NETWORK SYSTEM, NODE DEVICE, AND TRANSMISSION CONTROL METHOD

摘要

PROBLEM TO BE SOLVED: To prevent the hardware scale of a node device from increasing by enabling two-way communication and return communication by using 1st-4th channels which can be discriminated from one another. SOLUTION: A packet A which is transmitted from a terminal 148 connected to a subordinate transmission line 142 of a node device at a transmission source to a terminal V52 connected to a subordinate transmission line V46 of the node device is transmitted in a 1st transmission direction from a variable wavelength transmission part I21 with wavelength λ8 and then sent out in a 2nd transmission direction with wavelength λ6 by a 1st sending-back means of a node device adjoining downstream to the node device at the transmission source. Then the node device as a reception destination converts the packet into a light signal of wavelength λ5 that a fixed- wavelength reception part V outputting the packet to a separation and insertion part V connected to the subordinate transmission line at the reception destination of the node device receives, and the packet after being sent out in the 2nd transmission direction is received by a fixed-wavelength reception part V31 and separated by a separation and insertion part V34; and the signal is transmitted through the subordinate transmission line and received by a terminal V52.