lecture: 7 energy efficiency in optical networks
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Lecture: 7 Energy Efficiency in Optical Networks. Ajmal Muhammad, Robert Forchheimer Information Coding Group ISY Department. Outline. Introduction to Energy Issue Network Device ’ s Power Profile Access, metro & core networks Approaches to low Energy Networking Energy Saving Strategies - PowerPoint PPT PresentationTRANSCRIPT
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Lecture: 7 Energy Efficiency in Optical Networks
Ajmal Muhammad, Robert ForchheimerInformation Coding Group
ISY Department
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Outline
Introduction to Energy Issue Network Device’s Power Profile
Access, metro & core networks Approaches to low Energy Networking Energy Saving Strategies Core, metro & access networks
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MotivationTwo main factors that drive the quest for “Green” networking(1) Reduction of CO2 emission
The ICT (Information and Communications Technology) sector is responsible for 2.0% of the global greenhouse emissions, estimated by ITU (International Telecommunication Union).
(2) Reduction of operational costPower consumption of the ICT (Information and Communications Technology) accounted for the 4% of the global energy consumption
BAU: Business-As-UsualECO: Eco Sustainable
For European Telecom network infrastructures
• 50 % of CO2 emission is due to the
production stage• 45% due to the usage stage• 5% due to recycling/disposal stage
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Terminal versus Network Power Consumption
Typical current mobile terminal power consumption is 0.83Wh per day (including battery charger and terminal).
The corresponding network power consumption is 120Wh.
The ratio is 150:1 and therefore the network power consumption is the main contributor to CO2 and effort has to be directed at the network primarily.
Significant research effort has gone into extending the mobile terminal battery life by optimizing and reducing its power utilization from 32Wh per day in 1990 to 0.83Wh per day in 2008, a factor of 38.
In comparison the network power consumption has received little attention to date.
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Power Consumption of Access Networks
Mobile access is becoming dominant access technology Any where, any time, any service
Mobile is least energy efficient~25 W/user @ 10 Mb/s
PON is most efficient~7 W/user
PON: Passive optical NetworkHFC: Hybrid fiber coaxialPtP: Point to pointFTTN: Fiber to the node or neighborhood
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Network Segmentation
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Key Components
• Customer home terminal ADSL modem, ONU….• Access network field equipment PON splitter, DSLAM, RF amps…• Central office equipment OLT, gateway, switch, base station,…
Access Network
Metro Network
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Key Components: Core Network• Core routers & switched• Number of router hops• Long haul & submarine optical WDM transport• EDFAs, Raman Amps, transmit & receive units, etc.• TDM and WDM cross connects & OADM
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Photonic Versus Electronic Switching
Photonic switching has much lower energy consumption compared to electronic switching.
It has been shown that the power needed per bit for switching is 100 to 1000 times higher in an electronic semiconductor switch as compared to a photonic switch.
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Data Centers and Content Servers
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Access, Metro, Core Power ConsumptionPON based access network - power consumption estimates are 10W for optical network units (ONU) and 100W for optical line terminal (OLT) which resides in an edge node.
Edge router in the metro, for example Cisco 12816, with capacity 160Gb/s consumes 4.21 kW. Efficiency= 26.5nJ/bit
Core router, such as Cisco CRS-1 with 640 Gb/s capacity consumes 1020 kW. Efficiency= 17nJ/bit
WDM systems connecting the edge nodes to the core node consume 1.5 kW for every 64 wavelengths.
Typically one multi-wavelength amplifier is required per fibre, consuming around 6W.
The WDM terminal systems connecting core nodes consume 811 W for every 176 channels, while each intermediate line amplifier consumes 622 W for every 176 channels.
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Router Power ConsumptionDominated by router forwarding engines
Power driver: IP look-up/forward engine
I/O- optical transport: is lower in powerConsumption than switch fabric
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Outline
Introduction to Energy Issue Network Devices Power Profiles
Access, metro, core network components
Approaches to Low Energy Networking Energy Saving Strategies Core, metro, access networks
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Approaches to low Energy Networking
1
2
3
Introduce and design: 1)More energy efficient elements for network devices2)Optimize the internal organization of devices3)Reduce devices intrinsic complexity levels
Modulate capacities of processing engines and of network interfaces, to meet actual traffic loads and requirements
Smartly and selectively drive unused network/device portions to low standby mode
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Network Domain Utilization
Internet traffic profile
Networks are provisioned withresources for worse case scenario
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Energy Saving in Core Networks
Approaches
Selectively turn down network elements
- Energy efficient protocols
Energy efficient network architectureEnergy efficient routing Green routing
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Energy Efficient Protocols
Sleep & standby states Network devices enter low power state when not in use
Can apply to systems and sub-systems Need to ensure network presence is retained use network connection proxy with sleep protocol
Need to account for state transition energy and time
May have multiple lower energy states
IEEE Energy Efficient Ethernet (802.3az) Low power idle mode when no packets are being sent Approved Sept. 2010 Currently applies to copper interface only; not optical
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Example: Exploiting Sleep Mode
must be active to support working lightpath
can be set to sleep
off: not used
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Dynamic Rate Adaptation
Modify capacity of network devices in response to traffic demands
Change clock frequency, processor voltage
Power = C x Voltage2 frequency
Slower speed to reduce power consumption
100 Mb/s uses 10-20 W less than 10GE, 4 W less than 1GE
Need to allow transition time between rates
Dynamic rate adaptation and standby states can be combined
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Sleep Mode for Dynamic NetworksSome nodes are selected to go to sleep according to the traffic flow and their location in the network topology
When nodes go to sleep, they can still transmit and receive traffic but they cannot route traffic
A node which is the only neighbour for another nodecannot go to sleep
Some traffic flows will have to take longer routes, i.e., energy is saved at the expense of QoS
If the network blocking probabilityexceeds the acceptable (service)blocking probability threshold, themost recent node to sleep wake up
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Energy Efficient Network Architecture
Architectures that reduce the number of router hops Optical bypass
Layer 2 rather than Layer 3 where possible
Without optical bypass:All traffic goes to IP layer for processing~10nJ per bitAllow aggregation of incoming traffic flowStatistical multiplexing
Layer 3
Layer 2
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Architecture: Bypass Option
With bypass:
TDM Layer Some traffic streams processed at TDM layer
~ 1nJ per bit
WDM Layer
Some traffic streams processed at WDM layer
< ~ 0.1nJ per bit
Switching wavelengths
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Energy Efficient RoutingNetwork with Dedicated Path Protection
Energy-unaware Routing Energy-aware Routing
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Energy Efficient RoutingNetwork with Shared Path Protection
Energy-unaware Routing Energy-aware Routing
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Green Routing
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Energy Saving in Metro Networks
Reduce Regeneration
PIC: Peripheral Interface Controller
WSS: Wavelength Selective Switch
ROADM: Reconfigurable Optical Add Drop Multiplexer
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Energy Efficient Traffic Grooming
DXC: Digital cross-connect
OXC: Optical cross-connect
FG: First Generation
SH: Single-hop
MH: Multi-hop
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Energy Efficiency in Access Networks Remove Layers
Network simplification
Today
IP
ATM
PSTN
DPCN
PDH
SDH - mesh
SDH - MSH
IP
ATM
PSTN
DPCN
PDH
SDH - mesh
SDH - MSH
DSL
KiloStream
PSTN
Fibre
Copper
DWSS
21CN
IP/MPLSFibre &Copper
Copper
MSAN
Call Control
Content
WWW
ISP
Multi - service access Converged core
Current thinking. No implementation assurances
Wireless
Ethernet Backhaul
Other CPs
I/connects
British Telecom network architecture today
More power
Less power
Future Plan
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From PON to Long Reach-PON
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The Ring-and-Spur LR-PON
Two dimensional coverage for failure protection
Reusing the existing metro rings
Cost-effective extended coverage integrated system less active sites low CapEx and OpEx
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