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.
This paper proposes an extension to the method to be able to handle various protection
schemes in the network simultaneously. Although the proposed method is primarily developed
for optical networks and Wavelength Graphs it can be applied efficiently also onto
pure MPLS networks.
