When a packet transfer equipment receives a packet, it extracts several types of information contained in the received packet such as the destination IP address and the destination port number and, using the extracted information as the key, inquires of a packet transfer method resolution server about the information related to the packet transfer method. The server keeps the correspondences between several types of information contained in the packet and one or more type of information related to the packet transfer method in the database and, in response to the inquiry from the packet transfer equipment, replies one or more type of information related to the packet transfer method. The packet transfer equipment rewrites several types of information such as the destination IP address and the destination port number according to one or more type of information obtained and transfers the received packet.