# MUXER--A New Equipment for Energy Saving in Ethernet
## 2 Related Work  
Different kind of use for network equipment, life cycle of energy along with their impact on environment pollution was explained in some work [19]. From a device manufacturer's point of view that, network equipment consumes energy proportional to their usage, their main idea was that devices like routers and switches are power proportional [20].  
Relationship between network parameters and their effect on power consumption during deployment time of network equipment was discussed in another work where some fuzzy logic based approach was used [21]. Local Area Network (LAN) Power management system feasibility was discussed in [PERSON] [22], in their work they tested various elements on LAN switches to sleep in a certain time to reduce power consumption. Similar study about energy management of network switches were performed [23]. Another study in this sector presented two forms of power management schemes to reduce the energy consumption of network. They have shown that simple schemes for sleeping or rate adaptation have significant energy savings without noticeably increased packet loss and latency [24]. Some articles have considered isolated switch are in [25; 26; 27; 28], they have mainly modeled the performance of EEE interfaces.  
In most of current solutions does not consider, describe or modeled the statistical properties of the traffic. Due to this no predictive information is there which could lead us to suitably controlled (activated/deactivated) link state. The examples in this direction are the self-similar features of some Internet traffic [29], and periodic industrial traffic [30]. EEE strategy performance and best way to use EEE approach was also presented in [31].  
There are two manners for energy efficiency in Ethernet: one is to reduce the speed of Ethernet link when there is a little traffic, and another one implements the power-modes to put a network device to sleep and wake it up quickly without a speed change.  
The first one has been first proposed by [PERSON] et al. in 2005 as Adaptive Link Rate [16] and was put in the IEEE 802.3 Ethernet standard. It can be achieved through Autonegotiation, which is used  
Figure 1: Main processes of MUXER.  
to determine the link speed when the Ethernet link is established. This mechanism can reduce the link speed by restarting the Autonegotiation process, and advertising the lower speed to the link [6; 32; 33; 34]. However, the main issue with this approach is that its process takes a long time from a few hundred milliseconds to a few seconds. Rapid physical layer device selection (RPS) is another alternative [18]. It is proposed to accelerate the speed change which is also based on the Autonegotiation process, but does not need to restart this process when agrees a speed change on the links to make a decision on a speed change in a shorter time than previous approach. Although the speed-change mechanisms can decrease the power consumption of the network, but network devices still run continuously that caused the effects of energy efficiency in these mechanisms is not clear when put them into large networks.  
The second manner is the option chosen by the IEEE 802.3 az [35], which has analyzed the mechanisms to support low-power modes for the different Ethernet speeds, such as 100 Mb/s, 1 Gb/s, and 10 Gb/s. This mechanism ensures the receiver of the device in the low-power mode by periodically sending a short period of activity to refresh the receiver's state. It is useful when is applied in asymmetric traffic mechanism, as the link direction which has traffic can be active, while another direction is in low-power mode. However, this standard does not define when to enter or exit the lower power idle mode. This approach also need to change the current protocols in Ethernet.