Chapter

6

Chapter

Module 6A Telecommunications

Module 6B Networks

6

6

TelecommunicationsTelecommunications

Understanding the Telephone System Modems: From Digital to Analog & Back

Digital Telephony: Living with Twisted Pair

Alternatives to Digital Telephony Convergence: Is It a Phone or a Computer?

Module

A

6

Module

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Understanding the Understanding the Telephone SystemTelephone System

Public switched telephone network (PSTN)

Telecommunications

Learn more about the PSTN and fast-breaking new telecommunications technologies? PhoneZone.com’s tutorials.

analog system based on standards that date back more than a century

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Module

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Understanding the Understanding the Telephone SystemTelephone System

Telecommunications

Fiber Optics Online is a trade journal specializing in fiber optics industry; this is a great site to learn about new technologies.

Quality of Service (QoS) Local Exchange Carriers (LECs)

local access & transport area (LATA)twisted pairlocal loop

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Long-Distance Long-Distance Transmission MediaTransmission Media

If you place a call outside the local transport area, an interchange carrier (IXC)—a long-distance telephone company—comes into play

Telecommunications

Transmission facilitiescopper wire fiber-optic cablesmicrowavessatellites

Fiber optic cables consist of thin strands of glass that transmit data by means of pulses of light.

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Standards and RegulationsStandards and Regulations

StandardsInternational Telecommunications Union (ITU)

Universal service Common carrier immunity Deregulation

Regional Bell Operating Companies (RBOCs)

Module

A

Telecommunications

The home page of Pacific Bell, a RBOC, is packed with information and tutorials about cutting-edge

telecommunications services.

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More Ways to Access More Ways to Access the Systemthe System

Telecommunications

Private Branch Exchange (PBX)

Cellular telephones Leased lines

Cellular telephones enable subscribers to place calls via a wireless

communications system.

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The PSTN in PerspectiveThe PSTN in PerspectiveTelecommunications

As a caller moves from one area to another, a new cell site steps in to keep the signal strong. The sites are connected to a Mobile Telephone Switching Office (MTSO), which is connected to the standard PSTN telephone system.

Sender of callreceiver of call

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Telecommunications

A modem transforms the computer's digital signals into analog tones that

can be conveyed through the telephone system.

How modems workmodulationdemodulationinternal modemexternal modem

sender

receiverTelephone lines use analog transmission

Modems: Modems: From Digital to From Digital to Analog & BackAnalog & Back

Modem 1

Modem 2

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Module

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Modems: Modems: From Digital to From Digital to Analog & BackAnalog & Back

Telecommunications

Asynchronous Communicationasynchronous: used by modemssynchronous

Modulation Protocolsdata transfer ratebits per second (bps)V.90 maximum rate of 56 KbpsV.34 maximum rate of 28800 bpsfall back

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FaxFaxTelecommunications

Facsimile transmission enables you to send an image of a document over the telephone lines

to anyone who has a fax machine. If your computer has a fax modem, you can send and

receive faxes from your computer.

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Module

A

Digital Telephony: Digital Telephony: Living Living with Twisted Pairwith Twisted Pair

Telecommunications

Bandwidthmeasured in Kbps, Mbps, or Gbps

Last mile technologiesIntegrated Services Digital Network (ISDN)Digital Subscriber Line (DSL)Synchronous Optical Network (SONET)

BellSouth is one of the first RBOCs to offer ADSL service. Follow the links to FastAccess to learn more.

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Alternatives to Digital Alternatives to Digital TelephonyTelephony

Telecommunications

In contrast to twisted pair, it’s easy to achieve very high bandwidth data communication with coaxial cable.

Direct Broadcast Satellite (DBS)

Cable Modemscoaxial cable

Electrical Power Systems

6

Convergence: Convergence: Is It a Phone Is It a Phone or a Computeror a Computer

Module

A

Telecommunications

Digitization enables convergence, a process of technological “morphing” in which previously distinct devices lose their sharply-defined boundaries, and blend together.

6

Convergence: Convergence: Is It a Phone Is It a Phone or a Computer?or a Computer?

The everything PC TV Internet set-tops Personal Communication Service (PCS) Internet telephony Internet faxing

Module

A

Telecommunications

WebTV allows you to access the Internet using your television set as a display. Visit their web site for more information.

6

NetworksNetworks

Introducing Computer Networks Network Fundamentals Local Area Networks (LANs) Wide Area Networks (WANs)

Module

B

6

Module

B

Introducing Computer Introducing Computer Networks: Networks: Synergy at WorkSynergy at Work

Networks

What is a computer network? Types of computer networks: LANs & WANs

local area networkmetropolitan area networkwide area network

Networking synergies in a nutshellreducing hardware costsenabling shared applicationsbuilding massive information resourcesconnecting people

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Module

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Introducing Computer Introducing Computer Networks: Networks: Synergy at WorkSynergy at Work

Networks

Computer networks enable users to share software and to create common pools of data.

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Network FundamentalsNetwork Fundamentals

Physical media Switching & routing techniquescircuit switchingpacket switchingwhich is best

Networks

6

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Network FundamentalsNetwork FundamentalsNetworks

A message starts at the "top" of a stack of layers and moves down through the various layers (protocol stack) until it reaches

the "bottom" or physical media.

protocol

layers

stack

Protocolsproprietary

protocolsopen protocolsprotocol suite

Network layersthe protocol stack

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Module

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Local Area Networks Local Area Networks (LANs)(LANs): : Limited Reach, Fast Limited Reach, Fast

ConnectionsConnections

Networks

LANs transform an organization's hardware into what seems to users like one gigantic computer system.

Computer 1Sales & marketing

Keyboard & monitor for server

Computer 3Personnel

Computer 4Server - Daily sales

Laser printer

Computer 2Accounting

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Module

B

Local Area Networks Local Area Networks (LANs)(LANs): : Limited Reach, Fast Limited Reach, Fast

ConnectionsConnections

Networks

Networking hardware: Network Interface Cards (NICs)workstationnode

Networking softwarepeer-to-peer networksclient/server networks

Clients

6

Module

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Local Area Networks Local Area Networks (LANs)(LANs): : Limited Reach, Fast Limited Reach, Fast

ConnectionsConnections

Networks

Mediatwisted paircoaxial cablefiber-optic cableinfraredradio

LAN topologiesbus (daisy chain)starring

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Module

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Local Area Networks Local Area Networks (LANs)(LANs): : Limited Reach, Fast Limited Reach, Fast

ConnectionsConnections

Networks

Most networks use a bus, star, or ring topology.

6

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LAN TechnologiesLAN TechnologiesNetworks

Like to learn more about the Ethernet? Check out Charles Spurgeon’s Ethernet Web Site which covers all the Ethernet

technologies used today and includes a practical guide for do-it-yourselfers.

By far the most popular LAN standard is

Ethernet

By far the most popular LAN standard is

Ethernet

Like to know the latest news about LANs? Check out LAN Times, the premiere LAN trade journal

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LAN ProtocalsLAN ProtocalsNetworks

AppleTalk IPX/SPX NetBEUI TCP/IP

Like AppleTalk, TCP/IP can be used with a variety of lower-level protocols, such as Ethernet. A LAN that uses TCP/IP is called an intranet, a term that suggests that it’s an Internet designed for internal use within an organization.

6

Module

B

Wide Area Networks Wide Area Networks (WANs)(WANs): : Long-Haul CarriersLong-Haul Carriers

Networks

How WANs workPoint of Presence (POP)backbones

WANs are like long-distance telephone systems

The Internet is a WAN of massive proportions. Backbone provider UUNET offers local access from

more than 1,000 locations worldwide.

6

Module

B

Wide Area Networks Wide Area Networks (WANs)(WANs): : Long-Haul CarriersLong-Haul Carriers

Networks

How WANs are organizedpublic data network (PDN)virtual private network (VPN)

WAN protocalsoldest is X.25

WAN ApplicationsLAN-LAN connectionstransaction acquisitionelectronic data interchange (EDI)

To explore cutting-edge WAN technologies such as SDMS and ATM, a good place to start is Pacific Bell’s FasTrak

Data and Video Services page