A system and method in a wavelength division multiplexing passive optical network is provided. A multiplexed optical downstream signal is transmitted from an optical line terminal to a passive distribution node. The signal is demultiplexed into a plurality of optical sub-signals. A sub-signal is transferred to an optical network termination. The received at least one sub-signal is identified. An optical wavelength of an upstream optical signal is set as a function of a predefined relationship between an optical wavelength of the received at least one sub-signal and the optical wavelength of the upstream signal. The upstream signal is transmitted to the optical line terminal via the passive distribution node.