Implications of energy efficient Ethernet for hubs and switches

The efficient use of energy in communications is an area of growing interest. Until recently energy efficiency received little attention in most wireline communications standards and implementations. In almost all cases, the transmitter and receiver operate at full power, even when no data is being sent. This is the case in most wireline Ethernet standards and results in a considerable waste of energy. Efforts are now underway to develop new standards, such as Energy Efficient Ethernet, with the aim of reducing energy consumption when no data is being transmitted over a link. The changes introduced by Energy Efficient Ethernet have different implications for each network element. The implications for hubs are different to those for switches, for example. These implications are analyzed in this paper. It is shown that the adoption of the new standard will make hubs less energy efficient than switches. This will reinforce the current trend of using switches in new installations. The implications studied in this paper illustrate the potential impact of Energy Efficient Ethernet on Ethernet networks. Other implications, for example on switch implementation and upper layer protocols, can also be expected.