Resumen
The Software Defined Networking (SDN) gained recognition due to its improvements at the packet switching and routing layers. The benefits of programmable, remotely controllable networking devices can be applied to the optical layer of contemporary networks as well. This work introduces CESNET's Czech Light~® family of devices and their role in enabling the SDN approach within the CESNET's production network. As a case study, an upgrade of the Cheb node in CESNET's network from a hard-spliced add-drop multiplexers to SDN-capable Reconfigurable Optical Add-Drop Multiplexers (ROADM) is presented. The upgrade improved operational capabilities of the network, including remote channel equalization, and the possibility to deploy new channels or lambdas without physical intervention. The deployment of ROADM also improved the optical properties of the network.