Modelle zur rechnergestützten Simulation von Kommunikationsflüssen in Rechnernetzen

The realization of distributed DP systems requires efficient tools to support the design and analysis of computer network software, taking into account the performance characteristics of the hardware components used. Investigation of the efficiency and correctness of the communication software is of special importance. This work considers the problem of performance evaluation and prediction for computer networks and introduces a set of generalized models which allow detailed description of hierarchically organized communication software and of resource administration within the computer network nodes. Starting from an analysis of computer network structures those model-relevant components of a computer network are first elaborated which form the basis for the introduction of the conceptional models. The conceptional models are mainly formulated as a set of generalized models which can be extended and adapted to different boundary conditions. The fundamental models are the model of a "protocol unit" which allows to describe communication protocols within different (protocol) layers of a hierarchically organized communication software using a common basic model structure, and the model of a "local resource administrator" describing resource management within a computer network node. A simulator (MOSAIC) is introduced, which allows to evaluate experimentally the conceptional models presented. To structure this simulator a concept has been elaborated, which configurates the simulation program dynamically using a set of predefined submodels and being adaptable to cover a large set of different applications. A concept for the interactive execution of simulation experiments is developed, which supports numerous possibilities of interactions during the simulation run and which by means of graphical features offers a comfortable interface to the experimenter. The models have been applied successfully to investigate existing and planned computer networks; some of the experimental results are summarized.