A method for constructing an optical network includes connecting each of a plurality of nodes in an optical network to an optical switching central node via a set of optical superchannels, wherein each of the optical superchannels includes of a set of subchannels and has a bounded data rate, and wherein the optical switching central node is configured to perform wavelength selective optical switching among the superchannels on a subchannel basis without spectrum contention. Moreover, rearrangement (or “permutation”) of the subchannels of the superchannels connected to the n sites may be performed to minimize the total spectral bandwidth used by the superchannels.