Packet communication method

A packet communication method using a plurality of packet transfer apparatuses which are connected to a network and transfer a lower layer frame containing an encapsulated upper layer packet, at least one frame transfer apparatus which mediates transfer of the lower layer frame between the packet transfer apparatuses through the network, and a network control server which is connected to the packet transfer apparatuses and the frame transfer apparatus and controls a communication route of the lower layer frame in the network by giving an instruction to the packet transfer apparatuses and the frame transfer apparatus, characterized in that

• the packet transfer apparatus comprises
• an extraction procedure which extracts, from the received lower layer frame, a lower layer address pair including a transmission source address and destination address of a lower layer,
• a first registration procedure which registers a sending destination of the received lower layer frame in a first table for each corresponding destination address,
• a first counter procedure which counts, for each type of lower layer address pair, a quantity of the lower layer address pair extracted by the extraction procedure, and
• a first transmission procedure which transmits, to the frame transfer apparatus, first information representing the lower layer address pair counted by the first counter procedure beyond a predetermined threshold value within a predetermined time,
• the frame transfer apparatus comprises
• a second registration procedure which registers a transfer destination of the received lower layer frame in a second table for each destination address contained in the lower layer frame,
• a second counter procedure which counts a quantity of the transferred lower layer frame for each type of lower layer address pair contained in the first information received from the packet transfer apparatus, and
• a second transmission procedure which transmits, to the network control server, second information about the lower layer address pair counted by the second counter procedure beyond a predetermined threshold value within a predetermined time, and
• the network control server comprises
• a calculation procedure which, upon receiving the second information, extracts the transmission source address and destination address from the second information and executes calculation to optimize the communication route in the network between the transmission source address and the destination address, and
• a change procedure which changes registration of the sending destination of the lower layer frame registered in the first table and second table on the basis of the calculation result.