A method of establishing a data connection between terminal switching nodes in a network involves switching nodes participating in a network layer wavelength routing (WR) protocol to determine the next hop switching node for every possible combination of terminal nodes based on the network topology. Switching nodes participate in a network layer wavelength distribution (WD) once the data connection is to be established. The WR protocol determines the path used through the network, while the WD protocol assigns wavelengths on each link between switching nodes. The wavelengths may be different on different optical links. The switching nodes include wavelength converters with an optical switch or optoelectronic converters with a digital electronic switch. Advantages of using potentially different wavelengths along various segments of a single end-to-end connection yields increased wavelength efficiency.