Dynamically Reconfigurable Transparent Optical Networking Based on Cross-Layer Optimization

Summary form only given. Optical networks evolve towards increased transparency in the physical layer and more intelligence in the control and management plane. However, operating a dynamically reconfigurable transparent mesh optical network is extremely challenging. The network designer has to deal with a number of challenging issues like a) the accumulation of signal impairments that deteriorate the signal quality and b) the inability to locate network element failures in order to provide efficient network restoration. To overcome the problems caused by the impairments at the physical layer, dynamic impairment management techniques may be implemented in-line (e.g. optical means of impairment compensation) or at the optical transponder interfaces (e.g. electronic mitigation of impairments). From the network layer view, the implementation of certain RWA algorithms that consider signal impairments and constraint the routing of wavelength channels according to the physical characteristics of the optical network paths can further improve the performance and minimize the blocking probability of connection requests. These algorithms are reported in the literature as Impairment Constraint Based Routing (ICBR) algorithms and ensure that connections are feasible to be established considering not only the network conditions (connectivity, capacity availability etc) but also the equally important physical performance of the connections. The impairment constraint routing algorithms can be also further improved by performing impairment constraint wavelength assignment. By selecting portions of the spectrum with minimal impairments, increasing the wavelength spacing in these spectral regions, and giving preferential signal-to-noise- ratio treatment to these wavelengths within the optical amplifiers and switches, true end-to-end transparency may be attainable. The resend progress in the field of dynamically reconfigurable transparent optical networking based on cross-layer optimi- zation will be reviewed and future potential advancements will be analyzed.