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10 GbE fiberWhy it is different

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Agenda

What is the difference for LOMM fiber

Understanding what happens in the fiber

Design and Specification for 10GbE fiber

Plug-n-Play Topologies

Installation

Testing

Future

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Leviton 10GbE the Fiber Future

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What is the difference for LOMM fiber

The transmitter

VCSEL (Vertical Cavity Surface Emitting Laser). A VCSEL laser light source emits atthe 850 nm wavelength and it is capable of a high data rate.

An LED and VCSEL emit light differently. In technical terms, the launch conditionsbetween these two light sources are different.

The LED emits light relatively uniformly over the entire face of the multimode fibercore.

A VCSEL source emits light in a narrow beam, which shines bright in the center ofthe fiber core and quickly dims as it moves away from the center; it does notilluminate the core near the cladding interface.

This difference in launch conditions results in different loss measurements. The lossmeasured with a LED is typically greater than the loss measured with a VCSEL.

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Understanding what happens in the fiber

10-Gigabit Ethernet (10-GbE) -A version of Ethernet with a nominal data rate of 10 Gbit/s, agigabit per second (Gbit/s or Gbps) = 1,000,000,000 (10^9) bits per second, 10GbE over fiberis specified by IEEE 802.3. Gigabit Ethernet uses digital signaling. The fiber optic version of

this is 1000BASE-SX.Laser-optimized 50/125 m multimode fiber Multimode fiber cable that is specificallydesigned for 850 nm operation at 1 Gb/s and higher. TIA/EIA-492-AAAC specifies mechanical,geometric and optical characteristics for laser-optimized 50/125 m multimode fiber. This fiberhas been fully adopted into TIA/EIA-568-B.3 and IEC-11801

Differential Mode Delay (DMD)A light pulse launched from a VCSEL will have differentmode groups and will, in general, have different propagation times. This results in bandwidthreduction and limiting of the distance for 10-GbE transmission. However as you can see fromthe following figures, the effect is minimized by use of laser optimized 50 m multimode fiber.

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Understanding what happens in the fiber

The methodology of measuring DMD uses a single-mode pulse ( 5 m spot size) whichis scanned across the 50/125 m laser-optimized multimode fiber core in at most 2 mincrements. Figure X is an illustration of this methodology.

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Understanding what happens in the fiber

Effective Modal Bandwidth (EMB)

The Fiber bandwidth measurement technique to ensure 50/125-m laser-optimizedmultimode fiber will reliably support 10-GbE transmission.

Calculated Effective Modal Bandwidth (EMBc)

The main purpose of the EMBc calculation is to ensure that a fibers effective modalbandwidth will meet the10-Gbits/sec requirement of 2000 MHzkm with anyconforming laser.

Minimum Calculated Effective Modal Bandwidth (minEMBc)

The second method of predicting EMB from DMD.

DMD Mask

Is the translating of DMD data into an EMB prediction.

Return loss

Is the power of the optical signal that returns towards the optical source against thedirection of signal propagation. Contributors to return loss are Fresnel reflections(back reflected light due to interfaces at mated connectors and mechanical splices)and Rayleigh back scattering (scattered light due to intrinsic fiber properties).

Bit Error Rate (BER)

Is the number of bit errors per unit time compared to the total number of bitstransmitted per unit time. Error free propagation of bits of data through the fiberlink is the ultimate design goal of the MMF and connectors in a 10-GbE optical link.

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Design and Specification for 10GbE fiber

Design of a 10-GbE fiber solution should start with the fiber.

The selection of the optical properties of fiber should alsobe carried over to the fiber patch cords and also to the

connector if you will be using a pre-polished connector or

manufactured terminated cabling.

50/125 m laser optimized fiber for building backbone,

campus backbone, horizontal cabling, centralized cabling anddata centers is recommended, so long as it does not exceed

the operating range of 300m (OM3) or 550m (OM4).

This provides the user with the ability to operate at slower

data-rate speeds initially, while additionally offering the

ability to migrate to higher data-rate laser-based systemsas demands for bandwidth increase.

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Plug-n-Play (PNP) Topologies

What are they?

Most common assumptions

Factory terminated modules through the use of a multifiber connector with breakoutkit to individual fiber connectors for discreet interconnect

jumper cassette trunk cable cassette jumper cassette trunk cable cassette jumper

Standard PNP issues

Cassette system component loss @ 1.2dB

Total path loss = 4.8dB

Amount of discreet connections

Future migration requires replacement of cassette or hybrid jumper

Leviton PNP MTP Bracket solution

Reduces component loss to 0.5dB per connection

Reduces number of links hopsResults in total path loss of 2.0dB

Reduces the number of discreet connections (harness vs jumper)

Future migration via use of harness replacement

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Standard PNP Topology

Total Loss = 4.8dB

2.2dB Over Budget

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Leviton PNP Bracket Topology

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Installation

Follow the industry standards for the passive components,

TIA/EIA-568-C, Commerc ia l Bui ld ing Telecommunicat ionsCabl ing Stand ard,

TIA/EIA 569-A, Commerc ia l Bui ld ing Standards forTelecommun icat ions Pathw ays and Spaces, and

TIA-942, Telecommunic at ions Infrastructu re Standard for DataCenters,

These standards offer guidance, recommendations and a templatefor a successful solution.

A final note on the installation of a 10-GbE fiber solution. Fiberconnector and coupler adapter cleanliness and fiber connector endface polish are the most often over looked cause of system failure tosupport a 10-Gbe solution. Make sure to thoroughly clean and

visually inspect all connectors, couplers and patch cords.Additionally bend radius and tension placed on the fiber cable willhave a significant impact on the capacity of a fiber network tosupport a 10-GbE solution. Careful attention to installationmethodology and support hardware is a must.

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Testing

Deployment of high data-rate 10-GbE systems requires attention todetail as cabling length and attenuation requirements are more

stringent.TIA TR-42.8 outlines in TSB-140 outlines the field testing ofoptical fiber cabling.

This document describes field-testing of length, optical loss andpolarity in optical fiber cabling using an optical loss test set(OLTS), optical time domain reflectometer (OTDR) and a visual

fault locator (VFL).

The purpose of this TSB is to clarify, not replace ANSI/TIA/EIA-526-7 and ANSI/TIA/EIA-526-14-A.

Standards, such as the IEEE802.3ae, typically specify the maximumchannel link loss as a primary link parameter. Although measured

installed link loss is an important parameter, the link loss is not atrue indicator of whether or not a fiber is capable of supporting10Gb/s error free transmission. The most precise measure of channelperformance is bit error rate (BER) testing. At this time aneconomical field BER testing device is not available, so you mustrely on conventional link loss testing.

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Future Look

At the time of this paper, the TIA/EIA-492AAAC (850-nm laser-

optimized, 50 m MMF) specification is being asked to review

a new draft specification 492AAAD from the work on the TSB-

172 Committee: TIA FO-4.2 _ TIA TR42.12. This review is

scheduled for 02/08. This new fiber commonly know as OM4

is being considered to handle up to 1000-GbE via 850-nm

laser-optimized, 50 m multi-mode fiber.

The IEEE Higher Speed Study Group (HSSG) has voted to

approve the next standard speed for Ethernet to be 100

Gbit/s. HSSG is currently working on developing the next

generations of Ethernet. It is obvious that optical fiber will be

a significant portion of that future.

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