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Extended Learning Module EExtended Learning Module E NETWORK BASICS

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STUDENT LEARNING OUTCOMES

1. Identify and describe the four basic concepts on which networks are built and describe what is needed to set up a small peer-to-peer network at home.

2. Describe the components used to build large business networks and define and compare local area networks (LANs), wide area networks (WANs), and metropolitan area networks (MANs).

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STUDENT LEARNING OUTCOMES

3. Compare and contrast the various Internet connection possibilities.

4. Compare and contrast the types of communications media.

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STUDENT LEARNING OUTCOMES

5. State the four principles of computer security and describe how different network security devices reflect those principles.

6. Describe client/server business networks from a business and physical point of view.

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INTRODUCTION

Computer network – two or more computers connected so that they can communicate with each other and share information, software, peripheral devices, and/or processing power

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INTRODUCTION

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Basic Principles of Networks

Four main principles1. Each computer must have a network interface to

provide a doorway for information2. The network usually has at least one connecting

device3. The network must have communications media to

transport information

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Basic Principles of Networks

4. Each computer must have software to move information in and out of the computer

These four principles apply to all networks, large and small

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HOME NETWORKS

A typical home network setup has1. An Ethernet network card in each computer or a

wireless card in each laptop2. Network cables to transmit signals, or no cables for

wireless3. A DSL or cable modem connection and a

broadband/home router

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Network Cards

Network interface card (NIC) – an expansion card or PC card that connects your computer to a networkEthernet card – the most common type of network

interface cardBuilt into the motherboards of many new computers –

looks like a telephone jack, but wider

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Wired Transmission Media

Cat 5 (Category 5) cable – better-constructed version of phone twisted-pair cable

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Wireless Transmission Media

Wireless Access Point (WAP) – device that allows a computer to use radio waves to access a network

Connects to hub or switch with a cable like a wired computer

May be built into broadband router and not require separate cabling

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Home Internet Service

Broadband router or home router – a device to connect computers together to share DSL or cable Internet service in a home or small officeOne port to plug into DSL or cable connection to

connect to the InternetUsually several ports to build a network for home

computers or printers and share Internet connection

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Network Software

Makes each computer's hardware workCan use WindowsTurn on filesharing to make files available to other

computers on the network

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NETWORK COMPONENTS

Hub – a device that connects computers into a network and repeats all transmissions to every connected computerOnly one computer can transmit at a timeAll computers see every messageCan have collisions when two computers try to

transmit at the same time

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NETWORK COMPONENTS

Switch – a device that connects computers and repeats transmissions only to intended recipientMultiple conversations can occur simultaneously

between different sets of computersOnly recipient computer sees each messageComputers can still broadcast messages to all other

computers on the network

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NETWORK COMPONENTS

Router – a device that connects subnetworks (subnets) of a larger networkCan connect different buildings at same or different

locationsPasses transmissions from one network to anotherMay pass through multiple routers on the way from

source to destination

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NETWORK COMPONENTS

More on routersHome/broadband routers often have built-in switches

or hubsCorporate routers generally require separate switches

or hubsRouters must be configured with information about the

networks they connect

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NETWORKS BY DISTANCE

Large networks can be classified by the proximity of the area(s) they serve:Local Area Network (LAN) – network that serves a

building or buildings in a contiguous area

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NETWORKS BY DISTANCE

More networks by distanceWide Area Network (WAN) – a set of connected

networks serving areas not immediately contiguousMetropolitan Area Network (MAN) – a set of

connected networks within the same city or metropolitan area but not in immediate proximity to each other

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THE INTERNET

A vast network of computers that connects people all over the world

Computers pass messages through routers to their ultimate destinations

Each router determines whether it has a direct path to the recipient or whether to send the message on to another router

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Bandwidth

The amount of information that can be transferred in a given amount of time

Usually expressed as bits per second (bps) Higher bandwidths expressed as

kilobits per second (Kbps) – thousands of bits per second

megabits per second (Mbps) – millions of bits per second

gigabits per second (Gbps) – billions of bits per second

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Internet Connection Types

Phone line and dialup modemPhone line and DSL modemCable TV line and cable modemSatellite modemDedicated high-speed business lines

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Broadband Internet Connection

Broadband – high-capacity telecommunications line capable of providing high-speed Internet service

All Internet access methods on the previous slide are broadband except the dialup modem

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Dialup Connection

Modem – connects a computer to a phone line to access another computer or network

Modulates outgoing signal from digital to analog formDemodulates incoming signal from analog to digital

form

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Digital Subscriber Line (DSL)

Digital Subscriber Line (DSL) – high-speed Internet connection using phone lines, which allows you to use your phone for voice communications at the same time

Runs at a higher frequency than voice conversations, so not supported on some older phone lines

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Cable Modem

Cable modem – uses your TV cable to deliver an Internet connection

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Satellite Modem

Satellite modem – delivers Internet access from satellite dish

Satellite TV and modem may share same dish or may be separate

Connects to computer or broadband router like cable modem

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T1 and DS3 Business Lines

T1 and DS3 developed by phone companies to carry many long-distance voice conversations

T1 runs up to about 1.5 MbpsDS3 runs up to about 45 MbpsCan carry both voice and network over the same

lines

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Frame Relay and ATM Business Services

Frame Relay and ATM are used to connect many branch offices to the main office

Use virtual circuits to simulate having a line from every office to every other office

Virtual Circuits

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Comparison of Connection Types

Telephone modem+ Inexpensive and available anywhere there's a phone

line- Slow, and ties up the line for voice calls too

DSL+ Higher-speed connection, doesn't tie up the phone

line for voice calls, and can be left on all the time- Not available in all areas or on all lines

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Comparison of Connection Types

Cable modem+ Higher-speed connection, doesn't use the phone

line at all, and always-on- Connection shared with the neighborhood, so speed

may varySatellite modem

+ Available in remote locations where DSL and cable aren't

- High cost

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Comparison of Connection Types

T1 and DS3+ High-speed to very-high-speed connections, can

transmit both voice and data- High cost that may be mileage-dependent

Frame relay and ATM+ Use virtual circuits to simulate more inter-office

connections than are physically present- High cost normally affordable only by mid- to large-

scale enterprises

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Voice Over IP

Voice over IP – allows you to send voice communications over the Internet and avoid long-distance toll charges

No long-distance calling cost

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NETWORK COMMUNICATIONS MEDIA

Communications media – the paths in a network over which information travels

Wired communications media – transmit information over a closed, connected path

Wireless communications media – transmit information through the air

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Wired Communications Media

Twisted-pair cable – a bundle of copper wires for transmitting voice or data

Cat 5 and Cat 5e are common for modern networksCoaxial cable (coax) – one central wire surrounded

by insulation, a metallic shield, and a covering of insulation

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Wired Communications Media

Optical fiber – uses a very thin glass or plastic fiber through which pulses of light travel

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Wireless Communications Media

Infrared – uses red light to send and receive information

Bluetooth – a standard for transmitting information in the form of short-range radio waves over distances of up to 30 feet and is used for purposes such as wirelessly connecting a cell phone or PDA to a computer

Microwave – a type of radio transmissionRepeater – receives a radio signal, strengthens it, and

sends it on

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Wireless Communications Media

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Wireless Communications Media

Communications Satellite – microwave repeater in space

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NETWORK SECURITY

The four principles of network security are:1. Confidentiality2. Authenticity3. Integrity4. Availability

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NETWORK SECURITY

Confidentiality – information can be obtained only by those authorized to access itBank statements, credit reports, employee evaluationsThreatened by capture of network transmissions and

easily-guessed passwords

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NETWORK SECURITY

Authenticity – information really comes from the source it claims to come fromMilitary orders, medical diagnoses, stockbroker

directionsThreatened by fraudulent e-mails and misspellings of

popular Web site names

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NETWORK SECURITY

Integrity – information has not been alteredBank balance, corporate Web site, prescriptions,

credit card chargesThreatened by forged network transmissions and

faulty server software

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NETWORK SECURITY

Availability – a service or resource is available when it's supposed to beMail-order Web site, corporate e-mail serverThreatened by network failures, faulty server software,

and high volumes of malicious network traffic

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Firewalls & Intrusion Detection Systems

Firewall – protects a computer from intrudersIntrusion detection system (IDS) – watches for

and reports intrusion attempts Intrusion prevention system (IPS) – type of IDS

that also takes action against intrusion attempts

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Encryption

Encryption – scrambles data so you can't read it without having the decryption key

Virtual Private Network (VPN) – encrypts all network transmissions between two endpoints to protect confidentiality and integrity of data

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Firewalls & Intrusion Detection Systems

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Malware

Malware – software designed to harm your computer or security

1. Virus – software written with malicious intent to cause annoyance or damage

2. Worm – spreads itself from computer to computer via e-mail and other network traffic

3. Spyware – collects information about you and reports it to someone else without your permission

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CLIENT/SERVER SOFTWARE MODEL

Client/server network – a network in which one or more computers are servers and provide services to the other computers, called clients

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Client/Server: A Business View

Client/server networks differ according to1. Where the processing for the presentation of

information occurs2. Where the processing of logic or business rules

occurs3. Where the data management component (DBMS)

and information (database) are located

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Client/Server: Model 5

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Five Models of Client/Server

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Five Models of Client/Server

1. Distributed Presentation The server handles almost all functions, including a

major portion of the presentation2. Remote Presentation

The client handles all presentation functions 3. Distributed Logic

The server handles all data management, the client handles all presentation formatting, and the logic processing is shared

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Five Models of Client/Server

4. Remote Data Management The server handles data management only, and the

client processes business rules and formats the presentation of results

5. Distributed Data Management The client handles all presentation formatting and

business rule processing, and both the server and client share data management duties