Opportunities and challenges in the network planning of spatially and spectrally elastic optical networks

Spectrally elastic optical networking offers today a well-studied and widely acceptable approach for the allocation of bandwidth varying demands over flexible spectral containers. Its main goal is the optimum use of the available network resources, tailored to the characteristics of the end-to-end network demands. Moreover, the foreseen capacity limitations, due to the continuous increase of traffic volume in networks, led to the adoption of the space dimension, (in addition to the spectrum/wavelength and data format dimensions) for the capacity expansion of future networks. However, space has been mainly considered until today, as a solution for the point-to-point transmission capacity increase, while its potential networking benefits were overlooked, due to the added complexity and the lack of transparent switching elements. The latest advances in novel spatial-spectral switching solutions show that the elastic networking concept can be further expanded over both the spatial and spectral dimensions. This paper provides an overview of the latest developments and possible approaches with respect to elastic optical networking and the emerging benefits that spatially elastic networking approaches can offer. The main focus is on the channel allocation, network planning and resource optimization functions that are possible with the combined use of the spectral and spatial network resources.