Optical Fiber Data Center Field Testing. ANSI/BICSI Data Center Design and Implementation Best Practices

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1 Optical Fiber Data Center Field Testing ANSI/BICSI Data Center Design and Implementation Best Practices

2 Abstract Data Centers are a growing segment of the enterprise market. Regardless of whether the data center is an offsite company providing storage for one or more companies or the data center is the onsite central storage facility for an individual company the storage and access to the data is generally mission critical. Downtime in a data center or time to turn-up a data center circuit can cost significant dollars. The high speed networks require more stringent performance than typical LANs. To be sure the data center networks will support today s networking applications it is important to properly clean, inspect and test optical fiber networks. What tests are required and recommended for channels and links per the ANSI/BICSI and other standards; End Face Inspection, Optical Loss Testing, Polarity Verification, Optical Return Loss, and Fiber Characterization using an OTDR with both launch and tail cords. 2

3 Requirements Cleaning and Inspection Tier 1 testing with an Optical Loss Test Set (OLTS) Polarity verification Length verification Tier 2 testing with an Optical Time Domain Reflectometer (OTDR) Recommendations Tier 2 OTDR testing Reflectance Optical Return Loss (ORL) Length Outline- Data Center Testing 3

4 Fiber Safety Issues Laser Eye Safety Fiber Scrap Shards from fiber prep Puncture and Cut issues Ensuring all systems are off

5 Causes of Optical Network Failures Why is Test and Inspection important Prevent, detect, & resolve leading causes of optical network failures Contaminated, damaged, or poorly polished connectors Poor splices Micro- or Macro-bends induced in shipping or installation Verify quality of new optical fiber installations Diagnose, repair, and verify optical networks after activation Causes of Optical Network Failures As reported by: Source: NTT Advanced Technology

6 Standards and Requirements 6

7 Data Center Requirements TIA 942-A Data Center Standard Standardizes LC connectors for 1 or 2 fibers MPO connectors for more than 3 fibers Removes OM1 and OM2 fiber support Requires a minimum of OM3 fiber Recommends OM4 fiber or single-mode Eliminates the 100m horizontal cabling restriction Length restriction is now application based 7 AFL Company Confidential

8 Data Center Requirements ANSI/BICSI Data Center Design and Implementation Best Practices Tier 1: OLTS- OPM and OLS attenuation measurement- Required Attenuation Polarity Length if capable Tier 2: OTDR measurements Required Characterize Anomalies with traces Evaluate uniformity of connections (Loss of splices & connectors) Use manufacturers mean insertion loss of components to calculate link budget Inspection and Cleaning Required Other measurements Recommended OTDR: Fiber Length, Reflectance, ORL VFL: Polarity 8 AFL Company Confidential

9 Link Certification Tests and Test Equipment TIA/EIA 568-C.0 Annex E Tier 1 -- Required Link Insertion Loss Link Polarity Link Length OLTS (Certification Test Set or light source and optical power meter) OLTS or VFI (red laser) Can be verified by inspection (of cable markers) or measured using a Certification Test Set or OTDR Tier 2 -- Going beyond the minimum TIA specs Link baseline trace Connection or splice insertion loss Connection or splice reflectivity OTDR OTDR OTDR

10 Value / Features What test equipment options do I have? Visual Fault Locators/Inspection LS/PM & OLTS (Tier 1) OTDR & *OLTS (Tier 1 & *2) MT Tracer MPO Tester Certification Test kit OTDR/ Certification Test Kit FOCIS VFI s Light Source Power Meter OTDR w/ Light SOurce Product category 10

11 Cleaning, Inspection and Polarity Required

12 The Connector End-Face Inspection Verify no energy with power meter First Be sure to clean both connectors prior to mating to prevent moving the dirt between connectors One-click cleaners are easy, fast and effective; enabling user to clean patch cords and through bulkheads in patch panels

13 The Connector End-Face Inspection Inspect connector end-face for: Scratch goes near the core! Dirt Dirt particles Oil Scratches Epoxy Body Oil Don t touch the connector endface! Clean MPO end-face!

14 Inspection always required Live Image Snapshot Image Review

15 Basic Light Test Continuity/Polarity Visual Fault Identifier/Locator (VFI/VFL) Visually see breaks and faults Enables user to locate events that are too close together or too close to the OTDR (limited to 4 km range) Fiber polarity check

16 MPO Polarity check MPO trunk cables why polarity matters MPO-MPO trunks are typically one of three Methods: A, B or C Keying assures proper orientation of the MPO Keying does not assure proper polarity or Method Users should select one method for their networks to avoid polarity issues Method A 16 Source: Opticonx

17 MPO Polarity check MPO trunk cables why polarity matters Tracer / Tester can be used to trace polarity problems Visible light is sequentially injected into one end of the MPO trunk and the MT Tracer indicates which fiber it exits 17

18 MPO Polarity check MPO trunk cables why polarity matters Method A Straight through trunks; key-up to key-down adapters Patch cords: One end A to B straight thru One end A to A pair flipped Method B Straight through trunks; key-up to key-up adapters Patch cords: Both ends A to B straight thru Method C Pair flipped trunks; key-up to key-down adapters Patch cords: 18 Both ends A to B straight thru

19 Data Center Testing Tier 1 & Tier 2 Required and Recommended

20 Attenuation: Decrease in Optical Power Insertion Loss Measured in decibels (db) Limits the distance the signal travels Some attenuation is inherent in glass Connectors can be the single largest contributor to attenuation in the Data Center Some attenuation can be induced by people and the environment Signal below receiver threshold which is a 1 is read as a 0

21 Tier 1 test and OPM Applications Use the OPM function and OLS (MM/SM light source) to measure link loss in dbm/db measure optical power levels of electronics interchangeable adapters allow for 1 jumper reference method

22 Certification Test Set Measures Attenuation Length Checks Continuity Polarity Test Multiple wavelengths in two directions Two fibers at a time Capable of supporting end-face inspection

23 Tier 2 Testing and Characterization Why use an OTDR? Generates a baseline trace A visual characterization of the link - Measure Loss - Measure Reflectance - Measure Optical Return Loss - Measure Length Fiber acceptance tool Documentation Fault location tool Identify and evaluate specific events/problems in the link 23

24 Tools to meet Data Center Test Needs What s important to look for in an OTDR Data Centers have many connections and use short jumpers Very short dead-zones are required to characterize fibers and fault find Attenuation Dead Zone less than 3 m Event Dead Zone less than 1 m 24

25 Tools to meet Data Center Test Needs What s important to look for in an OTDR Easy to Use Interface such as Touch-and-Test TM Simple Job setup and renaming capability of results Auto set up modes to enable novices to get accurate and complete results Front Panel/First Connector checks to assure a quality launch is achieved Easy to define Launch and Tail cords which should be used to obtain link loss measurements Software to help the user find installation errors Macro/Micro-bends Pass/Fail Thresholds 25

26 Tools to meet Data Center Test Needs What s important to look for in an OTDR Multi-functionality in a Easy-to-use platform OTDR Optical Power Meter Visible Fault Locator Support for an Inspection probe Documentation software 26

27 Reflectance (-db) Reflectance: the ratio of reflected light to incident light at a point A concern in networks operating 10, 40 or 100GbE Reflectance is directly impacted by termination technique OTDRs best-suited to measure individual reflections of components in a fiber system and identify them as Events 27

28 Fresnel Reflections (Light reflected at changes in index of refraction) End of a cleaved fiber Two mated connectors Un-terminated connector Mechanical splice How an OTDR Works Air gap at poorly mated connectors Height (db) Appears as a sharp spike in the waveform, OTDR trace Cursor positioning is important in measuring location and loss of a reflective event Height of a reflective event relative to backscatter is its Reflectivity 28

29 Reflectance and Optical Return Loss (-db) Optical Return Loss (ORL): the ratio of the average reflected light from the entire fiber, measured at the launch point, to the average incident power level injected into the fiber at the launch point A high reflectance at the far end of a long fiber won t contribute much to ORL A high reflectance at the near end of a long or short fiber will be the primary contributor to the overall ORL 29

30 How an OTDR works: Tier 2 Testing Relative Power (db) P IN C1 Fiber C2 C3 S1 P OUT Distance The OTDR provides specific loss and distance measurements to all events that are in the link Event = Connection (C), Splice (S) or other anomaly in the fiber system 30

31 Importance of Launch and Tail Cords Should be at least 100m Are necessary to: Characterize the near and far end connectors Provide a Link Loss Measurement 31

32 Documentation - Certify against Industry and/or User cabling standards Pass and Fail results Displays headroom Qualify network applications Event table (OTDR) Cable & Route Summaries End Face Image Thumbnails 32

33 What s Important: Cabling Standards Telecommunication Industry Association (North America) TIA-568 ANSI/BICSI Data Center Design and Implementation Best Practices- European Committee for Electrotechnical Standardization CENELC EN50173 International Organization for Standardization / International Electrotechnical Commission ISO/IEC Optical fibre type size and grade Multimode 62.5µm (OM1) Wavelength Multimode 50µm (OM2) Multimode 50µm (OM3) Multimode 50µm (OM4) Singlemode (OS1) Singlemode (OS2) Fiber attenuation coefficient (db/km) Minimum modal bandwidth (MHz-km) ns N/A N/A N/A N/A Event Type Connector Multimode Connector Singlemode Fusion Splice Max Loss * (db) Reflectance (db) ORL (db) (UPC) (UPC) - 60 (APC) *For Data Center component insertion Loss use manufacturers values (db) 26

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