PURPOSE: To constitute a composite virtual packet exchange network corresponding to each of plural user groups to one physical packet exchange network by constituting multiple virtual packet exchange node with plural virtual packet exchange processing nodes provided with a communication control processor and a node management processor.

CONSTITUTION: A host computer H1 in existence in a physical packet exchange network 30 and terminal equipments S11-S13 are connected to a virtual packet exchange network 10. Moreover, a host computer H2 in existence in the physical packet exchange network 30 and terminal equipments S21-S23 are connected to a virtual packet exchange network 20 and the virtual packet exchange networks 10, 20 are constituted as logically independent packet exchange networks. Furthermore, the physical packet exchange network 30 has 3 packet exchange processing nodes 4, 5, 6, the packet exchange processing nodes 4, 5 are multiple virtual packet exchange processing nodes used in common for the virtual packet exchange networks 10, 20 and the packet exchange processing node 6 is the virtual packet exchange processing node used only for the virtual packet exchange network 20.