Instruments and Systems: Monitoring, Control, and Diagnostics Annotation << Back Mathematical Modeling of Secure Video Conference Systems by Multilayer Graphs S.A. DRIAGIN, A.S. KORSUNSKII The article deals with the video conference system modeling based on a multilayer graph in order to effectively plan channel capacity for videoconferencing session. A model for a multilayer graph of a video conference system is proposed taking into account the features of building the secure networks, in which several layers of overlay networks are distinguished on top of the transportation network. This model allows taking into account the organization features of each individual layer as well as the rules of traffi c streams between layers. Experiments were carried out to evaluate the session quality based on the PSNR and SSIM indices of objective methods at various videostream parameters, and corresponding quantitative estimates of the required bandwidth to organize a session. Subsequent comparison of the objective method evaluations allows us interpreting its by end-user quality perception criteria. An example for the solution of a problem on searching route with the rules of the overlay network and the actual traffi c fl ow through the transportation network is given. An algorithm is proposed for searching the shortest path in the graph of a secure overlay network with a step-by-step projection of each individual route portion onto the underlying layer of the transportation network for searching the shortest path within its boundaries. The results obtained provide the necessary transmission capacity assessment for videoconferencing session from the view of the requirements to the quality of video images transmitted among session participants. The distribution of the required transmission capacity between the layer of the secured network and the transportation network is presented, taking into account features of the transmission through the intermediate links available between them. Keywords: quality of service, multilayer graph, data transmission system (DTS), videoconferencing (VC), quality evaluation of videoconferencing sessions. DOI: 10.25791/pribor.4.2025.1577 Pp. 45-55.