In a virtual network construction method, a virtual network construction system, and a relaying apparatus within a public data communication network, control packets each having set a multicast address are multicast, and upon reception of the control packets by the relaying apparatuses belonging to the...http://www.google.de/patents/US20020067725?utm_source=gb-gplus-sharePatent US20020067725 - Virtual network construction method, system, and relaying apparatus
