Experimenting Push-Pull Defragmentation in Flexible Optical Networks With Direct Detection
In flexi-grid optical networks, effective defragmentation (i.e., re-optimization) solutions are required to efficiently exploit network spectrum resources. However, current defragmentation solutions can only be implemented thanks to the presence of additional resources, such as spare extensive transponders. In this study, focusing on optically-amplified direct-detection systems, the authors experimentally demonstrate the feasibility of a novel defragmentation technique, called push-pull, based on dynamic light-path frequency retuning upon proper reconfiguration of allocated spectrum resources. The technique does not require additional transponders and does not determine traffic disruption. All the relevant technological limitations that may affect the push-pull applicability are discussed.