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Energy Consumption in IP Networks

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					         Energy Consumption in
              IP Networks
Rodney S. Tucker, Jayant Baliga, Robert Ayre, Kerry Hinton, Wayne V. Sorin

                    ARC Special Research Centre for
             Ultra-Broadband Information Networks (CUBIN)
                        University of Melbourne
                       r.tucker@ee.unimelb.edu.au
        Energy Consumption of the Network
                            Hot spot




Why should we be interested in energy?
                                                  Power In
 • OPEX
• Greenhouse Impact
• Managing “Hot Spots”
  - Getting the energy in
  - Getting the heat out
• Energy-limited capacity bottlenecks
• Enabling energy efficiencies in other sectors
    Where are We Heading ?

More users

More data-intensive applications, e.g. video

More often and for longer periods

Increasing demand → operators provide faster access
and increased core capacity

New applications enabled by faster access



  Energy Consumption Grows
                     Summary

Modeling energy consumption of the Internet
- Core, metro, and access networks

Where does the energy go?

Will (can) optical switching technologies help to reduce
energy consumption?

A Word of Warning
       What is the Carbon Footprint of Telecoms?
                     Global Telecoms Footprint (devices & infrastructure)

                               Mobile Network
 Fixed Narrowband                                           Mobile handsets



       2002

                               20X               1450+% growth
                               increase
      2020


                0                  100                  200            300         400
                                                                  Footprint (MtCO2 p.a.)
              Broadband                 Fixed Broadband
               Modems

Adapted from “SMART 2020: Enabling the low carbon economy
in the information age,” GeSI, 2008 www.gesi.org
                          Where does the Energy Go?
    CRS-1                                                                           Core
~ 10 kW / rack                      Core
                                                                                           Core
                                               Core         Core          Core
Packet                                                                              Core
 over
Sonet                          Fibre
                               Amps
                                                             WDM                           Metro
     12816 Edge                               Edge
       ~ 4 kW
                                                                             Edge



                       OLT - 100W          Curb                    Curb Curb     Curb
                                                                                           Access
                      OLT - 100W
 Passive
 Optical
 Network


                 ONU ~ 5-10W

                                            0.1 - 1000 Mb/s to the user
Baliga et al., 2007
                          Number of Hops in the Internet

                          2006 Data
                0.1


               0.08
Pr [ H = k ]




               0.06                                                         Multi ISP Network:
                                                                              15 - 20 hops

               0.04


               0.02


                 0
                      0         5         10        15                 20            25
                                         Number of Hops, k
Source: P. Van Mieghem,
“Performance Analysis of Computer Systems and Networks”, Cambridge (2006)
                               Power Consumption of IP Network
                      25
                                  20 router hops                 2007 Technology
                      20          Contention ratio = 25                                     1.0




                                                                                                  % of Electricity Supply
     Power (W/user)




                                                         Total
                      15
                               Today’s Internet
                                 (~ 2.5 Mb/s)
                                                           Routers
                      10                                                                    0.5
                                                                       Access (PON)
                       5
                                                             SDH/WDM Links

                       0                                                                    0
                           0           50          100           150       200        250
                                            Peak Access Rate (Mb/s)


Baliga et al., 2007
                                   Ultra-Broadband Access
                      100                                                                5.0
                                20 router hops               2007 Technology

                               Contention ratio = 25




                                                                                               % of Electricity Supply
     Power (W/user)




                                                               Total

                      50                                                                 2.5

                                                                        Routers

                                                 Access (PON)
                                                                       SDH/WDM

                       0                                                                 0
                           0                           500                        1000
                                           Peak Access Rate (Mb/s)


Baliga et al., 2007
  Energy Consumption in Access Networks
                                                       NEC CM7710T
            Access N/W             Cabinet

Edge Node                           Splitter                   PON

 Cisco
               NEC                  Cabinet            NEC VF200F6
 12816       CM7700S
                                                            FTTN with
                                                             VDSL2
                                           Zyxel
                                        VES-1616F-34
               Cisco                                   NEC GM100
               4503
                                                               PtP

                                                           Axxcelera
                                                           ExcelMax CPE


                           Axxcelera                         WiMAX
                         ExcelMax BTS
    Power Consumption in Access Networks
                         40
                                  Oversubscription = 10
                                                          25
    Power Per User (W)

                                     WiMAX

                                                                     FTTN
                         20
                                                                     PtP

                                                               PON

                          0
                              1                    10                100    250
                                           Peak Access Rate (Mb/s)

•            Wireless access consumes more energy than optical access
•            PON FTTH is “greener” than FTTN
                     Network Energy Consumption per Bit
                     10-3
                                         ~100 μJ/b                   20 hops
                     10-4
                                            ~1 μJ/b
Energy per bit (J)




                     10-5                                        Total


                     10-6
                               Routers
                                            Access (PON)
                     10-7
                                               WDM Links
                     10-8
                         2.5              25               250                 2500
                                         Peak Access Rate (Mb/s)
                           Observations
•   Optical transport (WDM) consumes relatively little energy
      < 5% of energy       > 25% of CAPEX

•   Eliminating the O/E/O converters provides no significant benefit

•   Access network dominates at low rates
    – Standby/Sleep mode is key to reducing energy consumption

•   Network routers dominate at higher rates
    – Need to
       • reduce hop count
       • improve router efficiency (technology)
       • manage routers better (sleep states)
       • develop better network architectures using fewer routers
       • manage distribution and replication of content (IPTV)
                                       Power Consumption in Routers
                   1,000,000
                                                                                         ?
                             100,000
                                                        P=   C2/3
                                                    where P is in Watts
     Power consumption (W)




                                                    where C is in Mb/s
                              10,000
                                                                                   10 nJ/bit
                              1,000
                                          P ~ 10
                                100
                                                             100 nJ/bit
                                 10

                                  1
                                       1 Mb/s       1 Gb/s                1 Tb/s               1 Pb/s
                                                   Router Throughput



Source: METI, 2006, Nordman, 2007
                  Energy Bottleneck
                 High-end router: Cisco CRS-1

Linecard Chassis          Switch Fabric Chassis:          Fully equipped:
Capacity: 0.64 Tb/s       Power: 8 kW                     Multi-rack router
Power: 13.6 kW                                            Capacity: 41 Tb/s
                                                          Power ~ 1 MW


                              X2 every
                             18 months



                                     Per Rack

                                 Source: Neilsen, 2006;
                                 Deutche Telekom, 2007
                        Electronic Routers
                          Forwarding Engine



Fibers


                                            J

                                   Switch
                                   Fabric

 Demutiplexers

                    O/E                                              Multiplexers
                                Switch Fabrics       Buffers
                 Converters
                       Reduced bit rate (i.e. parallel processing)
                        Speed (throughput) is not a limitation


                              Electronics        Optics
            Energy in Electronic and Optical Routers
 Line Card                                               Data Plane
                                  Buffer
                                                                          Routing
                           Forwarding Engine                Switch        Tables
         Amp      O/E                                                                      Power
                                                            Fabric
                                                                                          supply
         I/O                      Buffer                                                inefficiency
                                                            Switch       Routing
                                               Buffer       Control       Engine         Fans and
         Amp      O/E      Forwarding Engine
                                                                       Control Plane     blowers

                                                  Energy/bit                                    Total
 Electronic
                  0.7 nJ        3.2 nJ       0.5 nJ        1.0 nJ     1.1 nJ   3.5 nJ           10 nJ
  (2008)
 Electronic
  (2018)          10 pJ         65 pJ        10 pJ         20 pJ      25 pJ     80 pJ          210 pJ

  Optical
  (2018)          20 pJ         65 pJ        20 pJ ?       20 pJ      25 pJ     80 pJ          220 pJ


          Optical Packet Switching is not a compelling alternative
G. Epps, Cisco, 2007, ITRS, 2005, R. Tucker, JLT, 2006
Contention Resolution in the Wavelength Domain
            λ1                         Forwarding Engine

                                                                       Switch           • Optical Burst Switch
                                       Forwarding Engine               Fabric           • Optical Label Switch
           λn                          Forwarding Engine

Fatal Flaw: Require large n for low blocking probability (n ~3 -10 x)
                                                                                         Wong, JLT 2006
                        100                                                              Pathiban et al., JLT 2009
                                               Total
                              (Wavelength-domain contention resolution )
       Power (W/user)




                                                                                       Routers 1.2 X
                                      Total
                               (Conventional router)
                        50                                                             Routers


                                                                                       WDM 5 X

                                                                                       Access
                                                                                       WDM
                         00
                                                   500                          1000
                                           Peak Access Rate (Mb/s)
                                                        The Challenge
                                        10 % - 20 % p.a. continuous improvement in efficiency


                                   60                                                             3.0




                                                                                                        % of Electricity Consumption
                                                    Efficiency
        Total Power Per User (W)




                                            Improvement Rate = 0% p.a

                                   40                                      5% p.a                 2.0


                                                                                10% p.a
                                   20                                                             1.0


                                                                      Target
                                                                                      20% p.a
                                   0                                                              0
                                        1         100           200             300         400
                                                      Peak Access Rate (Mb/s)


Baliga, et al, 2008, unpublished
                               Summary

•   Energy consumption currently dominated by the access network

•   The energy bottleneck in routers is looming
    - More significant than the so-called “electronic speed bottleneck”

•   Key strategies for efficient network design
     -   Control energy in the access network (e.g. sleep mode in modems)
     -   Reduce the hop count (i.e. “agile” optical bypass)
     -   Energy-efficient network architectures
     -   Continuous improvement in (electronic) router efficiency
     -   Caching and content distribution networks
     -   O/E/O conversions not necessarily a problem

				
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