An OLT in a WDM-PON may include a main board and a sub board. The main board may include a master optical transmitting/receiving control/supervising section and the sub board may include a plurality of optical transceivers and a slave optical transmitting/receiving control/supervising section. The master optical transmitting/receiving control/supervising section may produce a data input signal and a data read-control signal for controlling the plurality of optical transceivers of the sub board. The slave optical transmitting/receiving control/supervising section may receive the data input signal and the data read-control signal, and read the data input signal in accordance with the read-control signal. The optical transceivers may be controlled based on the data input signal.