Generally, this disclosure describes an energy-efficient Ethernet communications approach. In at least one embodiment described herein, an Ethernet controller may be configured to operate in an active power state to transmit or receive data packets at a maximum available link speed. The maximum available link speed may be determined by a negotiation between the Ethernet controller and a link partner coupled to the Ethernet controller. Once the data packets are transmitted or received, the Ethernet controller may be configured to operate in an idle power state to reduce energy consumption.