Why Cable Bends

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Why Cable Bends Matter inEnterprise Networks and Why

Multimode Fiber PrevailsSharon Bois

Corning Optical Fiber

May 22 2010



Agenda• Multimode fiber remains the most cost-effective

choice for enterprise networks – Multimode primer (classification and bandwidth)

– Benefits of multimode fiber (versus single-mode fiber

and copper)

• Next generation multimode fibers and standards

– OM4 and next generation speeds (16 Gb/s, 40 Gb/s

and 100 Gb/s)

– Bend-insensitive multimode fiber



Multimode fiber types classifiedbased on bandwidth values

300 m1500/500200050OM3

50

50

62.5

Core Diameter

(µm)

550 m3500/5004700OM4

82 m500/500-OM2

33 m200/500-OM1

10G Link

Length

OFL 850/1300

(MHz.km)

EMB

(MHz.km)

“OM”

Designation

• Optical Multimode (OM) designations are per ISO/IEC

11801

• EMB = Effective Modal Bandwidth (Laser BW)

• OFL = Overfilled Bandwidth (Legacy/LED BW)



Lasers require new bandwidthmeasurement systems

OFL (Overfil led Launch)

• Designed to predict performance of low-speed LEDs, not lasers

• Power distributed over 100% of the fibercore, like LEDs

• Perturbations in index profile undetected

EMB (Effective Modal Bandwidth)

• DMD (Differential Mode Delay) basedmeasurement

• minEMBc or DMD-mask

• Power distributed in a narrow region

• Simulates an actual laser launch

• More accurate indication of performance inhigh-speed laser-based systems

Light Sources

(Typically 10 and 100 Mb/s)

(1, 2, 4, 8, 10 Gb/s and higher)



Tdelay

Fiber Core

Laser

Laser

Laser

Fiber Core

≈5µm

Laser

TSlow

TFast

1 of 2 DMD-based standards compliant measurementsOne laser type scanned across core

BW defined by most delayed pulse

Laser

6 Masks Applied for OM3 (3 masks for OM4)Must only pass 1 mask to be OM3 (or OM4) compliant

1-2 µm

25%

DMD output is “ Normalized”

Pass = OM3 (2000 MHz.km EMB) or OM4 (4700 MHz.km EMB)Fail = OM2 (< 2000 MHz.km EMB)

Characterization MethodsDMD (differential mode delay) Mask



T delay

Fiber Core

Fiber Core

≈5µm

TSlowTFast

1 of 2 DMD-based standards compliant measurements

Simulates several laser types scanned across core

BW defined by most delayed pulse

Different laser

characteristics simulated“ Hot outside” laser

Laser

“ Mid-range” laser

“ Hot inside” laser

Laser

Laser

Laser Laser

Laser Laser

Laser

Laser Laser

Laser Laser

Laser

Laser Laser

e.g. VCSEL #5Bandwidth value= 3128 MHz.km




e.g. VCSEL #1Bandwidth value

= 2137 MHz.km

e.g. VCSEL #1Bandwidth value

= 2137 MHz.km= 2137 MHz.km

minEMBc Value

Note: BW values provided for illustrations purposes only, drawing not scale

Characterization MethodsminEMBc (min Effective Modal BW – calc)



In-Building Backbone

• 80% fiber and increasing• 35% 1 Gb/s - 65% 100

Mb/s

• Multimode fiber

dominates, OM3 preferred

Campus Backbone

• 95% fiber and increasing• 10 Gb/s initial deployments

• 70% 1Gb/s - 25% 100Mb/s

• Fiber preferred, single-

mode fiber continues to

gain

Data Centers• 60% fiber and increasing

• 1, 2, 4, 8 and 10 Gb/s

• Multimode fiber dominates,

OM3 strongly preferred

Horizontal• Predominately Copper

• 10/100/1000 Mb/s

• Zone (FTTE) fibergrowing

Multimode fiber dominates in risers &

data centers

Source: Corning Analysis



Historically, there have been manybenefits of fiber vs. copper

• Performance

– Higher data rates/

longer link lengths – Low latency

– Network security

– Immune to EMI,

RFI and cross-talk – Longer cable life

• Pathways and

space

– Smaller, lighter

cables

Less cable fuel

load

– Easier installation 0 100 200 300 400 500 600

Cat6a

Cat7

Distance (m)

Cat5 10GBASE-T Link Lengths

Cat6

C o p

p e r

0 100 200 300 400 500 600

OM3

OM4

Distance (m)

OM1 10 Gb/s Link Lengths at 850 nm

OM2 F i b e r



With 10G the list of benefits of fibervs. copper is growing

• Electronics portdensity, power and

cooling efficiencies

= GREEN• Cost position

changing with 10G

– TIA Fiber Optic LANCost Model

– Complexities of 10G

copper testing

10 Gb/s Operating CostFiber vs. Copper

Fiber Copper

Power Consumption

Cooling Requirements

Transceiver Size

Data Center Area

~1-4 W

$

~8-10W

$$$$



Active components costs dominateenterprise link economics

Typical 300 meter backbone

• Fixed costs ~ the

same regardless offiber choice

• Transceiver costs ~

¼ of total system

costs

– Key area for savings

with multimode fiber

– Greatly outweighsdifference in single-

mode versus

multimode cable cost

Jumpers,

Connectors

< 1%

Fiber Optic Cable

1%

Patch Panel, Rack

< 1%

Transceivers 24%

Switch Electronics

74%

Fixed Cost

Source: www.foundry.com, www.peppm.org, Corning analysis



Multimode fiber solution saves ~50%over single-mode fiber solution

• Assumptions

– 300 m, 24 fiber count cable

– 24 fiber PassiveInterconnect (x2)

– 18 x 1 Gb/s Transceivers

• Key findings:

– Cable very small portion of

link costs

– MMF 850 nm (SX)

solutions always lower cost

• OM3 fiber

– Supports 10 Gb/s over300m

– Lowest cost upgrade path

to 10G

0

0.5

1

1.5

2

2.5

OM2 OM3 OM-2 (LX) OS-2 (LX)

Relative System Costs: 1 Gigabit over 300m

Fiber Cable Hardware Tx/Rx

1 3 0 0 n m

1 3 0 0 n m

8 5 0 n m

8 5 0 n m

OM4

8 5 0 n m

S i n g l e - m o d e

Small ∆ for

10G capability

LX = Long Wavelength = 1300 nm

850 nm continues to provide cost benefit at 10G and beyond



850 nm continues to provide costbenefit at 10G and beyond

• 850 nm VCSELs ~90% of

optical 1G enterprise market

• 850 nm 10G VCSELs justentering high-volume

manufacturing

– 850 nm continues to be low-cost

solution for 10 Gb/s

– Low cost solutions for 100 Gb/s

have been identified

– SFP+ 850nm transceivers

continue to drive price down

• LR (1300 nm) solutions maycapture some market share in

enterprise networks

– Small percent of new installs

10 Gb/s Transceivers

Source: Corning estimates

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

2003 2005 2007 2009 2011

Time

R e l a t i v

e C o s t

850nm

1300nm



North American market now majority50 µm

Source: Burroughs Report

More 50 µm sales than 62.5 µm sales since Q1 2008

Multimode Fiber Market Demand

30%

35%

40%

45%

50%

55%

60%

65%

70%

Q1 2005 Q1 2006 Q1 2007 Q1 2008 Q1 2009 Q1 2010

50 µm 62.5 µm



Laser-Optimized 50 µm continues togrow

Source: Burroughs Report

OM3 has been majority of 50 µm since Q1 2007

50 micron Market Demand

30%

35%

40%

45%

50%

55%

60%

65%

Q1 2005 Q1 2006 Q1 2007 Q1 2008 Q1 2009 Q1 2010

OM2

OM3/OM4





Part II• Next generation multimode fibers and

standards – OM4 and next generation speeds (16 Gb/s, 40 Gb/s

and 100 Gb/s)

– Bend-insensitive multimode fiber



OM4 standard approved by TIAin August, 2009

• OM4 is 50 µm fiber with higher effective modal bandwidth than OM3

– Extra bandwidth can be used for higher bit rates, longer link lengths or

increased margin for more connectivity

• Existing “OM” designations (per ISO/IEC 11801) are shown in the table

below

• IEC proposal for OM4 has yet to be approved but highly likely it will be

harmonized with TIA

550 m

300 m

82 m

33 m

10 G Link

Length

100 m1500/500200050OM3

50

50

62.5

Core

Diameter

(µm)

150 m3500/5004700OM4

-500/500-OM2

-200/500-OM1

100 G

Link

Length

OFL 850/1300

(MHz.km)

EMB

(MHz.km)

“OM”

Type



Parallel optics are preferred formultimode fiber objectives

40 Gb/s

• 4 fibers x 10 Gb/s for transmit

• 4 fibers x 10 Gb/s for receive

• One 12 fiber ribbon

100 Gb/s

• 10 fibers x 10 Gb/s for transmit

• 10 fibers x 10 Gb/s for receive• Two 12 fiber ribbons



• The standard supports 40 Gb/s over:

– At least 10km on single-mode fiber

– At least 100m on OM3 MMF – At least 150m on OM4 MMF

– At least 7m over a copper cable assembly

– At least 1m over a backplane

• The standard supports 100 Gb/s over: – At least 40km on single-mode fiber

– At least 10km on single-mode fiber

– At least 100m on OM3 MMF

– At least 150m on OM4 MMF – At least 7m over a copper cable assembly

IEEE approves 40G/100G standard

OM3 100 meter distance allows for 1.5 dB of connector loss

OM4 150 meter distance allows for 1.0 dB of connector loss



Value proposition for OM4 dependson application

• Significant value for OM4 at 10G Ethernet

• Little value for OM4 at 4G regardless of EMB value – Dispersion limited because of broad spectral width

• 16G has tighter spectral width than 4G so value increases

• Although 40G/100G is based on 10G arrays, looser specifications for 40G/100G

transceiver arrays significantly reduce the value

10G Ethernet

40/100G Ethernet

16 G Fibre Channel

4G Fibre Channel

System Operating Link Length vs Laser Bandwidth

0

100

200

300

400

500

600

2000 2500 3000 3500 4000 4500 5000

Laser Bandwidth EMB (MHz.km)

L i n k l e n g t h ( m )

O

M 4 B e n e f i t

Applicat ions

OM3 OM4



OM4 at 40G/100G extends costeffective MMF solution

• Objective of at least 100 m

on OM3 covers ~ 70% ofdata center links

– Reducing connector loss to

same level as OM4 allows

OM3 to support 120 m

• Extending OM4 distance to

150 m with existing

transceivers covers ~ 90%

of data center links

• OM3 and OM4 fibers can

support even longer

distances, but transceiver

spec change is required

Source: Corning Cable Systems

0 50 100 150 200 250

Cable Length (m)

R e l a t i v e F r e q u e n c y

0%

20%

40%

60%

80%

100%

C u m u l

a t i v e F r e q u e n c y

Length Distribution Cumulative Frequency



Over time, MACs lead to mis-

managed cabling resulting in:• Congestion in sub-floor space

• Bend-induced attenuation

• Restricted air flow

• Negative impact on cooling efficiency

Moves, adds and changes (MACs) can

cause a structured cabling system tolook more like a rats nest

Initial installations that follow

bend radius guides andstructured cabling paths don’thave to worry about signal lossdue to inappropriate bends

However…



Data center “ wish list” points toneed for effective cable management

• Increase density of factory-

terminated solutions• Improve slack management

• Relieve congestion in pathwaysand spaces

• Improve airflow

• Eliminate polarity concerns

• Improve MACs



15 years10%NETWORKCABLING

3 years20%SERVERS

3 years30%COMPUTERS

5 years40%SOFTWARE

ExpectedLifespan

Percentage ofOverall Cost

Element

Source: Datalan-Network-Infrastructures

Poorly installed cabling can degradenetwork performance

• Cabling is a relatively small

fraction of the initial network

spend

• Cabling has the longest

expected lifetime of the major

network elements

• The potential for network failure

due to poor cabling is high

• Cabling is often an “afterthought”

but it shouldn’t be

– Key to ensure that the cablingwon’t become the most

expensive part of the network



Fundamentals of macrobendingin multimode fiber

• Multimode fiber has many modes of light traveling through the core

• As each of these modes moves closer to the edge of the core it is

more likely to escape, especially if the fiber is bent

• In a traditional multimode fiber, as the bend radius is decreased, the

amount of light that leaks out of the core increases

Dissipation ofenergy

Core

Cladding



Bend-insensitive multimode fiber prevents light from escaping

• A specially engineered optical trench can be used to trap the energy

in the many modes which propagate within the fiber core

• Keeping the light in the core, even in the most challenging bending

scenarios, significantly reduces the bend-induced attenuation

Energy is confined inside the fiber Trench acts like barrier



Standard OM3/OM4 fiber versusbend-insensitive OM3/OM4 fiber

Up to 10x better bend performance than

standard 50 µm fiber

High bandwidth OM3 and OM4capability

Improved optical performance

Fully standards compliant; Compatible

with installed base

May be spliced/ connectorized with

commercially available equipment

0.01

0.1

1

10

5 7 9 11 13 15 17 19 21 23 25

Bend Radius (mm)

M a c r o b e n d l o s s

, 8 5 0 n m ,

2 t u r n s ( d B )

B e nd - I ns e ns i t i v e O M 3 / 4 F i b e r

S t and ar d O M 3 / 4 F i b e r

1 dB0.5 dBMax Induced Attn @ 850 nm

0.05 dB

100

37.5 mm

Multimode Std

IEC 60793-2-10

Proposed BI Fiber Spec @ 850 nm

Number of Turns

Bend Radius

0.2 dB

2

7.5 mm

New Level of BendPerformance

0.1 dB

2

15 mm

Multimode Std

ITU – G.651.1



Typical Storage Area Network (SAN)link includes > 30 bends



Bend-insensitive OM3 fiberincreases the spare margin

Protected “Headroom” or Spare

Operating Margin

0

1

2

3

4

Conventional

OM3 fiber with bending

Loss

due tobending

Chromatic

Dispersion

Improved

Attenuation

Bend insensitive

OM3 fiber with bend

T o t a l I n

s e r t i o n L o s s ( d B )

Max IL and Margin for 300 m 10G link

Increase Spare

System Margin

Protect Link

Power Budget

Benefits of Bend-Insensi tive OM3



Reliability is Key Concern forSystem DesignersCause of Downtime

Cost of Downtime

• Cables and connectorsaccounted for 6% of downtime

• Structured cabling can effect

43% of network downtime

• Cost of downtime varies based

on organizational size• Network degradations are

more difficult to trace



Bend-insensitive multimode fiber

enables better “ box”

• Key benefits:

• Smaller, lighter, more compact cables, hardware and equipment designs

• Reduced data center footprint

• Better cooling/airflow; Reduced energy usage

• Supports Green Data Center

• Lower OPEX

A B

Size of “box” with

conventional 50

µm fiber

Size of “box” with

bend-insensitive

50 µm fiber

Loss of A = Loss of B

Drawing To ScaleSubstitute bend-

insensitive multimode

fiber for conventional

50 µm fiber



Make connector side-pulls anon-event

Standard 50 µm fiber Bend-insensitive 50µm fiber



Keep your network clear withbend-insensitive multimode fiber

Standard 50 µm fiber

Bend-insensitive 50µm fiber



Summary• Multimode fiber remains the most cost-effective choice

for enterprise networks

• Bend-insensitive multimode fibers can help solve key

concerns of enterprise network operators

• OM4 fibers are now standardized and provide a path for

extended distances for next generation speeds

• Next generation standards will use OM3 and OM4 fibers

to provide low cost future-proof solutions for enterprise

networks

Documents

Why Cable Bends