Abstract. There is a common agreement that virtualization allows more efficient use of the computational and communication resources. In most cases virtualization is used on the operating systems level. Occasionally virtualization is considered on the computer network level. The paper is devoted to the virtualization of the network connections at the Layer 2 and 3 within virtualizers and real devices. For this aim the Xen 4.0 virtualizer is used. VLANs and VLAN in VLAN tunnelling (802.1ad, QinQ) are considered at Layer 2. The static as well as the dynamic routing for the IPv6-in-IPv6 tunnelling are examined at Layer 3. The aim of the paper is to present the implementation of various technologies supporting the network virtualization in the real and virtual environments.