The study presented in this paper is motivated by the performance analysis of two-server networks with blocking. This model is based on the performance of the Markovian threenode queuing network with finite capacity buffers, for which new and practical results are provided. Here, a two-dimensional state graph is constructed and set of steady-state equations is created. These equations allow for calculating state probabilities for each graph state. The results of investigation allow the definition of the region where the model is useful and where the desired QoS is satisfied.