Patent ID: 8085795

Claim:
A packet relay apparatus connecting a sub-network accommodated by the apparatus itself to a global network, grouping terminals within the sub-network virtually and building up a virtual private network by an intra-group member communication that is a communication between members within a group made by a grouping of the terminals, comprising: a first storage unit which stores routing information for use in an intra-group member communication relating to a main route and a sub-route, of a first Internet protocol (IP) packet and a second IP packet, and route identification information for identifying an event of being transferred by way of the main route and the sub-route, wherein the first IP packet is managed by an internal management transfer number for identifying the main route used for the intra-group member communication, a sub internal management transfer number for identifying the sub-route used for the intra-group member communication, a transfer number for identifying a transfer route of the first IP packet which is transferred to another packet relay apparatus on the global network and a group number for identifying a group, and the second IP packet is transmitted and received to and from a terminal under a control of the apparatus itself; an information management unit which sets and updates the routing information and the route identification information stored in the first storage unit; a first transmission/reception unit which transmits and receives the second IP packet between itself and the terminal under the control of the apparatus itself; a first packet creation unit which creates the first IP packet by adding an inter-packet relay apparatus header to the second IP packet received by the first transmission/reception unit by referring to the routing information and the route identification information which are stored in the first storage unit, the inter-packet relay apparatus header including information related to the main route, the route identification information and a packet identification information for identifying a packet; a second transmission/reception unit which transmits the first IP packet created by the first packet creation unit to another packet relay apparatus by referring to the routing information and route identification information which are stored in the first storage unit and also receives the first IP packet created by the first packet creation unit of another packet relay apparatus and addressed to a terminal under a control of the apparatus itself; and a second packet creation unit which creates the second IP packet by deleting the inter-packet relay apparatus header from the first IP packet received by the second transmission/reception unit and outputs the second IP packet to the first transmission/reception unit.