Unique to lightpath computation in WSON is routing and wavelength assignment (RWA). In a WSON without wavelength converters two lightpaths that share a common fiber link can not be assigned the same wavelength. This constraint is referred to as “wavelength continuity” constraint. From the perspective of a carrier path computation functions should support both sequential path computation in which one path computation is done at a time and concurrent path computation in which a set of paths are computed optimally. Distributed path computation may not be suitable for concurrent path computation when the set of paths to be computed have different head-end nodes. This scenario occurs when computing shared backup path computation for a set of independent working paths.