# MUXER--A New Equipment for Energy Saving in Ethernet
## Materials and Methods
### MUXER's Communication
#### 3.4.2 MUXER and Switches  
A MUXER can handle one switch or a group of switches. Communications between MUXER and switches are the main functions of MUXERs. In here, we divide them in four flows: Transferring data signals to switches in normal conditions (4.B1), turning off switches (4.B2), switching data signals from a switch to other switches in the group that are handled by MUXER (4.B3), and turning on switches (4.B4). In case of 4.B1, data signals are sent to ingress ports of MUXER and are transmitted directly to correspondence egress ports. As described in Figure 5, egress port E1 is correspondence with ingress port I1, and (I2, E2), (I3, E3), (I4, E4) are similar. When MAC frames come to I1, I2, I3, I4, they are forwarded to E1, E2, E3, and E4. In case of 4.B2, turning off switches actions must be satisfied with some conditions to guarantee the stability of network topologies, and the minimum probability of loss frames. The first condition is that MUXER must check if there are some data signals come to its ingress ports. As described in  
Figure 4: Flow of data signals when they come to ingress ports of MUXER. Figure 5: MUXER in normal conditions. Section 4, when data signals come into MUXER's ingress ports, ingress ports Ii set their flag bits Fi is one and send these bits to IC Chip. IC Chip receives these bits and uses its counter to count the total data signals for each switch that come to MUXER. After defined several times, with these flag bits, IC chip recognizes which switches don't receive data signals or they receive a number of data signals that are smaller than a defined threshold to satisfy the first condition for generating turning off switches. After MUXER can determine which switches are turned off, it has to check other switches in the group that it is handling if these switches can receive more data signals from others. To guarantee the simplicity of MUXER, in this paper, we base on the number of inactive ingress ports. If the number of inactive ingress ports of other switches that are handled by MUXER is larger than a defined threshold, it means MUXER can switch data signals to these switches. This process is also performed at IC Chip. IC chip checks the flag bits of its ingress ports that are correspondence with each switches. When MUXER recognizes that two above conditions are satisfied, MUXER starts its counter to count down the time for generating turning off signal to switches. At this time, if there are no data signals that come to ingress ports of switches or the time is counted to zero, IC chip of MUXER generates a turn-off signal to its correspondence power port with a switch that is turned off. Power port propagates these signals to the power functions of switches and interrupt the power lines that are supplied for switches. The action flow is described detail in Figures 6 and 7. In case of 4.B3, IC chip of MUXER must have a mechanism to switch data signals from a switch to other switches. A requirement for this mechanism is simplicity. Our approach is based on the electrical mechanism to switch physical circuits. In Figure 8a, in normal conditions, there are the physical circuits between I1 and E1, I2 and E2, I3 and E3, I4 and E4, but when in low traffic conditions, as Figure 8b, switch 1 is turned off, and the physical circuits between I1 and E1, I2 and E2 are dropped, and I1 is connected to E3, I2 is connected to E4. Figure 6: Mechanism of MUXER to turn off and turn on switch. To do that, our research proposes a simple mechanism. Each ingress port has a main circuit to its correspondence egress port. Otherwise, each ingress port also has its additional circuits to other egress ports, so that when an IC chip of MUXER want to switch data signals to any egress port of other switches, IC chip generates control signal to interrupt the main circuit or current circuit of that ingress port, and it generates the control signals to close the circuit of that ingress port and the egress port that MUXER want to transmit data signals of the ingress port to it.