For the study and verification of our mathematical model of RED-like active traffic management module a discrete simulation model and a continuous analytical model were developed. However, for various reasons, these implementations are not entirely satisfactory. It is necessary to develop a more adequate simulation model, possibly using a different modeling paradigm. In order to modeling of the TCP source, the RED control module, and the process of their interaction it is proposed to use a hybrid (continuous-discrete) approach. For computer implementation of the model the physical modeling language Modelica is used. Because the language Modelica has multiple implementations we have selected the OpenModelica compiler. The hybrid approach allows us to take into account the transitions between different states in the continuous model of the TCP protocol. The hybrid approach simplified the consideration of the model due to the conversion of a differential inclusions into a set of differential equations with discrete transitions. The considered approach allowed to obtain a simple simulation model of interaction between RED module and TCP source. This model has great potential for expansion. It is possible to implement different types of TCP and RED. Furthermore, it is possible to use a hybrid approach not only for the simulation but also for analytical modeling. © ECMS Thorsten Claus, Frank Herrmann, Michael Manitz, Oliver Rose (Editors).