Dynamic routing and wavelength assignment scheme for protection against node failure

The problem of how to design a survivable optical network under single and multiple link failures has been studied quite extensively; however, there are few studies on the design of optical networks that could survive single node failures. We design a dynamic wavelength routing scheme that will set up a primary path as well as a node-disjoint shared protection path for each connection using as few wavelength channels as possible by allowing multiple protection paths to share wavelength channels. Sharing full link state information among all network nodes will incur heavy processing overhead and increase routing traffic significantly. We propose a novel scheme that uses three vectors to convey incomplete information of link state. The scheme can be implemented by extending the OSPF protocol. As it is important to network service provider, we also compare the capacity requirement between link failure protection scheme and node failure protection scheme.