Patent ID: 7616589

Claim:
A virtual LAN creation device for creating a virtual LAN on a network wherein a plurality of nodes are connected, comprising: a topology information storage unit for storing topology information which expresses the topology of the network; a spanning tree creation unit for creating a plurality of spanning trees in reference to the topology information stored in said topology information storage unit, with the spanning tree creation unit counting a number of times each link has been used while the plurality of spanning trees are sequentially created; a spanning tree information storage unit for storing spanning tree information which expresses each of the plurality of spanning trees created by said spanning tree creation unit; a spanning tree selection unit for selecting a spanning tree corresponding to a requested virtual LAN, out of the plurality of spanning trees which are expressed by the spanning tree information stored in said spanning tree information storage unit; a node setup unit for setting spanning tree information stored in said spanning tree information storage unit, and mapping information which expresses the correspondence between the spanning tree selected by said spanning tree selection unit and the requested virtual LAN, in the plurality of nodes; and a link priority setting unit for adding link priority level information, which expresses the priority level of each of the links between the plurality of nodes, to the topology information stored in said topology information storage unit, wherein said spanning tree creation unit creates the plurality of spanning trees in reference to the link priority information until all links are used at least once as elements comprising a spanning tree.