Increasing the MTU size for Energy Efficiency in Ethernet

The commonly used Maximum Transfer Unit (MTU) on the Internet has remained unchanged for many years at around 1500 bytes due mainly to backward compatibility issues. This is in contrast with link data rate, which has increased by several orders of magnitude. In this paper, a new advantage of using larger MTUs is introduced, namely Energy Efficiency. In wire-line environments, the link power consumption is generally roughly independent of the number of frames that are transmitted resulting in a poor energy efficiency. This will change with the development of standards like IEEE 802.3az, Energy Efficient Ethernet. This new standard allows a link to enter a low power mode when there are no frames to transmit therefore making power consumption almost proportional to the link load. In this context the use of larger MTUs minimizes the number of transitions between the active and low power modes thereby improving energy efficiency. The benefits of using larger MTUs in terms of energy efficiency are analyzed in this paper.