PURPOSE: To eliminate an active switch and to extract a signal to a self-node by obtaining the respectively different wavelength of a burst whose transmitting destination node is different and multiplexing the burst sent from the respective nodes when the are observed to be horizontally arranged at a arbitrary time.

CONSTITUTION: An electric signal from an electric interface 2 is converted to an optical signal to satisfy the two points of conditions (a) and (b) by an electric optical converting circuit 3. As the circuit 3, an element to be able to hourly oscillating wavelength control is used. The condition (a) is to hourly control an optical wavelength allocated to respective bursts cyclicly sent at every transmission destination node from respective transmission source nodes so that they can be different at every transmission destination node. The condition (b) is to hourly execute the cyclic control of the transmission destination node of the respective bursts cyclicly sent per transmission destination node from the respective transmission source nodes so that they can be always different mutually when they are observed to be horizontally arranged between the respective tramsmission source nodes at an arbitrary time.