated using the priority assignment control method of [15]. Under the priority assignment period P and the priority assignment ratio WD in this method have been defined, the relationship between the traffic balance of classes and buffer size of each is studied. The cell loss probability and delay time of each class ( same sources and different sources between classes ) are evaluated. The results are useful to design a economic and effective ATM multiplexer

Modelos analíticos para la evaluación de mecanismos de control de tráfico en redes ATM

Se presentan una serie de modelos analíticos que son de utilidad para la evaluación de mecanismos de control de tráfico en redes digitales de servicios integrados de alta velocidad que usan conmutación de paquetes. En concreto se estudia el caso de redes ATM (Asynchronous Transfer Mode).Por un lado se ha desarrollado un modelo para evaluar la perturbación que se introduce al multiplexar un flujo individual de tasa constante que tráfico a ráfagas. Por otro lado, se ha estudiado mecanismos que permiten discriminar entre células ATM que ocupan un buffer de memoria en un mutiplexor o conmutador, estableciendo una prioridad de pérdidas.En el desarrollo de los modelos se ha tenido en cuenta las correlaciones que aparecen en los flujos de tráfico de dichas redes. Para ello se han usado modelos markovianos, en los que el estado de una cadena de Markov permite caracterizar la intensidad del tráfico. Los modelos de colas resultantes se han resuelto usando la metodología de análisis matricial de colas desarrollada principalmente por M. F. Neuts y modelos de aproximación de fluido.We study analytical models for the performance evaluation of traffic control mechanisms in high-speed packet switching digital integrated services networks. In particular, we focus our study on the case of ATM networks.The main contributions of this work are two: (i) An analytical model to evaluate the Cell Delay Variation introduced on a CBR flow, and (ii) several analytical models to study Space Priority mechanism, which introduce a priority among cells in the occupancy of multiplexers and switch buffers.These models take into account the traffic correlation present in this type of networks. We have used markovian models, where each state of the Markov chain characterizes the intensity of the traffic. The obtained queueing models where solved using the Matrix Analysis methodology developed by M. F. Neuts, and a fluid-flow approximation