Spectrum defragmentation implementation based on software defined networking (SDN) in flexi-grid optical networks

OFDM has been considered as a promising candidate for future high-speed optical transmission technology. Based on OFDM, a novel architecture named flexi-grid optical network has been proposed, and it has drawn increasing attention in both academic and industry. In flexi-grid optical networks, with connection setting up and tearing down, the spectrum resources are separated into small non-contiguous spectrum bands, which may lead to inefficient spectrum utilization. The key requirement is spectrum defragmentation, which refers to periodically reconfigure the network and return it to its optimal states. Spectrum defragmentation should be operated under minimum cost including interrupting services or affecting the QoS (i.e. delay, bandwidth, bitrate). In this paper, we demonstrate for the first time spectrum defragmentation based on software defined networking (SDN) in flexi-grid optical networks. Experimental results are reported on our testbed and verify the feasibility of our proposed architecture.