OLeary2011Comp PPT Ch09

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Communications andNetworks

Chapter 9

9-1 Copyright 2011 by The McGraw-Hill Companies, Inc. All rights reserved.


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Discuss connectivity, the wireless revolution, andcommunication systems.

Describe physical and wireless communicationschannels.

Discuss connection devices, and services including dial-up, DSL, cable, satellite/air, and cellular.

Describe data transmission factors, including bandwidthsand protocols.

Competencies (Page 1 of 2)



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Competencies (Page 2 of 2)

Discuss networks and key network terminologies.

Describe different types of networks, including local, home,wireless, personal, metropolitan, and wide area networks.

Describe network architectures, including topologies, and

strategies. Describe organization issues related to Internet

technologies and network security.

9-3Copyright 2011 by The McGraw-Hill Companies, Inc. All rights reserved.


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We live in a truly connected society.

Increased connectivity potentially meansincreased productivity

especially in the businessworld.

You will learn more about theconcept of connectivity andthe impact of the wirelessrevolution in this chapter.

Introduction



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Communications

9-5

The process of sharing data, programs, and

information between two or more computers

Copyright 2011 by The McGraw-Hill Companies, Inc. All rights reserved.


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Communications Today

Numerous applications depend on communicationsystemsE-mail, Instant messaging (IM), Internettelephone, and Electronic commerce

Connectivity uses computer networks to link

people and resources Going wireless has been the most dramatic

change



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Communication Systems Four basic elements

Sending and receiving devices

Communication channel

Connection devices

Data transmission specifications



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Channels carry data from one computer to

another

Two categories of communication

channels

Physical connection

Wireless connection

Communication Channels



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Ethernet cable

(Twisted pair cables)

Coaxial cable

Fiber-optic cable

Physical Connections

9-9Return



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Wireless Connections

Radio frequency (RF) Wi-Fi (wireless fidelity)

802.11

Bluetooth

Microwave Line of sight

Satellite

GPS

Infrared Short distances

Line of sight



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Communication ChannelsS

ummary



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Types of signals

Analog

Digital

Connection Device Signals



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Types of modems

Telephone

DSL

Cable

Wireless

Connection Devices

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Transfer Speeds



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D

ial-Up services Leased lines T1 T3 and DS3 have higher capacity

Digital subscriber line (DSL) Uses existing phone lines

One type widely used isADSL Cable

Uses existing TV cable

Provides speeds as fast as DSL at a lower cost

Satellite/air connection services Seven times faster than dial-up

Slower than DSL & cable modem

CellularServices - use 3G cellular network

Connection Services



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Typical User Connection Costs

&S

peeds



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Measurement of the capacity of thechannel

Categories Voice band also known as low bandwidth

Medium band

Broadband

Baseband

Bandwidth



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Set of communication rules

Standard for Internet: TCP/IP(Transmission control protocol/Internet

protocol) Identification

Packetization

Protocols



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A computer network is a communicationsystem

Connects two or more computers

Allows information exchange

Networks



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Computer Networks

Node Client

Server

Directory server

Host Switch

Network interfacecards (NIC)

Network operatingsystem (NOS)

Network administrator



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Local area networks

Home networks

Wireless LAN

Personal Area networks Metropolitan area networks

Wide area networks

Network Types

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LAN



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Arrangement is called topology

Types of network topology

Legacy Star

Bus

Current

Ring Tree

Hybrid

Mesh

Network Architecture



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Star Network

Smaller computerslinked to a central unit

Central unit is called

the network switch

Control is maintainedby routing

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Return



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Bus Network Each device handles its own communication

control

There is no host

Has a common connecting cable called abackbone or bus

All communications travel along this bus

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Return



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Ring Network

Each device isconnected to twoother devices

No central file serveror computer

Useful in adecentralizedenvironment

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Return



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Tree Network

Several computerslinked to a centralnode

Also known as ahierarchical network

Useful in centralizedorganizations


Return


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Combination of differenttopologies

Large organizations havea complex of smallernetworks

Smaller networks use a

variety of configurations Connected together they

form a hybrid

Hybrid Network

9-26 Copyright 2011 by The McGraw-Hill Companies, Inc. All rights reserved.Return


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Newest type of topology

Does not use a specifictype of layout

Requires that each nodehave more than oneconnection to other

nodes Wireless technologies

are frequently used

Mesh Network



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Principal Network

Configurations



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Terminal

Client/Server

Peer-to-peer

Distributed

Network Strategies



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Organizational Networks

Intranets Private network within an organization

Provides information toemployees

Extranets

Private network that connects organizations

Used to allow suppliers and others access



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Network Security

Firewalls

Hardware & software

Protects against external threats

Intrusion detection systems (NIDS)

Virtual private networks (VPN)



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Careers In IT

Network Administrator Manage a companys LAN

andWAN networks

Maintain hardware and

software Diagnose and repairproblems

Candidates usually have abachelors degree incomputer science and

practical experience Annual salary is typically

between $48,500 and$79,000



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Telepresence Lets You Be There

Seeks to create the illusion that you areactually at a remote location

Early implementations mainly focus on anextension of video-conferencing

Someday couldbeyond simplevoice

A Look to the Future



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Define and discuss connectivity, thewireless revolution, and communications.

Identify and describe the various physicaland wireless communication channels.

Identify the standard Internet protocol anddiscuss its essential features.

Open-Ended Questions (1 of 2)



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Discuss past and present networktopologies.

Define and discuss four common networkstrategies.

Discussion Questions (2 of 2)


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