Optical interconnects in data centers

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Optical interconnects in data centers

Optical Communication Systems and Networks:

From Data Centers to Broadband Access to Core

Transport Networks

9 May 2014

Christoforos Kachris

Athens Information Technology (AIT)

email: [email protected]

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How Big are Data Centers

Data Center Site

Sq ft

Facebook (Santa Clara)

86,000

Google (South Carolina)

200,000

HP (Atlanta)

200,000

IBM (Colorado)

300,000

Microsoft (Chicago)

700,000

C. Kachris, Athens Infromation Technology, May 2014

[Source: “How Clean is Your Cloud?”, Greenpeace 2011]

Wembley Stadium:172,000 square ft

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Data Center Traffic

• In 2014,

77%

of traffic remained within the data center,

and this will decline only slightly to 76 percent by 2015

(5)

Data Centers Power Consumption

• Data centers consumed

330 Billion KWh

in 2007 and is expected to

reach

1012 Billion KWh

in 2020

2007 (Billion KWh)

2020 (Billion KWh)

Data Centers

330 1012

Telecoms

293

951 Total Cloud

623 1963

[Source: How Clean is Your Data Center, Greenpeace, 2012

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Power consumption of Data

Centers

• The cost to power and cool

the data centers will reach

the CAPEX cost

• Data center networks

(DCN) consume as much as

23% of the total power

consumption

• Data center servers

consume as much as 40%

of the total power

consumption in a Data

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Data Center Networks

The Data Center Networks are

usually based on a fat-tree

topology using commodity

switches

Core Layer: Used to

interconnect the access

switches (10Gbps)

Aggregate Layer: Used to

interconnect the ToR switches

(10Gbps)

Rack Layer: Top-of-Rack (ToR)

switches are used to connects

the servers in a rack (1Gbps)

…

ToR switches Aggregate Switches 10 Gbps Rack Core switches Servers Internet

Rack Rack Rack 10 Gbps Data Center

Content switches & Load balance

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Data Center Networks

…

ToR switches Aggregate Switches 10 Gbps Rack Core switches Servers Internet

Rack Rack Rack 10 Gbps Data Center

Content switches & Load balance

SERENDIPITY

Telecommunication network follow a similar

approach:

Core network,

Aggregation/Metro Network,

Access network

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Opaque to transparent networks

[Source: C. Kachris, K. Kanonakis, I. Tomkos, Optical Interconnection Networks in Data Centers: recent trends

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Opaque to transparent networks

[Source: C. Kachris, K. Kanonakis, I. Tomkos, Optical Interconnection Networks in Data Centers: recent trends and future challenges, Communication Magazine, 2014]

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How green is all-optical?

• Current switches consume

a high amount of energy

for the

E/O

,

O/E

,

buffers

and

Switch Fabrics

C. Kachris, Athens Infromation Technology, May 2014 11

• All-optical switches

can

eliminate the need for

buffers, E/O and O/E

converters

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Need for All-optical Interconnects

• We need

High bandwidth

,

Low latency

,

scalable

,

energy efficient

Data Centers

Networks that can sustain the exponential

increase of the network traffic

• All-Optical Interconnects:

– No need for buffering

– Switching can be performed using passive

components at the

wavelength-level

(e.g. splitters,

wavelength switching - AWGR)

– Higher bandwidth (wavelength multiplexing)

– Lower latency

– Lower power consumption, footprint, carbon

emissions

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The optical “toolbox”

AWGR

Wavelength switching

WSS

Wavelength and spatial switching

Coupler

Optical MEMS

Spatial switching

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All-optical interconnects in AIT

• In the

WSS-based OFDM

scheme each node consists of a

rack that accommodates several servers and each rack uses

a Top-of-the-Rack (ToR) switch to communicate with other

racks.

• Each ToR switch has several optical transceivers (e.g. 1Gbps

SFP) to connect to the servers and one or more

optical

OFDM transceivers

Optical Switching Matrix

TRX λ1 λ2 λ3 … λ8 WSS Coupler MUX WSS-based Optical Switching WSS-based Optical Switching ToR λ1 λ2 λ3 … λ8 ToR λ1 λ2 λ3 … λ8 ToR OFD M TRX OF D M TRX OFD M TRX OF D M TRX OFD M TRX OF D M TRX OFD M TRX OF D M TRX OFD M TRX OFD M TRX OFD M TRX OFD M

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All-optical interconnects in AIT

• Power reduction

is achieved though the use of less

number of transceivers but enhanced with OFDM for

better spectral efficiency

Optical Switching Matrix

TRX λ1 λ2 λ3 … λ8 WSS Coupler MUX WSS-based Optical Switching WSS-based Optical Switching ToR λ1 λ2 λ3 … λ8 ToR λ1 λ2 λ3 … λ8 ToR OFD M TRX OF D M TRX OFD M TRX OF D M TRX OFD M TRX OF D M TRX OFD M TRX OF D M TRX OFD M TRX OFD M TRX OFD M TRX OFD M 15

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Potential Market

• All major internet service companies and

niche market that need low latency

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Market size of DCN

• The data center networking market currently stands at

$12.49 billion and will grow at a compound annual rate

of 11.8% during the next five year

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Start-ups in optical interconnects

Lightfleet ODM

solves the big data

dilemma for large

data centers

Compass-EOS is the first

commercially available

technology using optical

chip-to-chip

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Conclusions

• Future Data Center Network will require

high

bandwidth, low latency, energy-efficient

interconnects to face the traffic of cloud

computing

• Optical Interconnects looks as a promising

solution in providing

– high bandwidth

,

– low latency

and

– energy efficient interconnects

• Opportunity for

innovative all-optical

solutions/start-ups

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Questions?

• C. Kachris, I. Tomkos

A Survey on Optical Interconnects for Data Centers, IEEE Survey and Tutorials, 2012

• C. Kachris, K. Bergman, I. Tomkos,

“Optical Interconnects for Future Data Center Networks“,

Springer Publication, end of 2012

• Bibliography on optical interconnects for data centers

www.ait.gr/ait_web_site/Researcher/kachris/optical_interconnect_bibliography.htm