Chapter 18: Towards Energy-Oriented Telecommunication Networks

1. HANDBOOK ON GREEN INFORMATION AND COMMUNICATION SYSTEMS Chapter 18: Towards Energy-Oriented Telecommunication Networks 1Sergio Ricciardi, 2Francesco Palmieri, 3Ugo Fiore, 1Davide Careglio, 1Germán Santos-Boada, 1Josep Solé-Pareta 1Technical University of Catalonia, Spain 2Second University of Naples 3University of Naples Federico II

2. Table of contents • Introduction • Background & Motivations • Network energy consumption • Energy-aware architectures • Energy models • Multilevel approach • Energy Efficiency & Energy Awareness • Energy Oriented Architectures

3. Network energy consumption • In Italy, Telecom Italia, and in France, France Telecom, are the second largest consumers of electricity after the National Railway systems: 2 TWh per year. • In the UK, British Telecom is the largest single power consumer. [7][8]

4. The Growing Dynamics • CPU computing power doubles every 18 months(Gordon Moore, 1964) • The available network bandwidth doubles every 6 months (George Gilder, 1992) Gilder’s Law Moore’s Law

5. Network energy consumption • Moore’s and Gilder’s laws [2][3] have not had the expected counterpart in power consumption reduction (Jevons paradox [4]) • As a consequence, the total power required per node is growing faster and faster. Network infrastructures consume: • 22 GW  1,16% worldwide produced electrical energy • Growth rate: 12% per year[24]

6. Network energy consumption Evolution of the bandwidth capacity and energy-per-bit consumption Source: [24] Period windows: 10 years Bandwidth increment: x1000 Energy per bit: ÷ 100 Energy consumption increment: x10 more than 10 years ago Technological advancements foreseen by Moore’s law have not been fully compensated by the same growth in energy-efficiency [47]

7. Energy consumption: access vs backbone Backboneenergy Consumption 2009: < 10% Backboneenergy Consumption 2017: ~ 40% • Energy consumption currently dominated by the access network because of the high number of end-point devices [31] • ADSL link: 2.8 W, while using as the access infrastructure • GPON (gigabit-capable passive optical network): only 0.5 W (80% improvement) • With rising traffic volume, the major consumption is expected to shift from access to core networks [12]

8. Environmental impacts • Human’s activities have severe impacts on the environment • Energy-consumption, resource exploitation • GHG emissions, climate changes, global warming & dimming, pollution • Human ecological footprint • measures the humanity’s demand on the biosphere • 1,5 planet Earths in 2007 [48] • Carbon footprint • Measures the total set of GHG emissions • Three dimensions • Energy consumption (Wh) • GHG emissions (kg CO2) • Energy Cost (€)

9. Alternate energy sources • Green & dirty energy sources • Green: solar, wind, tide, geothermic • Dirty: fossil fueled (coal, oil, gas) and nuclear plants • Green sources are renewable • Use Green source as possible! • Major contributors to the GH effect: • water vapor36–72% • carbon dioxide CO29–26% • methane4–9% • ozone3–7% • nitrous oxide ~1% • chlorofluorocarbons~1% • Global Warming Potential (GWP) • CO2 equivalent (CO2e)

10. Renewable energies • Advantages: • Virtually endless (5.000 millions years) • Zero carbon (green): no GHG emissions nor pollution during the use phase • Free energy: zero costs in the use phase (except maintenance operations) • Renewable Energy Sources are beneficial over their entire Life-Cycle [34] • Drawbacks • Low yield (solar panels efficiency ~25% as maximum) • Not always available (e.g., day/night cycle) nor always foreseeable • Not always applicable as the only energy sources (e.g. mobility) • Allow paradigm shift from centralized to distributed energy system (Smart Grid) • Centralized system: 1 big power plant giving energy to the whole region • Distributed system: n small power plants providing energy for private use and putting surplus energy into the power grid • Follow-the-whatever paradigm • Energy form a cost to a revenue source

11. Towards energy-efficiency • Energy-Efficiency • refers to a technology designed to reduce the equipment energy consumption without affecting the performance, according to the do more for less paradigm. It takes into account the environmental impact of the used resources and constraints the computations to be executed taking into account the ecological and potentially the economic impact of the used resources. Such solutions are usually referred to as eco-friendly solutions.

12. Is energy efficiency sufficient? • The simplest approach is improving the efficiency of the individual devices involved • Energy efficiency alone is not sufficient to achieve effective results (the Jevons paradox occur)

13. The energy-oriented paradigm • Energy-Awareness • refers to an intelligent technology that adapts its behavior or performance based on the current working load and on the quantity and quality of energy that the equipment is expending (energy-feedback information). It implies knowledge of the (dirty or green) sources of energy that supply the equipment thus differentiating how it is currently being powered. Energy-aware solutions are usually referred to as eco-aware solutions. • Energy-Oriented Infrastructures • Energy-Efficiency + Energy-Awareness in a holistic,sustainable and systemic approach with smart grid power distribution network and entire life cycle assessment (LCA)

14. An energy oriented approach • Energy as an additional constraint to operate into network and data centers infrastructures • Current worldwide energy shortages • Rising costs of energy (as fossil sources become scarcer) • Green House effect, Global Warming and Pollution • Need for alternative and renewable energy sources • Growing interests of governments and society into eco-concerns • Lack of a comprehensive energy-oriented paradigm • Energy-efficient + energy-aware solutions in a systemic approach • Renewable energy sources • Energy models • The basic Principle • Do more for less!!!

15. Energy-awarearchitectures • Current router architectures are not energy-aware average offered load of 75% UDP traffic with different packet sizes Source: [25] The difference between idle and heavily loaded router vary only of 3% (about 25 W on 750 W)… UDP traffic with medium packet size with different features enabled Energy consumption is a function of capacity, not throughput

16. Energy-aware architectures …power consumption of base system is 50% of full line cards configuration …but… Power consumption for different installed line cards configurations of the GSR Cisco Router Power consumption for different installed line cards configurations of the 7507Cisco Router Focus on energy-aware architectures that can adapt their behavior, and so, their energy consumption, to the current traffic loads (advocated both by standardization bodies and governmental programs and assumed in many literature sources [25]) Source: [25]

17. Optical Networks are cheaper • Optical transport (WDM) consumes relatively little energy • Access network dominates at low rates • Eliminating the O/E/O converters is not the only solution • Network routers dominate at higher rates: • reduce hop count • improve router efficiency (technology) • manage routers better (sleep states) • develop better network architectures using fewer routers • manage distribution and replication of contents Number of Hops in the Internet[31]

18. Optical vs Electronic devices Total power consumption vs the aggregated bandwidth for electronic and optical router technologies Source: [24] Optical Cross-Connect node (OXC) with micro-electro-mechanical system (MEMS) switching logic consumes about 1.2 W per single 10 Gb/s capable interface, whereas a traditional IP router requires about 237 W per port.

19. 3R Regeneration,Optical amplifiers & dispersion compensation • 3R regeneration should be avoided as much as possible in planning, designing and managing new paths throughout an optical infrastructure (60 W per channel) use optical amplifiers, try to avoid 3R as much as possible • EDFA are more performing (higher gain, lower insertion loss, noise and cross-talk effects) than SOA but have also higher energy consumption (respectively 25 W and 3 W)[24] • Use dispersion compensation fibers (DSF ITU-T G.653, NZ-DSF ITU-T G.655/656) instead of “simple”single mode fiber (SMF, ITU-T G.652) will reduce the dispersion of the optical signal traversing the fiber and reduce the number of required optical amplifiers [47]

20. Energy-aware architectures • Router power consumption: • Fixed part due for the device to stay on • Variable part somehowproportional to the traffic load Power (P) kWatt Total power consumption Variable power consumption  Fixed powerconsumption due to the base system Load (L) Tbps Router aggregated bandwidth Idle

21. Sleep mode • Putting entire network nodes down when they are not used • Generic problems • Load balancing • Time consuming • Start-up & configuration problem + peak in power usage • Lifetime (MTBF) • Economic CAPEX & OPEX • Per-interface sleep mode / Adaptive rate / Low Power Idle[39] / STOP-START Energy proportional computing / Downclocking

22. ALR & LPI hybrid concept • Idea: temporarily switching off or downclocking unloaded interfaces and line cards (per interface sleep mode) to save energy • Adaptive Link Rate (ALR) and Low Power Idle (LPI)

23. ALR & LPI • ALR: Native and working link rate • dynamically modify the link rate according to the real traffic needs • LPI: transmission on single interface is stopped when there is no data to send and quickly resumed when new packets arrive • in contrast with the continuous IDLE signal used in legacy systems • few microsecondsTs = ~2 s , Tw = ~ 4 s (@10Gbps) • Power consumption in LPI: ~10% of active mode • Power consumption in transition ~50%-100% of active mode • Depends on the packet arrival distribution -> buffering, packet coalescing and coordinated Ethernet [6][12][13]

24. A Multi-layerapproach • Network Administration Procedures • Are aware of the power state of the nodes and the currently set power policy • Network Engeneering and Management • Load balancing, scheduling & task distribution • Shut down idle nodes • Networking Protocols • Energy-efficiency, energy-awareness, energy-oriented paradigm • Decrease overall usage of network • Optimized placement/replication of data to minimize equipment usage • Minimize time to transfer data & reduce data to be transmitted (forecasting techniques)

25. Energy-oriented network infrastructure Source: [47]

26. Green network control plane

27. Conclusions • Energy as a new constraint – considering the current energy consumption growth rate – even stronger than the bandwidth capacity • Energy-aware architectures are necessary to minimize the energy consumption • Assess the power consumption of ICT and network infrastructures • In general: • Energy-efficient architectures • Energy-aware algorithms & protocols • Energy-oriented infrastructures (sustainable systemic approach + LCA)

28. References • Gartner press release, http://www.gartner.com/it/page.jsp?id=503867, 2007. • An inefficient Truth by the Global Action Plan, http://www.globalactionplan.org.uk/upload/resource/Full-report.pdf. • SMART 2020: Enabling the low carbon economy in the information age, The climate group, 2008. • EU Spring Summit, Brussels, Mar. 2007. • Global Action Plan Report, An inefficient truth, http://www.globalactionplan.org.uk/, 2007 • C. Lange, “Energy-related Aspects in Backbone Networks”, in Proc. ECOC 2009, Vienna, Austria, Sep. 2009. • S.Pileri, “Energy and Communication: engine of the human progress”, INTELEC 2007 keynote, Rome, Italy, Sep. 2007. • L. Souchon Foll, “TIC et Énergétique: Techniques d'estimation de consommation sur la hauteur, la structure et l'évolution de l'impact des TIC en France”, Ph.D. dissertation, Orange Labs/Institut National des Télécommunications, 2009. • BT Press, “BT announces major wind power plans”, Oct. 2007, http://www.btplc.com/News/Articles/Showarticle.cfm?ArticleID=dd615e9c-71ad-4daa-951a-55651baae5bb. • Telefónica supplement, The environment and climate change, 2008 special report on corporate responsibility, Apr. 2009. • H.D. Saunders, “The Khazzoom-Brookes postulate and neoclassical growth”, The Energy Journal, Oct. 1992. • C. Lange, D. Kosiankowski, C. Gerlach, F. Westphal, A. Gladisch, “Energy Consumption of Telecommunication Networks”, in Proc. ECOC 2009, Vienna, Austria, Sep. 2009. • Nature Photonics technology conference 2007, Tokyo, Japan, Oct. 2007. • M. Gupta, S. Singh, “Greening of the Internet”, in Proc. ACM SIGCOMM 2003, Karlsruhe, Germany, Aug. 2003. • R.S. Tucker et al., “Evolution of WDM Optical IP Networks: A Cost and Energy Perspective”, IEEE/OSA Journal of Lightwave Technologies, vol. 27, no. 3, pp. 243-252, Feb. 2009. • B. St Arnaud, “ICT and Global Warming: Opportunities for Innovation and Economic Growth”, http://docs.google.com/Doc?id=dgbgjrct\2767dxpbdvcf. • A. Muhammad, Paolo Monti, Isabella Cerutti, Lena Wosinska, Piero Castoldi, Anna Tzanakaki, “Energy-Efficient WDM Network Planning with Protection Resources in Sleep Mode”, accepted for Globecom 2010, ONS01.

29. References • L. Chiaraviglio, M. Mellia, F. Neri, “Energy-aware Backbone Networks: a Case Study”, GreenComm – First International Workshop on Green Communications, Dresden, Germany, Jun. 2009. • W. Van Heddeghem, M. De Groote, W. Vereecken, D. Colle, M. Pickavet, P. Demeester, “Energy-Efficiency in Telecommunications Networks: Link-by-Link versus End-to-End Grooming”, in Proc. of ONDM 2010, Feb. 1-3 2010, Kyoto, Japan. • R. S. Tucker, “Modelling Energy Consumption in IP Networks”, retrieved from: http://www.cisco.com/web/about/ac50/ac207/crc_new/events/assets/cgrs_energy_consumption_ip.pdf. • W. Vereecken, W. Van Heddeghem, D. Colle, M. Pickavet, P. Demeester, “Overall ICT footprint and green communication technologies”, in Proc. of ISCCSP 2010, Limassol, Cyprus, Mar. 2010. • Juniper, http://www.juniper.net. • M. Z. Feng, K. Hilton, R. Ayre, R. Tucker, “Reducing NGN Energy Consumption with IP/SDH/WDM”, in Proc. 1st International Conference on Energy-Efficient Computing and Networking, Passau, Germany, pp: 187-190, 2010, ISBN:978-1-4503-0042-1. • BONE project, 2009, “WP 21 Topical Project Green Optical Networks: Report on year 1 and updated plan for activities”, NoE, FP7-ICT-2007-1 216863 BONE project, Dec. 2009. • J. Chabarek, J. Sommers, P. Barford, C. Estan, D. Tsiang, and S. Wright, “Power awareness in network design and routing”, in Proc. IEEE INFOCOM, 2008. • S. Aleksic, “Analysis of Power Consumption in Future High-Capacity Network Nodes”, Journal of Optical Communications and Networking, vol. 1, no. 3, pp. 245-258, Aug. 2009. • I. Cerutti, M. Tacca, A. Fumagalli, “The multi-hop multi-rate wavelength division multiplexing ring”, IEEE/OSA Journal of Lightwave Technologies, vol. 18, 2000. • Energy Star, “Small network equipment”, http://www.energystar.gov/index.cfm?c=new_specs.small_network_equip. • Gordon E. Moore, “Cramming more components onto integrated circuits”, Electronics, Volume 38, Number 8, April 19, 1965. • George F. Gilder, “Telecosm: How Infinite Bandwidth Will Revolutionize Our World”, The Free Press, NY, 2000.

30. Thanks for your attention!