1. An apparatus comprising: a plurality of wavelength division multiplexing access nodes of an optical network employing a source based scheme to establish communication paths, each of said plurality of access nodes building and maintaining a set of one or more network topology databases specific to that access node based on a set of one or more connectivity constraints, wherein a network topology database includes a representation of a plurality of paths and wavelengths thereon of possible communication paths from that access node to other nodes, wherein each path is a series of two or more nodes and links interconnecting them through which traffic is carried, wherein the wavelengths for each path are the set of wavelengths of each link of that path that are available for establishing lightpaths on that path, and wherein said building and maintaining the set of one or more network topology databases includes building and maintaining the representation of the plurality of paths of the possible communication paths in each of the set of one or more network topology databases, and each of the plurality of access nodes selecting and allocating requested communication paths from the plurality of paths having that access node as a source, wherein that access node marks as allocated other communication paths from the plurality of paths that have a link and wavelength thereon in common with the requested communications paths, wherein the marking is in response to the selecting and allocating the requested communication paths.