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The University of Texas at Dallas

OVERVIEW OF OPTICAL COMMUNIC

Notes prepared for EE 63

by

Professor Cyrus D. Cantr

AugustDecember 2003


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EE 6310 OPTICAL COMMUNICAT

EE 6310 surveys:

Technologies and concepts that underlie optical Optics

Optical components and devices

Optical fiber properties and characterization

Digital communications Optical communication systems


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OUTLINE OF COURSE TO

Overview of optical communication systems

Review of optics The characteristics of optical fibers

Optical waveguides

Review of digital communications Optical sources and transmitters


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TOPICS OF THIS LECTU

Why optical communications?

Background for optical communication systems Important optical communication systems and t

Telecom networks vs. data networks

History of data networks and the Internet, st

systems

Internet backbone networks: A planetary scal


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WHY OPTICAL COMMUNIC

Optical attenuation in the 1.3 m and 1.55 m ba

electrical attenuation in any cable at useful modula Much greater distances are possible between o

between electrical regenerators

Bandwidth, bandwidth, bandwidth...

Optical frequencies are much higher than electr

Much higher modulation frequencies great


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BACKGROUND FOR OPTICAL COMMUN

Optics

Laws of reflection & refraction Interference & interferometers

Diffraction & diffraction gratings

Digital communications

Eye patterns & eye masks

S d h l


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IMPORTANT OPTICAL COMMUNICAAND TECHNOLOGIES

Wide-area networks Either government-regulated or in the public ne

WANS originated in telephony

Main technologies: SONET/SDH, ATM, WDM

Voice circuits vs. packets Non-optical technologies (unless encapsulated


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IMPORTANT OPTICAL COMMUNICAAND TECHNOLOGIES

Local-area networks Main technologies: Ethernet, Fast Ethernet, Gi

Currently fiber for backbone, copper for distribu

Excess capacity enhances performance

Access networks


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TELECOM NETWORKS vs. DATA

Telecom networks

Have been around for more than a century Rich in service features for voice communicatio

Switching is used to eliminate the need for direcnodes in the network

Basic unit is the 64-kb/s voice circuit 64-kb/s circuits are multiplexed into higher-bit


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SIMPLIFIED DIAGRAM OF A TELEPH


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THE GOOD OLD DAYS OF TELEC

Analog voice circuits between customers and centr Maximum frequency transmitted: 4 kHz Carried on a single twisted copper-wire pair

Analog inter-central-office trunks: Required repeaters every 2 km

Duct diameter (10 cm) limited the number of c


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Channel1

Channel2

Channel3

Channel4

193-bit frame (125 sec)

7 Databits perchannel

per sample

Bit 1 isa framingcode

Bit 8 is forsignaling

0

1


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THE UNIVERSITY OF TEXAS AT DALLAS E

NORTH AMERICAN DIGITAL H

Digital Signal Transmission Carrier

Designation Rate Designation DS-0 64 kb/s DS-1 1.544 Mb/s T1 DS-2 6.312 Mb/s T2

DS-3 44.736 Mb/s T3 DS-4 274.186 Mb/s T4


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SONET/SDH SIGNAL HIERA

SONET ITU-T Data Rate

Designation Designation (Mb/s) STS-1/OC-1 51.84 STS-3/OC-3 STM-1 155.52 STS-9/OC-9 STM-3 466.56

STS-12/OC-12 STM-4 622.08 STS-18/OC-18 STM-6 933.12


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WHAT IS A DATA NETWO

A data network is a set of logical communicatiocomputers

Used for interprocess communication

Communication among processes running on the same computer

A logical communication channel is an abstractset of one or more physical links, plus software


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Process

Transport

(TCP or UDP)

Network (IP)

UserProces

s

Operating

System

THE DE FACTO TCP/IP PROTOCOL S


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Application

Transport

Virtual Links and Data Unit

Streams and Messages

Packets

Datagrams

Peer-to-Peer Links in TCHost A

Client App


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INTERNETWORKING: WHEN ONE I

Why not have a single physical network for the en

Requires centralized coordination Difficult to integrate heterogeneous networks

Growth by scaling difficult (impossible?)

Alternative: Interconnected networks that look lik

Interconnection can be implemented at layer 3 w


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INTERNETWORKING USING BACKB

A backbone is a network used to interconnect ot

Backbones range from single links to planetary-

Network 1 Network 2


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INTERNETWORKING: LAYER

Layer 1 internetworking: Goal is to connect two sinetworks so that they function as one

Typical internetworking device: Repeating hub

Layer 2 internetworking: Connect two (possibly dissso that traffic flows from one to the other only if n

Typical internetworking devices: Bridge, Layer L 3 i t t ki G l i t t di


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ROUTING IN IP-BASED NET

Routing: The process by which a computer chooto forward datagrams for which it is not the end s

Router: A special-purpose computer that fonext hop, or to their destination, based on informcalled the routing table

Multiaddressed hosts (hosts that have more thanroute datagrams

(


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CONTROL vs. DATAPATH IN R

In a router, the datapath forwards datagrams a

The values of fields in the packet header

The interface on which the packet arrives

Entries in the routing table

The control builds and maintains the routing

Instructions compiled in the operating system The routing protocols (RIP, OSPF, BGP, .


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Control

Datapath

Optical Communication Proto

Block Coding

Framing/Switching


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FormattingInformation source

(analog or digital)Modulator

Synchronization

Digitalsymbols

Digital

waveforms

OPTICAL COMMUNICATION S


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GENERATIONS OF OPTICAL TRANSM


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FIRST-GENERATION FIBEROPTIC TE

Purpose:

Eliminate repeaters in T-1 systems used in inte Technology:

0.8 m GaAs semiconductor lasers

Multimode silica fibers

Limitations:


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SECOND-GENERATION FIBEROPTIC T

Opportunity:

Development of low-attenuation fiber (removal ties)

Eliminate repeaters in long-distance lines

Technology:

1.3 m multi-mode semiconductor lasers Si l d l tt ti ili fib


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THIRD-GENERATION FIBEROPTIC TE

Opportunity:

Deregulation of long-distance market Technology:

1.55 m single-mode semiconductor lasers

Single-mode, low-attenuation silica fibers

OC-48 signal: 810 multiplexed 64-kb/s voice cGbit /


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FOURTH-GENERATION FIBEROPTIC T

Opportunity:

Development of erbium-doped fiber amplifiers Technology (deployment began in 1994):

1.55 m single-mode, narrow-band semiconduct

Single-mode, low-attenuation, dipersion-shifted

Wavelength-division multiplexing of 2.488 Gb/s


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TIME-SHARING SYSTEM

ARPA-funded work beginning in 19623 that led t

Interactive computing and time-sharing Intended to replace batch processing

Cards in, paper out, only one job running a

In time-sharing, each user

sat at a terminal, typed in his/her own program,


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TIME-SHARING SYSTEM

J. C. R. Licklider

Originated the Galactic Network concept A globally interconnected set of computers

could quickly access data and programs from

Headed the ARPA Information Processing Techn

October 1962 Funded the Compatible Time-Sharing System (


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PACKET-SWITCHED NETW

Leonard Kleinrock, 1961

Information Flow in Large Communication Ne First paper on packet-switched networks

Paul Baran, RAND Corp., 19604

Highly interconnected network highly surviv

No single point of failure No small set of points of failure


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ARPANET (1)

Plan originated with Lawrence Roberts in 1967

Purpose was to connect computers over a highly su Funded in 1968 by IPTO

Bolt Beranek and Newman, Inc. (BBN) awardeto build Interface Message Processors (IMPs)

Honeywell DDP-516 minicomputer with 12 K


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ARPANET (2)

First host-to-host protocol was NCP (Network Co

1969 ARPANET had 4 nodes Each node had different host hardware, running

Different interface hardware and network softwa

First email program to send messages across a dist

Adapted by Ray Tomlinson of BBN from an intrad i t l fil t f


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4-NODE ARPANET


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ARPANET (3)

ALOHAnet developed by Norman Abramson, Uni

The first packet radio network Connected to the ARPANET in 1972

Bob Metcalfes Ph.D. thesis outlined the basis for

Concept was tested at Xerox-PARC using Xero

First Ethernet was called the Alto Aloha System


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ARPANET (4)

Vint Cerf and Bob Kahn presented the basic ideas

A Protocol for Packet Network Interconnection Detailed design of a Transmission Control Pr

TCP guaranteed reliable delivery of datagram

The early TCP did not distinguish between TC

IP was separated from TCP (1978) UDP was developed to give users access to unr


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NSFNET

The National Science Foundation (NSF)

Division of Network and Communications Res(1987)

3-tier network

U.S. backbone (NSFNET)

Regional networks

Campus or access networks


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SUCCESSORS OF NSFN

very high performance Backbone Network Service

Partnership of NSF with MCI/WorldCom

Research & education network

OC-3 (155 Mb/s optical) links originally (run

Now OC-12 (622 Mb/s), migrating to OC-48

Internet 2C ti l d b th 180 i iti

A network of firstsA network of firsts

! 1995 - The first IP backbone (running IP over ATM) at OC-3 speed (155Mbps).
http://www.internet2.edu/http://www.internet2.edu/http://www.internet2.edu/


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High Performance Nationwide

Digital Video over

Voice over IP

For more information about products and services,

visit vBNS+ on the World Wide Web:

orcontact:

http://www.vbns.net

Charles LeeAccount Executive, Advanced Networks, Worldcom

8200 Greensboro DriveMcLean, VA 22102

Telephone: 703-902-6254Fax #: 703-902-6011

!

!

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p )

1996 - The first network to measure IP backbone traffic at OC-3 line rateand above.

The first production IP backbone to run native IP multicast and unicast onthe same routers.

The first Internet2 backbone.

The first network to lead nationwide deployment of multicast technologiesat universities and colleges.

The first production network to fully deploy MPLS.

The first nationwide network to offer IPv6 services.

The first network to offer web-based traffic flow reporting.The first network to run high-performance high-bandwidth (>100 Mbps)throughput tests on a nightly basis as a high-performance guarantee.

The first network to publish a study on wide area Internet traffic patternsin a core IP backbone.

The first IP backbone to offer ingress filtering at line-rate.

The first IP backbone to offer 100% network availability with


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IPIPpremier IP networkspremier IP networks

Ou

Thimthema

innIP Mupe

!

!

!

!

!

Enrec

National POPsNew YorkWashington, DCBostonAtlantaHoustonLos AngelesSan FranciscoSeattle

ChicagoClevelandDenverMemphisCleveland

International POPsLondonParisFrankfurtAmsterdamTokyoHong Kong

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Juniper M-40Cisco 7507FORE ASX-1200NAPOC-48 POS TrunkOC-12 POS TrunkOC-12 ATM TrunkOC-3DS-3STM-1

vBNS+ is a specialized nationwide IPnetwork that supports high-performance, high-bandwidthapplications. Originating in 1995 as thevery high performance Backbone

Network Service (vBNS), vBNS+ is theproduct of a five-year cooperativeagreement between Worldcom and theNational Science Foundation.

Now business can experience the samespeed, performance, and reliabilityenjoyed by the Supercomputer Centers,Research Organizations and AcademicInstitutions. vBNS+ customers can takeadvantage of an array of advanced IPnetwork services supported by a high-speed IP backbone. This impressivepackage makes vBNS+ unparalleled fortoday's most demanding customers andtheir applications.

Physically separate from today'scommodity Internet, vBNS+ employs anOC-48 (up to 2.4 gigabits per second)MPLS-based backbone topology,anchored by the world's most advancedIP router platform, the Juniper M40.This combination enables Worldcom tooffer and guarantee one of the bestService Level Agreements (SLA) in theindustry. The vBNS+ network providescustomers with an impressive number ofcutting edge IP services.

hi h f B kb N t k


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THE COMMERCIAL INTE

There are now many commercial backbones

Can be visualized using Mapnet

The owner of a commercial backbone is an ISP

Traffic is exchanged between backbones at peer

Enables a customer of one carrier to send p

another carrier
http://www.caida.org/tools/visualization/mapnet/http://www.caida.org/tools/visualization/mapnet/


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PSINet


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EUNet


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CompuServe


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BBN Planet


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AT&T WorldNet

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