A vectored fragmentation metric for elastic optical networks

When circuits are set up and dismantled dynamically in elastic optical networks, the link spectrum becomes fragmented. The fragmentation limits the available path choices and may lead to significant blocking of connection requests. The fragmentation can be link fragmentation due to non-contiguity of available spectral resources on individual links or path fragmentation due to non-continuity of available spectral resources on the paths of the connection requests. The study of fragmentation and its management is essential to operate the networks efficiently. This paper proposes a vectored fragmentation metric for characterizing the fragmentation, which includes both types of fragmentation. We discuss the characteristics of this metric considering different network scenarios, where connection requests arrive and depart dynamically. To establish the functionality of this metric, we also test the utility of the metric in fragmentation management cases. We compare the different link-based fragmentation metrics and a path-based fragmentation metric with our Adapted vectored fragmentation metric to understand the efficacy of the proposed measure. We find the vectored fragmentation metric to be effective in this study.