Impairment-Aware Control Plane Architectures to Handle Optical Networks of the Future

In transparent (and translucent) optical networks, physical layer impairments (PLIs) incurred by nonideal optical transmission media accumulate along an optical path, and the overall effect determines the feasibility of the lightpaths. If the received signal quality is not within the receiver sensitivity threshold, the receiver may not be able to correctly detect the optical signal, and this may result in high bit-error rates. Introducing optical transparency in the physical layer reduces the possibility of client layer interaction with the optical layer at intermediate nodes along the path. The standard GMPLS protocols used for dynamic establishment of lightpaths in transparent/translucent optical networks suffer from lack of PLI information and optical component characteristics. Hence, there is a strong need for development of techniques that provide PLI information to GMPLS protocols and mechanisms that use this information efficiently to evaluate optical feasibility of lightpaths. Without the development of such mechanisms, it would be impossible to automatically initiate a lightpath establishment from client layers, for example, switch or an IP router or a label switch router (LSR). In this chapter, various impairment-aware optical control plane (IA-OCP) approaches are described and compared, namely, signaling-based approach, routing-based approach, hybrid approach, and PCE-based approach. The properties of these control plane architectures are qualitatively studied. Furthermore, the performance study of two IA-OCP approaches is discussed through extensive simulation results.