Are Optical Networks Green?Are Optical Networks Green?Rod Tucker

University of Melbourne

First Trans-Atlantic

MarconiTrans-Atlantic

FessendenTrans-Atlantic

NY -

Paris

Key West -

HavanaTAT-1

TAT-3

TAT-5 TAT-8

TAT-9

TAT-10TAT-11

TAT-12/13

Newhaven -

Azores

10-9

1860 1880 1900 1920 1940 1960 1980 2000 2020Year

Ener

gy/B

it/10

00-k

m (J

)

WirelessTelegraphyCoaxOptical + Regen.Optical + EDFA

10-6

10-3

103

106

1

~20% p.a. improvement

WDM terrestrial

204010-12

Historical Perspective Historical Perspective –– Transport SystemsTransport Systems

SummarySummary

Top-down estimate of energy consumption of the Internet-

Projections of current trends

-

Switches and routers-

Optical transport

-

Access network

Bottom-up estimate-

Based on theoretical and practical lower bounds

-

Transport energy-

Switching energy

-

Network energy

How to build an energy-efficient network

EthernetSwitch

OLTSplitter

Cabinet

Metro/Edge NetworkCore Network

Network Energy ModelNetwork Energy Model

Edge Routers FTTP

FiberCore Router

Video Distribution Network

Storage

ServerServer

Storage

Data Center

Fiber

Access Network

DSLDSLAM

Cu

OLT

ONU

Cabinet

FTTN

DSLAM

Cu

Broadband Network Gateways

Tier 1 Network

30

Peak Access Rate (Mb/s)

Pow

er P

er U

ser (

W)

1 10000

PON

100

20

10

10

M ~10

M = 1

Power Consumption in Access NetworksPower Consumption in Access Networks

M = 1

FTTP is “greenest”

WirelessM= 10

HFC

M= 10M= 1

M= Oversubscription

Point to Point Optical

M = 1

Fiber to the Node

2010 Technology

Energy per Bit in Network DevicesEnergy per Bit in Network DevicesE

nerg

y pe

r bit

(nJ)

0.01

0.1

1

10

100

1000

MEMSOXC

OpticalAmp

PICTx/Rx

DiscreteTx/Rx

PoSTx/Rx

EthernetSwitch

CoreRouter

PONONU

(10 Mb/s)

IPTVServer

Sub-wavelengthWavelength

20102010

Estim

atedSet-top Box:

1000 nJ/bHD IPTV:

10,000 nJ/b

Energy Efficiency Improvements with TimeEnergy Efficiency Improvements with Time

TAT-1TAT-3

TAT-5 TAT-8

TAT-9

TAT-10TAT-11

TAT-12/13

10-9

1920 1940 1960 1980 2000 2020YearTr

ansp

ort E

nerg

y/B

it/10

00-k

m (J

)

10-6

10-3

WDM terrestrial

204010-12

20 % p.a.

20% p.a. efficiency improvement in routers (Neilson, JSTQE, 2006)

13% p.a. efficiency improvement in routers (Tamm, BLTJ, 2010)

15% p.a. efficiency improvements in transport

(Han, IEEE Comms. Mag. 2010)

?

Peak Access Rate (Mb/s)

Routers and switches

Ener

gy p

er b

it (μ

J)

1.0

100

0.1

10

Total using 2010 Technology

2.5 10 100 250

Transport

Total (20% p.a. improvements)PON

2010 2020

0.01

20 hops

Network Energy Per BitNetwork Energy Per Bit

40% Access Rate Growth

Peak Access Rate (Mb/s)

Glo

bal N

etw

ork

Pow

er C

onsu

mpt

ion

(W)

2010 2020

Global Network Energy ConsumptionGlobal Network Energy Consumption

1.2 Billion Users

2.5 10 100 250107

40% Access Rate Growth

20% p.a. efficiency

improvement

10% Growth in user numbers

Routers and switches

108

1010

109

Transport

PON

107

1011

Total

1012 0% p.a. efficiency

improvement

2010 Global electricity supply

Lower Bounds on Network Energy ConsumptionLower Bounds on Network Energy Consumption

Top-down estimate of energy consumption of the Internet-

Projections of current trends

-

Switches and routers-

Optical transport

-

Access network

Bottom-up estimate-

Theoretical and practical lower bounds on energy

-

Transport energy-

Switching energy

-

Network energy

How can we build a more energy-efficient network

Stage 1

gα

Stage m

TX RXgα

PTX PRXPA PA

Lstage

Lower Bound on Optical Transport EnergyLower Bound on Optical Transport Energy

2 stageLbitA

AMP minr r

SNR m e hPEB B

α ν− = ∑

/TX min RX min

TX RX minr

P PEB

− −−

+= Dominates

Amplifier Energy

TX/RX Energy

Bit Rate

Data In

Modulator

Zmod

Vmod

Driver

PCW P1

MUX

PMUX

Imod

Pdriver

Cmod

50 Ω

Zmod

laserI

laserV

Optical TransmittersOptical Transmitters

= or

Lumped modulator

Distributed modulator

212 mod modE C V=

2

50mod

r

VEB

=

125mod

r

CB

< 50Ω(Tom Koch)

Minimum Amplifier Energy per BitMinimum Amplifier Energy per BitM

inim

um A

mpl

ifier

Ene

rgy,

EA

MP

-min

(pJ/

bit)

TX/RX ( ~2020)

Amplifiers (Theoretical

Lower Bound)

Amplifier Spacing, Lstage (km)

0

0.4

0 20 40 60 80 100 120 140 160

0.2

0.6

OOK

DBPSKShannon bound for SE =

1 b/s/Hz

0.8

1.0

Energy per Bit per 1000Energy per Bit per 1000--kmkm

TAT-1TAT-3

TAT-5 TAT-8

TAT-9

TAT-10TAT-11

TAT-12/13

10-9

1920 1940 1960 1980 2000 2020

Year

Ener

gy/B

it/10

00-k

m (J

)

10-6

10-3

WDM terrestrial

2040

10-12 Minimum TX/RX/amplifier energy ~ x 103

Acc

ess

Net

wor

k

Acc

ess

Net

wor

k

Switch

Switch

Switch

Switch Switch

Switch

Transport Transport

Use

r Por

tsStage 1 Stage s

NetworksNetworks

Clos

O/E

Optical Switch

Optical Inputs

O/E

O/E

E/O

E/O

E/O

Optical Switch

O/E/O

O/E/O

O/E/O

O/E/O

O/E/O

O/E/O

Optical Outputs

Optical Switch

Electronic Switch

Optical SwitchesOptical Switches

Optical Demultiplexing

Electronic Demultiplexing

O/E

O/E

O/E

O/EOptical Switch

Electronic DEMUX

Advanced Modulation

Formats

TDM

DQPSK, OFDM, etc.

Transport 1 –

1000 Gb/sSwitching and

Processing 0.1 –

10 Gb/s

Electronic Switch

Electronic Switch

Electronic Switch (a)

(b)

(c)

O/E InterfacesO/E Interfaces

Optical Switch TechnologiesOptical Switch Technologies

Electro-optic (O-E)

SOA gate arrays

AWG-based wavelength-routed switches

CMOS

Packet SwitchingPacket Switching

EcontrolEAMP

Optical Switch Array

τb

τp

Inputs Outputs

controlbit AMP

b

EE EN

= +

p

b

ττ

~ 104

for IP packets

Switch Energies per BitSwitch Energies per Bit

O/E Converters MUX/DEMUX

Peak Access Rate (Mb/s)

Routers and Switches

Net

wor

k En

ergy

per

bit

(J)

2.5 10 100 250

Transport

2010 2020

10-6

10-9

10-10

10-8

10-11

10-7

10-5

1000

X

XX

X

Switches

Transport

10-12

Equipment Data Current Trends (Moore’s Law)

Lower Bound “Limits”

~ x 104

difference

1

Global NetworkGlobal Network

Management and control,

interconnects, power supplies,

etc.Subsystem

Loss/Efficiencies and Energy OverheadsLoss/Efficiencies and Energy Overheads

ETotal

Key Function

Overheads

Eoverheads

Loss, Inefficiencies

Emin

minfunction

function

EE =η

Key Conclusion:

Minimizing Emin is not necessarily the best strategy for minimizing ETotal

Laser efficiency, system penalties, system margins,

etc

2 410 10min

Total

EE

− −= −

Power Consumption in Electronic RoutersPower Consumption in Electronic Routers

Route processors, 8%

Switch fabric, 15%

Buffers, 5%

Control plane, 12%

Forwarding plane, 25%

Security, 25%

Source: G. Epps, Cisco

I/O, 11%

Potentially Optical,

20%Electronics

•

Focus on the access network and Customer Premises Equipment–

Fiber to the Premises, sleep modes–

set-top boxes, IP-enabled HDTV’s, etc.

•

Reduce energy losses and overheads –

E.g., high-efficiency modulator drivers, EDFA pumps, ancillary circuitry–

All-optical transmission and switching may be of little help

•

Reduce number of network hops–

OADM’s, Layer 2 versus Layer 3, dedicated IPTV distribution

•

Operate network at high utilization–

QoS

issues, traffic engineering, sleep modes in the core

How to Build an EnergyHow to Build an Energy--Efficient NetworkEfficient Network

Data by Mail vs. Data by the InternetData by Mail vs. Data by the Internet

108

32-GB USB drives

Data by Mail:

Melbourne San Diego

The Internet

5x106

Kg CO2

Data by Internet:

3x109

GB

1000 Gb/s for 3x107

seconds

2x107

Kg CO2

Cargo Jet

(1 year)

(~24 hours)

•

Global consortium, launched January 12

•

Goal: x103

improvement in energy efficient of the network by 2020

•

Members:-

Bell Labs,Telifonica, Huawei, AT&T, China Mobile, Freescale

Semiconductor, Swisscom, Portugal Telecom, SAIT, INRIA, IMEC-

University of Melbourne (IBES), MIT, Stanford

-

More to follow

•

Outcomes:-

Reductions in carbon footprint and operating cost

-

Collaboration between leading experts from around the world

-

Opportunities to bring innovative new ideas and products to market

(www.greentouch.org)