Implementing the almost limitless possibilities of a software-defined network requires additional study of its infrastructure level and assessment of the telecommunications aspect. The aim of this study is to develop an analytical model for analyzing the main quality indicators of modern network switches. Based on the general theory of queuing systems and networks, generated functions and Laplace-Stieltjes transforms, a three-phase model of a network switch was developed. Given that, in this case, the relationship between processing steps is not significant, quality indicators were obtained by taking into account the parameters of single-phase networks. This research identified the dependencies of service latency and service time of incoming network packets on load, as well as equations for finding the volume of a switch’s buffer memory with an acceptable probability for message loss.