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Energy efficient network methods on local area network Emir Husni, Aska Narendra School of Electrical Engineering & Informatics, Institut Teknologi Bandung Jl. Ganesha no. 10 Bandung, Indonesia
[email protected] Abstract: Energy consumption is an issue that is currently often complained of by many households and offices. One of the equipments that take a lot of energy is the computer. Computer usage has been growing rapidly. However, in addition to energy issues, network quality is often questioned. Here, delay tolerant network (DTN) is used for maintaining data reliability even the receiver is off to saving the energy. In addition, the techniques used tested on a lab-scale network testbed. The final results obtained demonstrate the success for 60.513% energy savings when compared with the normal use of the testbed. Keywords: energy; network; LAN; delay tolerant network; energy saving; router; proxy.
1 Introduction Along with technological development, more and more new technologies are introduced by the famous computer entrepreneur to market their products to the public. In addition, the curiosity of the technology was also spread to various parts of the world (Aputis, 2007)(Lemma et al.)(Matthee et al.). Society became more open to technological developments, so they began to choose technology that suits your lifestyle. A lifestyle that is now increasingly in demand by the public is a lifestyle "go green", which is a lifestyle that minimizes the use of energy sources or objects that could damage the environment as plastic waste that is difficult to unravel, the use of air conditioner (AC), or excessive consumption of electrical energy. Still, not everyone is aware of the importance of saving energy. With increasingly advanced technology, more and more people are living depends on the Internet. High level of market demand led to a service provider provides continuous service without interruption. In addition to its dependence on the internet, many people have a lifestyle that is dependent on the computer. Many people choose to turn on his computer 24 hours continuously. This is usually caused by a tolerance for low waiting time; so many people choose to turn the computer on an ongoing basis compared to having to wait turn on the computer. Therefore, the required energy saving techniques that can be implemented easily by everyone so that even turn on in a long time, energy consumption can be saved. A drawback of the computer is that the energy needed to run it is high. In addition, the use of the computer continuously without a break causes increased energy usage. In the regular network, there are several components, such as server or router, must be turned on constantly to maximizing network services. Therefore, more and more emerging methods come for the use of network components that are energy efficient or minimize the use of energy without degrading the quality of network services (Cuomo et al., 2011). Here, delay tolerant network (DTN) is proposed to be used in the energy efficient network. DTN is a network architecture that is devoted to network with a high level of fault and long variable delay (Ayari et al., 2008)( DTNRG, 2012)(Warthman, 2003). The goal of the use of the DTN is that in spite of the energy efficient network, the performance is not decreased. Therefore, DTN techniques to build the energy efficient network without losing the performance are studied here.
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2 Theory There are four important elements in building this system, they are energy efficient network, delay tolerant network, local area network, and router. 2.1 Energy Efficient Network
Energy Efficient Network is a term for a computer network architecture that requires less energy usage when compared with the network in general. This type of network is to saving the use of energy to run the network components, without reducing the effectiveness of the overall network (Banerjee et al.)( Cuomo et al., 2011)( Gupta & Singh, 2007). Currently, the energy savings in the network can be broadly applied through three techniques, namely: • Link change rate, • Proxying, • Energy efficient Delay Tolerant Network. 2.2 Delay Tolerant Network
Delay Tolerant Network is a term for networks that are designed to deal with end-to-end connectivity issues on certain networks, especially networks of heterogeneous computers (DTNRG, 2012)(Warthman, 2003). Connectivity issues in question here is mainly related to the continuity of data between the computer end-to-end (Fall). Examples of the network that goes into this category are underwater networks, military, or the network in places that are still underdeveloped technology grows in such remote areas. DTN overcomes the problems associated with intermittent connectivity, long or variable delay, asymmetric data rates, and high error rates by using store-and-forward message switching. The key idea is to facilitate opportunistic transport on a hop-by-hop basis rather than end-to-end streaming of data as in TCP/IP. Every node in DTN has storage and every packet is stored from one node to the next node if the connection is available until all packets are sent from the source to the destination, as illustrated in Figure 1. NODE A
store
NODE B
forward
store
forward
NODE C
store
NODE D
store
forward
Figure 1 Store-and-forward mechanism
DTN method will be suitable for energy efficient network because every node in the network will store the data transmitted untill the destination is on. The method used in energy efficient network is to make every node is on and off based on the schedule. This on-off method will reduce the energy usage. Basically, the main techniques used to build a delay-tolerant network is routing (Jain et al.). In addition, there are several other techniques that can support the formation of DTN networks such as proxying. 2.3 Local Area Network
Local Area Network (LAN) is connected by a network of media networks that are within a limited area such as home, office, or school. In general, a LAN network with a small scale, so the number of nodes on the network, either routing node and user node bit. Along with the growing number of Internet users in the world, the use of IP addresses even more bertambah.cara to overcome these problems is to use Private IP address. Private IP is the IP address allocated specifically for use in a specific network environment that can not be used as an address that can be detected by NAT as a private address. In addition to the IP address, a LAN network must also consider the network topology. To build an effective LAN network, must use the appropriate topology for the data transfer to be effective and
efficient (Lai, 2011). Some commonly used topology is a star in the LAN, line, bus, ring, and tree. Topologies can be seen for example in Figure 2.
Figure 2 Various network topology 2.4 Router
Router is a component in a network that serves as a successor to the data packets flowing in the network that sent correctly from the sender to the destination (Donahue, 2007). Router works by utilizing the routing table belongs to the network or the router itself to determine the best path to send data packets. On a dedicated router made by a factory in general, the firmware used is the factory’s firmware. It can provide the drawback since the firmware has limited functionality. Therefore, today there are many network administrators start using third party firmwares for their routers because they are more complete and easier to be configured according to network conditions. Third party firmwares that are commonly used are: OpenWRT, DD-WRT, and tomato. In this paper, the OpenWRT firmware was used. the GUI’s display can be seen in Figure 3.
Figure 3 GUI of OpenWRT
3 Experiment Design 3.1 Testbed
Here, the summary of the testbed used in this paper is explained. The equipments used in this testbed include: 1. Router Linksys WRT54GL with OpenWRT firmware, 2. Notebook, 3. Desktop computers, 4. UTP cable, 5. Digital kWh meter. On notebooks and computers, the schedule is given for sleep when the computer or notebook is not doing anything in a while to save energy. In this case, computers and notebooks are scheduled to sleep at 5 pm to simulate the non-active computer or notebook after work hours. On the router, the configuration is given to hold incoming packets at the destination node is in a state of sleep. In addition, the router is also scheduled to wake the notebooks and the computers at 8
o'clock to simulate the start of working hours. All devices connected to a voltage source through a kWh meter testbed so that that energy use can be recorded. The LAN network topology used by this testbed is a star topology. Star topology is used because it is the topology which has the best connectivity and fewer components required for network architecture than other topologies. The architecture of this testbed can be illustrated in Figure 4 below. 240v kWh meter digital
Laptop
INTERNET Router
Komputer
Figure 4 Architecture of the testbed 3.2 DTN Test
The DTN test will use a line topology. The architecture of the testbed is shown in Figure 5. Router Node 1
Node 2
Figure 5 Testbed in line topology
In this test, node 1 will send the data in the form of a ping to node 2 at the time in a state of sleep. If successful, despite being sleep, node 2 still gives a response. Next, node 2 will be put into sleep mode and the data in the form of a message is sent by node 1. After the lapse of time, node 2 will be raised and if node 2 received a message and gives the response after waking up, then the test is successful. With this test, will be able to be seen whether the system is prepared in a DTN router can work well if the node is in sleep state or disconnected from the router. Here, the router is doing the greatest role of having to handle the data packets coming from the outside and held in the router if the destination node can not be achieved. 3.3 Energy Usage Tests
This test was performed to test the amount of energy saved by energy saving method. This test will use a star topology. This testing will be done in three schemes. In each scheme, the energy usage will be recorded via digital kWh meter. The results of average energy of each scheme will be taken and used for the analysis of the results. Final output of the analysis is the presentation of the results of energy saving schemes, and the percentage of energy saving for a day. 1) Scheme 1: The first scheme is to use a normal testbed for 1 hour. In this scheme, all the components in the network will be on continuously to simulate the normal network usage activity for a certain time. The experiment was conducted 10 times, where in each trial will run for 1 hour. The results of ten experiments will then be searched on average values, which are then used to analyze the results. 2) Scheme 2: The second scheme is to use the testbed with energy saving scheme for 1 hour. This energy saving schemes in other words is a condition in which all these tools in a state of low or moderate power to save energy. Same as scheme 1, scheme 2 will be tested for 1 hour 10 times. The results of each experiment and then to search the average value, which will then be used to analyse the results.
3) Scheme 3: Scheme 3 is to use the testbed to normal for 1 hour, and to make energy saving schemes for 2 hours. Comparison of time is used to simulate the use of computers during working hours, ie 8 hours, and then rested in energy saving mode for the rest of the day, ie 16 hours, so we get the comparison with the normal use of energy savings 8:16, or if reduced to 1:2 . Because this scheme needs to be done for 3 hours total, then the experiment will only be performed 5 times to save time. The results of each experiment and then to search the average value, and also sought an average value per hour which will then be used to analyse the results.
4 Results and Analysis 4.1 DTN Test
In this test, node 2 successfully receives a packet from node 1 after raised. In the ping experiment, node 2 can reply to node 2 after receiving data. These results can be seen in Figure 6.
Gambar 6 Hasil pengujian ping DTN
In the IM test, node 2 managed to get a message from node 1 after node 2 is turned on back. These results prove that the DTN system is working properly. 4.2 Energy Usage Tests
The next experiment is testing the energy consumption. Before conducting the experiment, it is important to know the energy used by each component. This can be done by using digital kWh meter. The results of this experiment are presented in Table 1. Table 1 Energy usage of every component on the testbed Lowest
Stable
Peak
Router
5
6-7
8
Notebook (normal)
20
33-37
49
Notebook (sleep) Computer (normal)
1-2 66
Computer (sleep) Testbed (normal) Testbed (sleep)
70-80
89
6 98
114-122
150
13-14
The results of schemes 1, 2, and 3 respectively can be seen in Table 2-4 below.
Table 2 Energy usage of the testbed for scheme 1 Scheme 1
Average per hour
Test 1
0,13
0,13
Test 2
0,12
0,12
Test 3
0,14
0,14
Test 4
0,14
0,14
Test 5
0,12
0,12
Test 6
0,13
0,13
Test 7
0,13
0,13
Test 8
0,12
0,12
Test 9
0,13
0,13
Test 10
0,14
0,14
Average
0,130
0,130
Table 3 Energy usage of the testbed for scheme 2 Scheme 2
Average per hour
Test 1
0,01
0,01
Test 2
0,01
0,01
Test 3
0,02
0,02
Test 4
0,01
0,01
Test 5
0,01
0,01
Test 6
0,01
0,01
Test 7
0,02
0,02
Test 8
0,01
0,01
Test 9
0,01
0,01
Test 10
0,02
0,02
Average
0,013
0,013
Table 4 Energy usage of the testbed for scheme 3 Scheme 3
Average per hour
Test 1
0,14
0,0467
Test 2
0,16
0,0533
Test 3
0,16
0,0533
Test 4
0,15
0,05
Test 5
0,16
0,0533
Average
0,154
0,0513
From the test results can be seen, the average energy use of schemes 1, 2, and 3 per hour, respectively 0.130, 0.013, and 0.0513 kWh. From this result shows that scheme 3 has a value of scheme
1 to scheme 2. This proves that scheme 3 has a good energy saving capabilities. When compared, the amount of energy saved between normal use of the testbed with the use of energy saving systems are
0.13 − 0.013 × 100% = 90% . 0.13 If the experiments 1 and 2 multiplied by 24 then the result is 3.12 and 0.312 kWh. Because 3 is an experimental trial with a duration of 3 hours, then to represent the results in 24 hours, the results of experiment 3 will be multiplied by 8 and the result is 1.232 kWh, or by multiplying the hourly average of 24 is 0.05133 with a similar result is 1.232 kWh. So, if we let a local network of standardized switched on for 24 hours continuously, the testbed will use the energy as much as 3.12 kWh. If you use this energy savings scheme, by letting the use of computers in accordance with standard working hours, which is on for 8 hours and off for 16 hours, the energy used is equal to 1.232 kWh. By taking the above data, it obtained the energy consumption savings for a local network using this energy savings scheme (scheme 2), which can be seen in the following calculation.
3.12 − 1.232 × 100% = 60.513% . 3.12 4.3 Analisis Model Keseluruhan
The model used in this testbed largely complies with the original purpose of this research. DTN on a testbed system can work well and can save more than 60% energy in a similar manner while maintaining connectivity to the network computer. As a comparison, let's say the use of energy savings by turning off all the appliance. That means, for 8 hours appliance is turned on, and the appliance is turned off for 16 hours. To represent that state, then use a scheme, which is normal usage scheme multiplied by 8, which is 1.04 kWh. For 16 hours of rest, because it is turned off, the energy used is 0, so the total energy usage in the last 24 hours in this scheme is 1.04 kWh. From these figures, the percentage of energy savings obtained as follows.
3.12 − 1.04 × 100% = 66.667% . 3.12 It appears that the scheme lethal tools, energy savings amounted to 66.667% of this value only slightly different than if you use the energy saving scheme. This means, simply by taking a little extra energy, connectivity and network presence in a network can be maintained. This model can provide a great advantage in different types of users. As an example, an office worker may prefer to store data on your office computer job. However, if the worker has to take data remotely, it would be difficult for him if the computer is turned off, and would be wasteful of electricity if the computer keeps bringing it up. This model can solve these problems. However, this model is still an early model for the research theme of saving energy in DTN. There are still many shortcomings that may exist in this model, so this study can still be developed for future.
5 Conclusion From the results of studies and experiments, obtained the following conclusions. To build energy-efficient DTN system, required the selection of the proper technique. This is because not all methods of energy utilization to increase or maintain the connectivity required by the DTN, and not all the DTN architecture can be formed to be more efficient in energy use. In addition, not all of DTN and energy saving techniques suitable for the local network. By using this energy savings scheme, the energy can be saved in one day reach 1.888 kWh or 60.513% of the regular energy usage without sacrificing the network connection.
Energy savings in the network can be implemented through three techniques, namely: • Changes in rate link • proxying • Energy efficiency specification. For DTN, a technique that can be used appropriately is proxying. This causes the proxying technique becomes the most important techniques in making DTN a energy-saving system because the technique is able to meet the needs of DTN system or energy saving.
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