Saving energy in LAN switches: New methods of packet coalescing for Energy Efficient Ethernet

Abstract

Abstract-Small or home office (SOHO) Ethernet LAN switches consume about 8 TWh per year in the U.S. alone. Despite normally low traffic load and numerous periods of idleness, these switches typically stay fully powered-on at all times. With the standardization of Energy Efficient Ethernet (EEE), Ethernet interfaces can be put into a Low Power Idle (LPI) mode during idle periods when there are no packets to transmit. This paper proposes and evaluates a new EEE policy of synchronous coalescing of packets in network hosts and edge routers. This policy provides extended idle periods for all ports of a LAN switch and thus enables energy savings deeper than in the Ethernet PHY only. We evaluate our method using an ns-2 simulation model of a LAN switch. We show that our method can reduce the overall energy use of a LAN switch by about 40%, while introducing limited and controlled effects on typical Internet traffic and TCP.

An experimental power profile of Energy Efficient Ethernet switches

“…In any case, the proposed model would still be valid using different parameters (mostly reducing P base ). On the contrary, if there are actual limitations that make unfeasible a reduction of the power consumption when there is no traffic, then techniques that put the entire switch on a sleep mode such as the one proposed in [19] will provide significant benefits. On the other hand, techniques that only deactivate some of its links will provide insignificant energy savings in EEE switches.…”

“…However, there are many more small switches than large ones, and the aggregated energy consumption of small switches to which users directly connect is significantly higher than for large switches. For example, the power consumption of small Ethernet switches in the US has been recently estimated in 7.9 TWh/year [19]. Small switches typically have 5,8,16 or 24 ports, allowing highly integrated implementations in which only one [20] or a few integrated circuits are used [21].…”

Delay Behavior of On-Off Scheduling: Extending Idle Periods

“…Recent work has focused on how packet coalescing policies for EEE can improve the energy efficiency of Ethernet ( [5,20,23]). At low link utilizations, EEE can be very inefficient when individual packets trigger wake and sleep transitions that exceed the transmission time of the packet.…”

“…Namely, methods studied in [5,23] and deep sleep in EPON ONUs [3] use the first approach, the On/Off-1 algorithm in [12] uses the second approach, and Synchronized coalescing [20] and cyclic sleep in EPON ONUs [3] use the third approach. The first and the second approaches can only be used if coalescer queue state is known.…”

GreenSDN: energy efficiency in software defined networks.

“…-14-10-13-12] SC Conguration tOn(ms) 11 (MOSTOWFI;CHRISTENSEN, 2011) DutyCycle(%) 50 Table 8: Settings of the energy eciency capabilities experiment.…”