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Reducing the Energy Consumption of Ethernet with Adaptive Link Rate (ALR)
April 2008 (vol. 57 no. 4)
pp. 448-461
Rapidly increasing energy consumption by computing and communications equipment is a significant economic and environmental problem that needs to be addressed. Ethernet network interface controllers (NICs) consume hundreds of millions of US dollars in electricity per year. Most Ethernet links are underutilized and link energy consumption can be reduced by operating at a lower data rate. In this paper, we investigate Adaptive Link Rate (ALR) as a means of reducing the energy consumption of a typical Ethernet link by adaptively varying the link data rate in response to utilization. Policies to determine when to change the link data rate are studied. Simple policies that use output buffer queue length thresholds and fine-grain utilization monitoring are shown to be effective. A Markov model of a state-dependent service rate queue with rate transitions only at service completion is used to evaluate the performance of ALR with respect to mean packet delay, time spent in an energy-saving low data rate, and oscillation of link data rates. Simulation experiments using actual and synthetic traffic traces show that an Ethernet link with ALR can operate at a lower data rate for over 80% of the time yielding significant energy savings with only a very small increase in packet delay.

[1] L. Benini, A. Bogliolo, G. Paleologo, and G. De Micheli, “Policy Optimization for Dynamic Power Management,” IEEE Trans. Computer-Aided Design of Integrated Circuits and Systems, vol. 18, no. 6, pp. 813-833, June 1999.
[2] “Broadcom BCM5701 10/100/1000BASE-T Controller Product Brief,” pdf , 2005.
[3] “Carbon Dioxide Emissions from the Generation of Electric Power in the United States,” US Dept. of Energy and the Environmental Protection Agency, page/co2_reportco2report.html, July 2000.
[4] E. Chong and W. Zhao, “Performance Evaluation of Scheduling Algorithms for Imprecise Computer Systems,” J. Systems and Software, vol. 15, no. 3, pp. 261-277, July 1991.
[5] K. Christensen, C. Gunaratne, B. Nordman, and A. George, “The Next Frontier for Communications Networks: Power Management,” Computer Comm., vol. 27, no. 18, pp. 1758-1770, Dec. 2004.
[6] E.-Y. Chung, L. Benini, A. Bogliolo, Y.-H. Lu, and G. De Micheli, “Dynamic Power Management for Nonstationary Service Requests,” IEEE Trans. Computers, vol. 51, no. 11, pp. 1345-1361, Nov. 2002.
[7] M. Crovella, M. Harchol-Balter, and C. Murta, “Task Assignment in a Distributed System: Improving Performance by Unbalancing Load,” ACM SIGMETRICS Performance Evaluation Rev., vol. 26, no. 1, pp. 268-269, June 1998.
[8] “EU Stand-by Initiative, Minutes of the Third Meeting on Energy Consumption of Broadband Communication Equipment and Networks,” European Commission DG JRC, Ispra, standby_initiative.htm, Nov. 2005.
[9] A. Field, U. Harder, and P. Harrison, “Network Traffic Behaviour in Switched Ethernet Systems,” Performance Evaluation, vol. 58, no. 2, pp. 243-260, 2004.
[10] R. Gebhard, “A Queueing Process with Bilevel Hysteretic Service-Rate Control,” Naval Research Logistics Quarterly, vol. 14, pp. 55-68, 1967.
[11] G. Ginis, “Low Power Modes for ADSL2 and ADSL2+,” SPAA021, Broadband Comm. Group, Texas Instruments, Jan. 2005.
[12] S. Gochman et al., “The Intel Pentium M Processor: Microarchitecture and Performance,” Intel Technology J., vol. 7, no. 2, pp. 21-36, May 2003.
[13] R. Golding, P. Bosch, and J. Wilkes, “Idleness Is Not Sloth,” Technical Report HPL-96-140, Hewlett-Packard Laboratories, Oct. 1996.
[14] D. Gross and C. Harris, Fundamentals of Queueing Theory, third ed. John Wiley & Sons, 1998.
[15] C. Gunaratne and K. Christensen, “Ethernet Adaptive Link Rate: System Design and Performance Evaluation,” Proc. 31st IEEE Conf. Local Computer Networks, pp. 28-35, Nov. 2006.
[16] C. Gunaratne, K. Christensen, and B. Nordman, “Managing Energy Consumption Costs in Desktop PCs and LAN Switches with Proxying, Split TCP Connections, and Scaling of Link Speed,” Int'l J. Network Management, vol. 15, no. 5, pp. 297-310, Sept./Oct. 2005.
[17] C. Gunaratne, K. Christensen, and S. Suen, “Ethernet Adaptive Link Rate (ALR): Analysis of a Buffer Threshold,” Proc. IEEE Global Telecomm. Conf., Nov. 2006.
[18] M. Gupta and S. Singh, “Greening of the Internet,” Proc. ACM SIGCOMM '03, pp. 19-26, Aug. 2003.
[19] M. Gupta, S. Grover, and S. Singh, “A Feasibility Study for Power Management in LAN Switches,” Proc. 12th IEEE Int'l Conf. Network Protocols, pp. 361-371, Oct. 2004.
[20] IEEE 802.3 Energy Efficient Ethernet Study Group, index.html, 2006.
[21] IEEE 802.3 LAN/MAN CSMA/CD Access Method, , 2006.
[22] ITU Recommendation G.992.3: Asymmetric Digital Subscriber Line Transceivers 2 (ADSL2), 992.3en, 2006.
[23] ITU Recommendation G.992.5: Asymmetric Digital Subscriber Line (ADSL) Transceivers, 992.5en, 2006.
[24] ITU Recommendation G.993.1: Very High Speed Digital Subscriber Line Transceivers, 993.1en, 2006.
[25] V. Kulkarni, Modeling, Analysis, Design, and Control of Stochastic Systems, Springer, 1999.
[26] B. Nordman and K. Christensen, “Reducing the Energy Consumption of Network Devices,” Tutorial presented at the July 2005 IEEE 802 LAN/MAN Standards Committee Plenary Session, pubs.html, July 2005.
[27] B. Nordman and A. Meier, “Energy Consumption of Home Information Technology,” Technical Report LBNL-53500, Energy Analysis Dept., Lawrence Berkeley Nat'l Laboratory, July 2004.
[28] A. Odlyzko, “Data Networks Are Lightly Utilized, and Will Stay That Way,” Rev. Network Economics, vol. 2, no. 3, pp. 210-237, Sept. 2003.
[29] Z. Ren, B. Krogh, and R. Marculescu, “Hierarchical Adaptive Dynamic Power Management,” IEEE Trans. Computers, vol. 54, no. 4, pp. 409-420, Apr. 2005.
[30] J. Roberson, C. Webber, M. McWhinney, R. Brown, M. Pinckard, and J. Busch, “After-Hours Power Status of Office Equipment and Inventory of Miscellaneous Plug-Load Equipment,” Technical Report LBNL-53729, Energy Analysis Dept., Lawrence Berkeley Nat'l Laboratory, Jan. 2004.
[31] K. Roth, F. Goldstein, and J. Kleinman, Energy Consumption by Office and Telecommunications Equipment in Commercial Buildings, Volume I: Energy Consumption Baseline. Arthur D. Little Reference No. 72895-00, Jan. 2002.
[32] K. Roth, R. Ponoum, and F. Goldstein, U.S. Residential Information Technology Energy Consumption in 2005 and 2010. TIAX Reference No. D0295, Mar. 2006.
[33] H. Schwetman, “CSIM19: A Powerful Tool for Building System Models,” Proc. 33rd Winter Simulation Conf., pp. 250-255, Dec. 2001.
[34] M.B. Srivastava, A.P. Chandrakasan, and R.W. Brodersen, “Predictive System Shutdown and Other Architectural Techniques for Energy Efficient Programmable Computation,” IEEE Trans. Very Large Scale Integration (VLSI) Systems, vol. 4, no. 1, pp. 42-55, Mar. 1996.
[35] United States Energy Information Administration, Electric Power Monthly, Table 5.3, epmepm_sum.html, June 2007.
[36] “US EPA Energy Star Program Requirements for Computers: Version 4.0,” http://www.energystar.govindex.cfm?c=revisions. computer_spec , 2006.
[37] C. Webber, J. Roberson, R. Brown, C. Payne, B. Nordman, and J. Koomey, “Field Surveys of Office Equipment Operation Patterns,” Technical Report LBNL-46930, Energy Analysis Dept., Lawrence Berkeley Nat'l Laboratory, Sept. 2001.
[38] K. Yoshigoe and K. Christensen, “A Parallel-Polled Virtual Output Queued Switch with a Buffered Crossbar,” Proc. IEEE Workshop High Performance Switching and Routing, pp. 271-275, May 2001.

Index Terms:
Power management, energy-aware systems, local-area networks, Ethernet, Energy Efficient Ethernet
Chamara Gunaratne, Kenneth Christensen, Bruce Nordman, Stephen Suen, "Reducing the Energy Consumption of Ethernet with Adaptive Link Rate (ALR)," IEEE Transactions on Computers, vol. 57, no. 4, pp. 448-461, April 2008, doi:10.1109/TC.2007.70836
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