Rule-based topology advertisement supporting generalized protection

Routing in multilayer optical networks can be made efficient if label switched paths are searched in a wavelength graph that represents the state and the switching facilities of the network devices very accurately. Maintaining the wavelength graph by using the conventional link state advertisement control mechanism leads to scalability problem. Much of the link state information is, however, redundant as the set of state changes triggered by a single resource allocation or release are in correlation. By introducing a rule-based topology advertisement and maintenance method, the amount of control messages can be significantly reduced without deteriorating the quality of routing.