Patent ID: 7894441

Claim:
A forwarding device which forwards a packet, comprising: a packet receiving unit which receives a first packet from a port and specifies input source information of the first packet; a routing information unit having routing information of address information and first output destination information corresponding to the address information; a output destination decision unit for searching, based on destination address information included in the first packet, the routing information for first output destination information corresponding to the destination address information; a filtering decision unit for deciding whether or not to execute filtering to the first packet on the basis of the first output destination information; and a filtering execution unit for searching, when the filtering decision unit decides to execute filtering to the first packet, based on source address information included in the first packet, the routing information for second output destination information corresponding to the source address information, wherein the filtering execution unit decides whether or not the second output destination information matches the input source information of the first packet received by the packet receiving unit; wherein, when the filtering decision unit decides that the second output destination information matches the input source information, the filtering execution unit allows forwarding the first packet, whereas, when the filtering decision unit decides that the second output destination information does not match the input source information, the filtering execution unit discards the first packet.