2010 CT - Ch 11 PP - Introduction to Fiber Optic Networks.ppt

7/27/2019 2010 CT - Ch 11 PP - Introduction to Fiber Optic Networks.ppt

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www.greenITcenter.org DUE 0903239

Chapter 11

Optical Networks
http://www.greenitcenter.org/http://www.greenitcenter.org/


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www.greenITcenter.org

Objectives

Define Optical Networking

Define the components of a fiber optic system

Define characteristics of fiber optic cable

Describe Single mode and multi mode fiber

Introduce concepts of wave division multiplexing


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Optical Networking What is it?

In its simplest form, optical networking is

when the data transport is carried via light

over fiber optic cable (as opposed toelectrical impulses over copper cable)


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Components of a Fiber Optic

System

1. Transmitter - takes information such as voice, data, video, encodedinto electrical signals into light signals and sends it down fiber opticcable

2. Fiber optic cable - medium which the signal is carried on

3. Receiver- accepts light signal and converts it back into electricalsignals


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Fiber Optic Cable

Core - central region of optical fiberwhich light travels through andinformation is carried.

Cladding - Made of glass with lowerrefractive index than the core.Causes light in the core to reflect offof the cladding and stay containedin the core

Coating - outer protective coating thatprotects the fiber from damage andmoisture

Reference: Compared

to human hair

70 um!


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Fiber Optic Cable (cont)

Fiber-optic cable (fiber)

Composed of one (or several) glass or plastic fibers at its center(core)

Data transmission Pulsing light sent from laser

LED (light-emitting diode) through central fibers

Cladding

Layer of glass or plastic surrounding fibers

Different density from glass or plastic in strands

Reflects light back to core

Allows fiber to bend


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Fiber Optic Cable (cont)

Plastic buffer

Outside cladding

Protects cladding and core

Opaque absorbs any escaping light

Core and Cladding manufactured as a single piece of silica and cant

be separated from each other

Different varieties

Based on intended use and manufacturerTwo categories

Single-mode

Multimode


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Transmission over single-mode fiber-optic cable

SMF (single mode fiber)

Uses narrow core (< 10 microns in diameter)

Smaller core than MMF

Laser generated light travels over one path

Little reflection

Light does not disperse

Accommodates

Highest bandwidths, longest distances

Connects carriers two facilities

Costs prohibit typical LANs, WANs use

$$$ than MMF

Jumpers are yellow


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MMF (multimode fiber)

Allows more than 1 mode of light

Uses core with larger diameter than single-mode fiber

Common size: 62.5 microns

Laser or LED generated light pulses travel at different angles

Common uses Cables connecting router to a switch

Cables connecting server on network backbone

Transmission over multimode fiber-optic cable

Jumpers are orange


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MMF(cont)

Benefits

Extremely high throughput

Very high resistance to noise

Excellent security

Ability to carry signals for much longer distances before requiring repeatersthan copper cable

Industry standard for high-speed networking

Drawback

More expensive than twisted pair cable

Requires special equipment to splice

Throughput

Reliable transmission rates

Can reach 100 gigabits (or 100,000 megabits) per second per channel


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MMF (cont)

Cost Most expensive transmission medium

Connectors ST (straight tip)

SC (subscriber connector or standard connector) LC (local connector)

MT-RJ (mechanical transfer registered jack)

Noise immunity

Unaffected by EMI

Size and scalability Segment lengths vary

150 to 40,000 meters

Due primarily to optical loss


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Connectors

ST Connector SC Connector

MultimodeSingle-Mode


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Transmitters

Accept coded electronic signals, process them to light signals andthen send them off onto the fiber cable

Light signals generated by LEDs or lasers

Different light sources have different wavelengths (lambda)

Transmitter designed to emit 850, 1310 or 1550 nanometers


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Receivers

Other end of the cable receives the incoming light and convertsback into electrical signal

Uses photo detector

Signal quality system performance characteristics

Bit error rates number of errors that occurs betweentransmitter and receiver

Saturation - maximum received power that can be receivedbefore distorting of signal and causing poor performance

Sensitivity - minimum power that must be received on anincoming signal


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Factors that affect fiber optics

Attenuation - loss of optical power as light travels down afiber resulting in a dim signal. Measured in decibels. Canbe caused intrinsically (such as inside the fiber itself due

to the glass in the manufacturing process), or extrinsic(such as caused by outside factors like bending the fiber)


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Factors that affect fiber optics

Saturation - signal is too bright causing receiver not toreceive the signal properly

Dispersion - spreading of light as it travels down the fiberoptic cable and causing the signal to overlap and besmeared making the receiving unable to determine distinct0 and 1s.


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Wave Division Multiplexing

A method for multiplexing multiple optical carrier signals on asingle fiber by using lasers that emit different wavelengths(colors) to carry different signals

2 types Coarse WDM

Dense WDM


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Comparing DWDM and CWDM

http://www.ciena.com/files/Optical_Networking_for_Dummies.pdf


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Comparing DWDM and CWDM (cont)

CWDM and DWDM uses different technologies with differentproperties

CWDM channels are different than DWDM channel

CWDM is lower capacity and lower cost than DWDM

CWDM is used for short range communication (50-80km)

DWDM is used for long haul

CWDM has fewer channels


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Typical WDM Scenarios

http://www.ciena.com/files/Optical_Networking_for_Dummies.pdf


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References

Corning Fiber 101Tutorialhttp://media.corning.com/flash/opticalfiber/2008/fiber101/fiber101.html

Sura Optical Networking Cookbookhttp://www.sura.org/info_tech/opcook/opcook.pdf

Ciena Optical Networking for Dummieshttp://www.ciena.com/files/Optical_Networking_for_Dummies.pdf

Dean, Tamara. Network+ Guide to Networks
http://www.greenitcenter.org/http://media.corning.com/flash/opticalfiber/2008/fiber101/fiber101.htmlhttp://www.sura.org/info_tech/opcook/opcook.pdfhttp://www.ciena.com/files/Optical_Networking_for_Dummies.pdfhttp://www.ciena.com/files/Optical_Networking_for_Dummies.pdfhttp://www.sura.org/info_tech/opcook/opcook.pdfhttp://media.corning.com/flash/opticalfiber/2008/fiber101/fiber101.htmlhttp://www.greenitcenter.org/


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Credits

Diagrams: Corning online tutorial

Networking for Dummies

Karen Cheng

Photo: Pete Brierley


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This material is based upon work supported by the National Science Foundation under

Grant No. 0402356. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the

author(s) and do not necessarily reflect the views of the National Science Foundation

Questions?

Feel free to contact the creator of this material

Karen Cheng, Associate Professor, Collin College

[email protected]

Documents

2010 CT - Ch 11 PP - Introduction to Fiber Optic Networks.ppt