Patent ID: 7529240

Claim:
A transmission device for configuring a ring or cascade type communication network which includes two or more transmission devices and is used in such a form of each of said transmission devices being connected to a specified network, comprising: a first storage unit that stores a multicast address of each multicast packet that should be transmitted onto said network connected to said transmission device; a multicast packet receiving unit that receives a multicast packet where discard condition information is set, which is transmitted to said other transmission device; a multicast packet drop unit that transmit, as far as the multicast address set in the multicast packet received by said multicast packet receiving unit is coincident with any one of multicast addresses stored in said first storage unit, the multicast packet onto said network connected to said transmission device; a multicast packet transferring unit that transfers, if the discard condition information set in the multicast packet received by said multicast packet receiving unit does not indicate discarding by said transmission device, the multicast packet to said next transmission device, and discarding, if the discard condition information set in the multicast packet received by said multicast packet receiving unit indicates discarding by said transmission device, the multicast packet without transferring the multicast packet to said next transmission device; a second storage unit that stores architecture information showing an arrangement sequence of said plurality of transmission devices configuring said communication network, and all the multicast addresses stored in said first storage unit with respect to said respective transmission devices; an information updating unit that executes a process of updating most the multicast address stored in said second storage unit with respect to each of said transmission devices; and a multicast packet transmitting unit that specifies based on the information stored in said second storage unit, when the multicast packet is transmitted from the host on the network connected to said transmission device, said transmission device having no necessity of transferring the multicast packet to said next transmission device, and transmitting to said next transmission device the multicast packet in which to set discard condition information from which said multicast packet transferring unit of said specified transmission device judges that the multicast packet be indicated to be discarded by said transmission device.