<p>An optical network system (1) includes a multi-bus controller (2) and a plurality of sub-networks (3a to 3n). The multi-bus controller (2) has a layer-3 switch and multiplex (MPX) modules (23a to 23n). The sub-networks (3b to 3n) have optical fibers (61 to 81) connected to multiplexers (32 to 52) and demultiplexers (33 to 53) of the MPX modules (23a to 23n) and optical add-drop multiplex (OADM) modules (62a to 82m) inserted in the middle of the optical fibers (61 to 81). By individually performing wavelength multiplex for each of the sub-networks (3a to 3n) by using the multi-bus controller (2), the optical network (1) enables communication between terminal devices connected to different OADM modules (62a to 82m).</p>
