# MUXER--A New Equipment for Energy Saving in Ethernet
## 1 Introduction  
The Internet is rapidly becoming the major consumer of using electricity with measurable impacts. The hubs, switches and routers comprise the core of the Internet in order to guarantee stable and real-time properties at any time. Hence, it causes a large consumption of energy when these devices must be fully activated even if they are in low-traffic conditions for a long time. A report said that the energy consumption of these devices is approximate around 150.4 kilowatt-hour per year (kWh/year) in 2010 [1]. That is the consumption is one Terawatt hours (TWh) per year equivalent to $85 million at $0.085 per kilowatt-hour (kWh) [2] and about 0.75 million tons of CO\({}_{2}\)[3]. Also in 2010, it was estimated that 11 percent of the commercial sector electricity consumption was due to electronic office and telecommunication equipment [1]. In addition to that, all of the network equipment that are connected to the Internet via Ethernet links have link speed range from 100 Mbps to 1 Gbps, eventually up to 10 Gbps and 90 percent of the Internet traffics come in and out on Ethernet ports [4]. The energy consumption of each device in Ethernet is small, but since Ethernet is growing up rapidly, and the overall number of Ethernet-connected devices are also increasing. That is, the total of energy consumption increases in huge amount, as we can see in Table 1[1]. It is estimated that the energy consumption of the Ethernet network devices in the US was approximately 29.7 kWh/year in 2010 [5]. Besides of it, other measurements have shown that, 1 Gbps Ethernet links consume about 4 W more, than 100 Mbps links and 10 Gbps consume even more that is, from 10 to 20 W [6]. Hence, link utilization is the main factor of Ethernet power consumption. A study reported that energy consumption for network switches is 30% [7], among them rack switches are taking 15%, aggregation switches by 10% finally core switches taking 5%. Since devices like processor and drivers are continuously improving their energy saving techniques, but network equipment's energy consumption rate are increasing. There is still opportunity to reduce network energy consumption through energy proportionality. Connected links consume up 65% of the total network power [8] just because they use full power, even if the links are idle [9]. The reduction of CO2 emissions by up to 2.85 million metric tons per year can be saved only in U.S if we can reduce the energy consumption of the network equipment significantly [10]. The Energy Efficient Ethernet (EEE) standard, approved by Institute of Electrical and Electronics Engineers (IEEE) in 2010, improves Ethernet energy proportionality by defining a link sleep mode known as Low Power Idle (LPI). Due to some performance issues some vendors still advise their user to stay away from it until its effect on real application is improving [11; 12; 13]. According to an online source, just to keep network connection stable some devices uses up to 80% of its energy [14]. It also stated that more than 600 TWh of electricity was consumed by such devices in 2013. Some article stated that bandwidth and the number of connections are mostly responsible for energy consumption of Ethernet switch in the usage phase [15]. Currently, there are some approaches that are proposed to overcome Ethernet power consumption. They tried to reduce the use of Ethernet energy by decreasing the link utilization in low traffic conditions or increasing the delay time of MAC frame transactions. Adaptive Link Rate (ALR) [16] or Autonegotiation [17] as a method that switches automatically the data rate of Ethernet full-duplex link to match link utilization. In these approaches, energy savings are achieved by operating at a low link data rate, so that, the network performance, especially packet delay must be in trade-off versus reducing energy consumption. Another approach is IEEE 802.3 az Energy Efficient Ethernet (EEE). The main goal of EEE is to stop transaction when there is no data to send and to resume it quickly when new packets arrive.