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© Technical University of Catalonia - Second University of Naples - University of Naples Federico II 1

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, Spain2Second University of Naples

3University of Naples Federico II

HANDBOOK ON GREEN INFORMATION AND COMMUNICATION SYSTEMS


Table of contentsTable of contents

IntroductionBackground & MotivationsNetwork energy consumptionEnergy-aware architecturesEnergy modelsMultilevel approachEnergy Efficiency & Energy AwarenessEnergy Oriented Architectures


Network energy consumptionNetwork 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’sLaw

Moore’s Law


Network energy consumptionNetwork 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]


Network energy consumptionNetwork energy consumptionEvolution of the bandwidth capacity and energy-per-bit consumption

Period windows: 10 yearsBandwidth increment: x1000

Energy per bit: ÷ 100Energy 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]

Source: [24]


Energy consumption: access vs backbone

Backbone energy

Consumption

2009:< 10%

Backbone energy

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]


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 sourcesAlternate 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 vapor 36–72%

carbon dioxide CO2 9–26%

methane 4–9%

ozone 3–7%

nitrous oxide ~1%

chlorofluorocarbons ~1%

Global Warming Potential (GWP)CO2 equivalent (CO2e)


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

Renewable energies


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.


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)


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)


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!!!


Energy-aware architecturesCurrent router architectures are not energy-aware

Source: [25]

UDP traffic with different packet

sizes

UDP traffic with medium packet size

with different features enabled

average offered load of

75%

The difference between idle and heavily loaded router vary only of 3% (about 25 W on 750 W)…

Energy consumption is a function of capacity, not throughputEnergy consumption is a function of capacity, not throughput


Energy-aware architecturesEnergy-aware architectures

…power consumption of base system is 50% of full line cards configuration

Source: [25]

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])

…but…


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]


Optical vs Electronic devices

Total power consumption vs the aggregated bandwidth for electronic and optical router technologies

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.

Source: [24]


3R Regeneration,Optical amplifiers 3R Regeneration,Optical amplifiers & dispersion compensation& 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]


Router power consumption:

Fixed part due for the device to stay on

Variable part somehow proportional to the traffic load

Energy-aware architecturesEnergy-aware architectures

Power (P)kWatt

Router aggregated bandwidthLoad (L)

Tbps

Fixed power consumption due to the

base system

Total power consumption

Variable power consumption

Idle


Sleep modeSleep 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


ALR & LPI hybrid conceptALR & 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)


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 microseconds Ts = ~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]


A Multi-layer approachA Multi-layer approach 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)


Energy-oriented network Energy-oriented network infrastructureinfrastructure

Source: [47]


Green network control plane


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 architecturesEnergy-efficient architectures Energy-aware algorithms & protocolsEnergy-aware algorithms & protocols Energy-oriented infrastructures (Energy-oriented infrastructures (sustainable systemic approach + LCA)sustainable systemic approach + LCA)


References1. Gartner press release, http://www.gartner.com/it/page.jsp?id=503867, 2007.

2. An inefficient Truth by the Global Action Plan, http://www.globalactionplan.org.uk/upload/resource/Full-report.pdf.

3. SMART 2020: Enabling the low carbon economy in the information age, The climate group, 2008.

4. EU Spring Summit, Brussels, Mar. 2007.

5. Global Action Plan Report, An inefficient truth, http://www.globalactionplan.org.uk/, 2007

6. C. Lange, “Energy-related Aspects in Backbone Networks”, in Proc. ECOC 2009, Vienna, Austria, Sep. 2009.

7. S.Pileri, “Energy and Communication: engine of the human progress”, INTELEC 2007 keynote, Rome, Italy, Sep. 2007.

8. 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.

9. BT Press, “BT announces major wind power plans”, Oct. 2007, http://www.btplc.com/News/Articles/Showarticle.cfm?ArticleID=dd615e9c-71ad-4daa-951a-55651baae5bb.

10. Telefónica supplement, The environment and climate change, 2008 special report on corporate responsibility, Apr. 2009.

11. H.D. Saunders, “The Khazzoom-Brookes postulate and neoclassical growth”, The Energy Journal, Oct. 1992.

12. C. Lange, D. Kosiankowski, C. Gerlach, F. Westphal, A. Gladisch, “Energy Consumption of Telecommunication Networks”, in Proc. ECOC 2009, Vienna, Austria, Sep. 2009.

13. Nature Photonics technology conference 2007, Tokyo, Japan, Oct. 2007.

14. M. Gupta, S. Singh, “Greening of the Internet”, in Proc. ACM SIGCOMM 2003, Karlsruhe, Germany, Aug. 2003.

15. 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.

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17. 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.


References18. L. Chiaraviglio, M. Mellia, F. Neri, “Energy-aware Backbone Networks: a Case Study”, GreenComm – First International

Workshop on Green Communications, Dresden, Germany, Jun. 2009.

19. 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.

20. 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 .

21. 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.

22. Juniper, http://www.juniper.net.

23. 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.

24. 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.

25. 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.

26. 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.

27. I. Cerutti, M. Tacca, A. Fumagalli, “The multi-hop multi-rate wavelength division multiplexing ring”, IEEE/OSA Journal of Lightwave Technologies, vol. 18, 2000.

28. Energy Star, “Small network equipment”, http://www.energystar.gov/index.cfm?c=new_specs.small_network_equip.

29. Gordon E. Moore, “Cramming more components onto integrated circuits”, Electronics, Volume 38, Number 8, April 19, 1965.

30. George F. Gilder, “Telecosm: How Infinite Bandwidth Will Revolutionize Our World”, The Free Press, NY, 2000.


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