Abstract: A switching method operates with very high-speed wavelength division multiplexing (WDM) links, i.e., with multiple lambdas. An efficient time frame switching method is based on pre-defined switching schedules that are responsive to a global common time reference, where the global common time reference is divided into a plurality of contiguous periodic time frames. The plurality of data packets contained in each of the time frames can be switched from any incoming WDM channel to any subset of outgoing WDM channels. The outcome of this switching method is called fractional lambda switching.