Fibers Future Requires Clarifying Test Methods

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Fibers Future Requires Clarifying Test Methods

• Christian Schillab
• Product ManagerInfrastructure SuperVision
• Fluke Networks Euope
• christian.schillab_at_flukenetworks.com

N E T W O R K S U P E R V I S I O N
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Optical Fiber Standards Drivers

• IEEE Applications
• Gigabit Ethernet
• 10 GbE
• Ethernet in the First Mile (EFM)
• 40 GbE being discussed
• Cabling
• EIA/TIA TR-42
• International ISO11801 / IEC 86A / WG3
• Data Centers (driven by IEEE)
• Industrial (Fiber deployment driven by copper
  cable susceptibility to interference)

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Increased use of fiber optic cabling

• Greater than 90 of design proposals for larger
  systems specify fiber optic cabling in backbone
  segments.
• 100 Mb/s to the desk is common and requires
  higher bandwidths in the backbone.
• Campuses, connections to WANs and data services
  warrants higher bandwidth pipes.
• New cabling architectures use optical fiber

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Telecommunications Enclosure
TR
Tiny TR
Backbone
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Zoned Cabling with a Telecomm Enclosure
Optical Fiber Backbone
HC in the TR
LEGEND
Fiber Backbone Cable Horizontal Cable
Telecommunications Outlet/Connector Teleco
mm Enclosure with a switch Building Pathways
and Spaces Horizontal Cross-Connect
Telecommunications Room
HC
TR
Offices
Cubicles
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Data Rates of Fiber Technologies
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Maximum Distances for MM Fiber Technologies
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MM Fiber Technology Cabling Loss Budgets
1000BASE-SX and 10GBASE-S using 50 um cabling
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TR-42.8 Study Group

• Proposal by RIFOCS
• Initiated in March 2001
• Chair, Dennis Horwitz also chair of FO-6.1
• BICSI Survey requested August 2001
• Understand needs of end-users, designers and
  installers

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685 valid questionnaires returned
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Certification Testing
What application(s) are you installing on fiber
links today (e.g. GbE, etc.)?
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Certification Testing
What do you use for testing fiber links today?
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Europe expected to be different
What do you use for testing fiber links today?

• European response expected to be not
  representative
• Assumptions based on additional sources
• 1. OTDR
• 2. OLTS
• 3. Power Meter (closely following)

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Certification Testing
Are you confident that present optical fiber
testing will support your application?
Is there an industry-need to clarify optical
fiber testing?
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Certification Testing
Where are you getting your information on how to
perform fiber optic link testing?
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TIA TR-42.8 Action on Testing

• Create an information document to specify testing
  and explain the proper test procedures
• TSB140, Additional Guidelines For Field-Testing
  Length, Loss And Polarity Of Optical Fiber
  Cabling Systems
• The scope describes field testing of length,
  optical loss and polarity, in optical fiber
  cabling using an optical loss test set (OLTS),
  optical time domain reflectometer (OTDR) and a
  visual fault locator (VFL)

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Two-Tier Testing Specification

• Tier 1 OLTS
• Conform to TIA-526-14A and TIA-526-7
• Most closely simulate system
• Verify polarity using OLTS or VFL
• Tier 2 Tier 1 plus OTDR trace
• Evidence that cable is installed without
  degrading events (e.g., bends, connection, splice)

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Sources of Loss in Fiber Optic Paths

• The fiber material
• Impurities
• Variation in material density
• Coupling losses between fibers
• Dirty connections
• Severe bends in the fiber

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Complimenting Test Tools

• OLTS most closely emulates system to be installed
• OTDR ensures quality installation
• No added splices
• No added connections
• Consistent connections
• No stressed cable (bends, tight cable run)

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OTDR
OLTS
Direct measurement of light
Indirect measurement of light
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Cabling Certification Maintenance

• Primary functions of Certification Cabling Test
  Equipment
• Certify Document for proof of performance to
  Industry Standards.
• US, European or other region specifications for
  structured cabling standards
• Application specific physical media performance
  requirements such as 10GBASE-S
• Maintenance/Service
• moves, adds, changes and troubleshooting

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Tools typically used when certifying

• Visual fault locator (VFL)
• Certify polarity
• Optical loss test set
• Certify power loss on fiber link
• Optical Time Domain Reflectometer (OTDR)
• Certify installation quality
• Video microscope (not part of the TSB)
• Certify connector installation quality

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Visual Fault Locators (VFL)

• Verify polarity
• Identify high losses
• Cable
• Fiber
• Connectors

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Certifying with an OLTS

• Most closely emulates system to be installed
• Available for LED, laser, and VCSEL
• Requires referencing the power meter to the light
  source
• Two technicians are needed

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Certifying with an OLTS

• Automatic testing of both fibers in two
  directions at 850 nm / 1300 nm, 1310 nm / 1550 nm
  wavelengths
• Automatically calculates loss budget and
  pass/fail limits based on fiber test standards
• Provides documented certification of test results

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OLTS in the TSB

• Method B (multimode)
• Method A.1 (singlemode)
• Coupled Power Ratio
• Categories
• Mandrel wrap
• Removes high-order modes

Cladding
High-order mode
Low-order mode
Cladding
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Test Methods

• ANSI/TIA/EIA-526-14A
• Method A
• Method B

Access Providers (OSP)
Buildings (Premises)
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Access Providers (Method A)

• Referencing

850 nm 1300 nm
Source
Meter
Connector
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Access Providers (Method A)

• Reference

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Access Providers (Method A)

• Cable Test

Measures cable plus one connection
850 nm 1300 nm
Source
Meter
Connection
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Buildings (Premises)(Method B)

• Referencing

850 nm 1300 nm
Source
Meter
Connection
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Buildings (Premises)(Method B)

• Reference

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Buildings (Premises)(Method B)

• Cable Test

Measures cable plus two connections
850 nm 1300 nm
Source
Meter
Connection
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Example of the Methods
Cross Connection in the TR (2 connections) Connect
ion in the ER (1 connection) Connection at the
wall outlet (1 connection) 300 feet of 62.5 ?m
fiber at 850 nm 0.31 dB
Horizontal Cables
Access Provider 3 connections _at_ .75 dB plus .31
dB for cable 2.56 dB Building 4 connections
_at_ .75 dB plus .31 dB for cable 3.31 dB
Backbone Cables
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Certifying with an OTDR

• Second tier of testing
• No referencing
• One technician needed
• Provides documented certification of test results
• Results may be interpreted into a table

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OTDR not ideal for loss measurement

• Sends out a light pulse
• Looks at light scattered back
• Can determine location of an event

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OTDR Technology

• Rayleigh Scattering
• Fresnel Reflection

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Rayleigh Scattering
Scattering, (Rayleigh Scattering) occurs when
transmitted light energy is higher than what the
glass molecules can absorb and the energy is
released in all directions. It is the major loss
factor in fiber.
Backscattering occurs from about 0.0001 of the
light being reflected back to the OTDR.
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Fresnel Reflection
Coupling loss air gap causes loss of light
transmitted
Fresnel Reflection occurs when light traveling in
one material encounters a different density
material (like air). Up to 8 of the light is
reflected back to the source while the rest
continues out of the material.
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Basic Trace Diagram of Fiber Loss and Events of
a Connection and a Splice
Connectors show both loss and reflections (Resnel
Reflection)
Events
Slope of trace shows fiber attenuation
coefficient (Rayleigh Scattering)
Splices are usually not reflective
Splice loss
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OTDR Operation
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Lower your Losses using an OTDR

• Detect stressed fiber
• Tightly run cable
• Severe bends in cable runs
• Detect bad connections
• Air gaps
• Dirt

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Losses From Dirty Connections
Good Connector
Fingerprint on Connector
Dirty Connector
Views from Video Microscope
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Clarifying Test Methods

• Use an OLTS to most closely simulate the system
• Use a VFL or the OLTS to verify polarity
• Use the OTDR to identify and locate loss events
• TSB140 is under development in TR-42.8
• Lower your losses using TSB140

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N E T W O R K S U P E R V I S I O N
Fluke Networks is a leading provider of
innovative Network SuperVision Solutions for
ensuring data communications and Internet uptime.
We imagine and deliver kick butt products, that
delight our customers and have fun doing it.
Thank You
Christian Schillab Fluke Networks
Euope 43(664)4310505 christian.schillab_at_flukenetw
orks.com