Patent ID: 8325645

Claim:
A network relay apparatus connecting with a network, the network relay apparatus comprising: a relay apparatus selector configured to, in response to direct or indirect reception of a join request for a preset multicast group from an external device connecting with the network, refer to information for identifying respective network relay apparatuses on a segment which the own network relay apparatus belongs to, and, at least one of information for identifying the preset multicast group and information for identifying a source, wherein the information for identifying the preset multicast group and the information for identifying a source are included in the received join request, and unequivocally select one network relay apparatus among at least part of the network relay apparatuses on the segment as a designated network relay apparatus according to a predetermined rule, wherein the designated network relay apparatus is assigned to relay a multicast packet to the external device; and a setter configured, when the own network relay apparatus is selected as the designated network relay apparatus by the relay apparatus selector, to set a multicast route for relaying the multicast packet to the external device, and when the own network relay apparatus is not selected as the designated relay apparatus by the relay apparatus selector, not to set the multicast route for relaying the multicast packet to the external device, wherein, upon detection of addition of another network relay apparatus on the segment, the relay apparatus selector is configured to refer to: information for identifying respective network relay apparatuses on the segment including the added network relay apparatus, and at least one of information for identifying a multicast group which the external device participates in and information for identifying a source of delivering a multicast packet to be sent to the external device; and to select again one network relay apparatus among all the network relay apparatuses on the segment including the added network relay apparatus, as the designated network relay apparatus assigned to relay the multicast packet to the external device.