Optical Networking Best Practices Handbook

1.4. LIGHTPATH ESTABLISHMENT AND PROTECTION IN OPTICAL NETWORKS

Optical networking technology that provides multiple wavelengths on a fiber has the capability of offering an infrastructure for the next-generation Internet. A promising approach for building an optical network is that a logical network consisting of the wavelength channels (lightpaths) is built on the physical optical network. Then, IP traffic is carried on the logical topology by utilizing the multiple protocol lambda switching (MPLS) or generalized MPLS (GMPLS) technologies for packet routing. An important feature that the optical network can provide to the IP layer is a reliability function. IP has its own routing protocol, which can find a detour and then restore the IP traffic upon a failure of the network component, but it takes a long time (typically 30 s for routing table update). In contrast, a reliability mechanism provided by the optical network layer can offer much faster failure recovery. It is important in a very high-speed network, such as optical networks, since a large amount of IP traffic is lost upon a failure occurrence in such a network [4].

Backup paths as well as primary paths are embedded within the logical topology when constructing the optical network with protection. The two protection mechanisms presented here for discussion are dedicated and shared protection methods. The dedicated protection method prepares a dedicated backup path for every primary path. However, in the shared protection ...