Аннотация:This paper is dedicated to the problem of dividingthe physical network into virtual layers with the differentprovided quality of service. Currently, this problem is relevantdue to the development of 5G networks. Our proposed solution— Slicer is a hypervisor with the capabilities to isolate traffic,to automatically map a virtual topology and to provide requiredQoS in a virtual layer. One of the key results of this paper isthe mapping algorithm, that allows to aggregate several physicalswitches into virtual one. To reduce the algorithm complexity theheuristic based on Steiner trees is used in the proposed algorithm.The experimental study of Slicer and our mapping algorithm wasconducted for the topologies from Topology Zoo library.