Given the continuous growth of data traffic demand, the optical network management of current infrastructures have become a key factor: Internet pervasiveness has enlarging fast with fiber-to-the-home (FTTH), 5G and future 6G technologies. In the last decade, software-defined network (SDN) concepts has been applied within the optical communication world, making optical networks dynamic and programmable. This has been achieved thanks to the adoption of a single network operative system and the virtualization of the network elements (NEs) forming the physical layer (PHY). The latter can be achieved by means of device disaggregation, vendor-neutral control and multi-vendor inter-operability: Internet service providers and network operators are now interested in these solutions, avoiding vendor lock-in and cutting down on capital expenses.