This Recommendation defines the integration of green abstraction layer [ETSI ES 203 237] into a software-defined networking (SDN) architecture [ITU-T Y.3302]. Four basic SDN elements are defined within the SDN architecture [ITU-T Y.3302]: the SDN application layer@ the SDN control layer@ the northbound interface between the SDN application layer and the SDN control layer and the southbound interface between the SDN control layer and the SDN resource layer. The green abstraction layer adds a further dimension which requires integration and is the subject of this Recommendation. Since the green abstraction layer allows applications to access to the power management capabilities of network nodes in the resource layer to effectively adapt the energy consumption of the network nodes with respect to the load variations@ it can be said that all the SDN elements are impacted. In this respect@ this Recommendation focuses on: ?C The definition of an energy-efficient SDN general architecture; ?C The definition of an energy states model. Appendix I provides an example of an energy-efficient SDN based on the Open Networking Foundation (ONF) specification [b-ONF-SDN].