computer concepts – illustrated introductory, seventh edition unit e: networks and the internet

Computer Concepts – Illustrated Computer Concepts – Illustrated Introductory, Seventh EditionIntroductory, Seventh Edition

UNIT E:

Networks and the Internet

ObjectivesObjectives

Introduce networks

Classify networks

Explore network hardware

Explore data transport

Compare wireless and wired technology

Install a LAN

Computer Concepts – Illustrated Introductory, Seventh Edition

ObjectivesObjectives

Share network resources

Introduce Internet technology

Explore IP addresses and domain names

Connect to the Internet with wires

Connect to the Internet without wires

Objectives

Talking points: Why pay for Internet access if you can get it for free?

Introducing NetworksIntroducing Networks

Communications network -combination of hardware, software, and connecting links that transport data

Allow users to share resources – hardware, software, and data

EthernetSignificant network idea conceived

by Bob Metcalfe in 1976Transfers data between computersKey element in nearly every

computer network• Including Internet

Computer is on network if: computer can access other computers

or share hardware with other computers

Networks in home Access surveillance and monitoring

devices Control media devices Share hardware and software

Sharing networked hardware Reduce costs Expand access

Sharing networked software Reduce costs Facilitate data sharing Enable collaboration

Disadvantages of network connection Vulnerability to unauthorized access Susceptibility to malicious code

Most computer owners believe that advantages far outweigh disadvantages

Network is like spider web with many interconnecting points Node - each connection point

• Network nodes typically contain computers, networked peripherals, or network devices

Server Computer connected to network that

distributes resources to network users

Network connects computers and peripherals

Classifying NetworksClassifying Networks

Networks - classified according to size and geographic structure PAN (personal area network) LAN (local area network) NAN (neighborhood area network) MAN (metropolitan area network) WAN (wide area network)

Networks Technologies

Client / server network Must have at least one server and one

or more clients Network computers can serve as clients

or servers

Server Computer that provides services to other

computers the network (clients)

Application server Runs application software for network

workstations

File server Stores files and supplies them to workstations

on request

Print server Handles jobs sent to network printers

Workstation Network client, usually personal

computer

Peer-to-peer structure Does not have a server Workstations serve as both clients and

servers

Exploring Network HardwareExploring Network Hardware

Network device Any electronic device that broadcasts

network data, boosts signals, or routes data to destination

Modems, network interface cards, hubs, switches, routers, gateways, bridges, repeaters

Modem Converts digital signals into signals that

can travel over network

Network interface card (NIC) Network circuitry needed to connect to

network

Ethernet card (Ethernet adapter) NIC designed to support Ethernet

protocolsComputer Concepts – Illustrated Introductory, Seventh Edition

If computer does not have Ethernet adapter,can purchased and installed

USB and PC Ethernet adapters plug into ports on outside of system unit

Network hub Links two or more nodes of wired network

Network switch Sends data only to network devices specified

as destination

Network router Transmits data from one network to another Used to connect LANs and WANs

Network Router

Special hardware for wireless networks Transceiver

• Used to send and receive wireless data

MIMO (multiple-input multiple-output) technology

Networked peripheralAny device with built-in network

circuitryCan connect directly to network

Network attached storage (NAS)Storage device that directly

connects to network

Exploring Data TransportExploring Data Transport

Communications channel (network link) - physical path or frequency for signal transmission Used for transporting data

Wired network Data travels from one device to another

over cables

Wireless network Data travels through air, no need for

cables

Types of cables Twisted pair Shielded twisted pair (STP) Coaxial (coax) Fiber-optic

Buying cable - choose Category 5 (Cat 5) or Category 6 (Cat 6) Rating indicates capacity Higher number, higher capacity

Cables can be purchased in variety of lengths

Ethernet network cables terminated at each end with RJ45 connector

Bandwidth Transmission capacity of communications

channel• High-bandwidth systems include cable and

DSL (broadband)• Systems with less capacity include dial-up,

referred (narrowband)

Other cables can be used to transport data over wired network USB, serial, parallel, SCSI, and FireWire

Wireless networks transport data via RF (radio frequency) signals Microwaves Infrared lights

Comparing Wireless andComparing Wireless andWired TechnologyWired Technology

Wired networks Fast, secure, reliable, simple to

configure

Wireless Provide mobility No unsightly wires or cables to tangle No need to run wires through walls,

ceilings, floors

Wired network is best choice if you need speed

Wired networks more secure than wireless networks Wireless signals pass through air and

can be intercepted more easily

Range limits Wired network - defined by longest

cable in configuration Wireless network - depends on type of

signal, transmitter strength, and physical environment

Signal strength of wireless

network

Prices have equalized between wired and wireless networks May need some additional equipment

for wireless• Wi-Fi card• Wireless access point

or router

Installing a LANInstalling a LAN

Place router in central location,plug into surge protected outlet

Run cables from router toEthernet adapter in each workstation

Run cable from Internet deviceand router’s WAN port

Turn on devices, computershould recognize andestablish connection

Before using network, adjust router configuration settings

Other ways to set up wired network HomePNA network uses telephone wiring in home Power-line network uses existing electrical wiring

Power-line networks form infrastructure of LAN using existing electrical wiring Special NIC to connect computer to standard

electrical outlet

Sharing Network ResourcesSharing Network Resources

Wireless and wired devices can be connected to same network Most wireless routers include ports for

Ethernet cables and WAN port for cable to Internet device

Access network by clicking workgroup name May also have to enter password and

user ID

SSID (service set identifier) Helps log into correct network in places

where networks may overlap

To add workstations Turn on computer with wireless

capabilities Choose correct network Enter network key or passphrase

Workstation owners can specify whether files and locally attached printers can be accessed from other workstations on network

File Sharing

Three ways to connect printer to network using Windows Control Panel Connect it to one workstation in network Network print server Connect printer directly to hub or router

Introducing Internet TechnologyIntroducing Internet Technology

Internet backbone Consists of high-speed fiber-optic cables

connecting high-capacity routers that direct network traffic

Provide main high-speed routes for data traffic

Network service providers (NSP) maintain backbone links and routers

NSP equipment and links are tied together by network access points (NAPs)

Connecting computer to Internet

ISP equipment offers variety of services e-mail, chat groups, IM capabilities, music file sharing,

FTP, and more

Upstream speed Rate of data transmitted from computer

to Internet

Downstream speed Rate of data arriving at computer

Internet uses variety of communications protocolsSupport basic data transport and

services• TCP

– Breaks message or file into packets

• IP– Addresses packets so they can be routed

to destinations

Main Protocols used on Internet

PING (Packet Internet Groper)Sends signal to specific Internet

addressWaits for replyReports elapsed time between

sending and receiving signal

TracerouteRecords packet’s path from your

computer to destinationComputer Concepts – Illustrated Introductory, Seventh Edition

Connection optionsFixed Internet access - links to ISP

from stationary pointPortable Internet access - allows

easy movement of access deviceMobile Internet access – allows

Internet use on the go

Exploring IP Addresses and Exploring IP Addresses and Domain NamesDomain Names

IP address - Series of numbers 204.127.129.001 Each section called ‘octet’ Each address requires 32 bits Four sections create classes of IP addresses

• Based on size, type of network, other functions

ICANN (Internet Corporation for Assigned Names and Numbers)• Coordinates allocation of IP addresses, and

IP addresses - assigned by ISPs or network or system managers

IP addresses can also be obtained through DHCP (Dynamic Host Configuration Protocol)

Dynamic IP addresses Temporary address Generally assigned to computers running

client software for accessing Web, email, listening to Internet radio, chat groups

Static IP address Permanent address Assigned to ISPs, Web sites, Web hosting

services, email servers

Domain name Corresponds to unique IP address

entered into database called Domain Name System

Domain name server – any computer that hosts this database

Connecting to the InternetConnecting to the Internetwith Wireswith Wires

Dial-up connection

POTS (plain old telephone service) is used to transfer data

Voiceband modem Converts digital signals from computer

into analog signals for telephone lines

ISDN (Integrated Services Digital Network)Fixed Internet connection moves data

over ordinary telephone linesUse telephone wall jack as fixed point

of connectionConnect computer to ISDN terminal

adapter which sends digital signals

DSL (digital subscriber line) High-speed, digital, always-on Internet access Uses standard phone lines to transport data Requires modem and filters

Dedicated line T1, T3, and T4 services - high-capacity

dedicated lines can be leased from telephone company

Not used by other customers

Cable connection Provides always-on broadband Internet

access over same infrastructure that offers cable television services

Bandwidth is divided to offer both television and Internet access

Connecting to Internet via cable TV

Connecting to the InternetConnecting to the Internetwithout Wireswithout Wires

Satellite Internet service Means of distributing always-on, high-

speed, asymmetric Internet access Broadcasting signals to and from

personal satellite dish

Fixed wireless Internet service (wireless broadband) Internet access to homes and businesses

by broadcasting data signals over areas large enough to cover most cities and outlying areas

WiMAX (Worldwide Interoperability for Microwave Access) – well-known fixed wireless standard

Public Wi-Fi network Wireless LAN that provides open access

to public In many public places such as

bookstores, coffee shops, airports, hotels, and restaurants

Wi-Fi hotspot Range of Wi-Fi network’s coverage

Mobile WiMAX Designed to offer Internet access with

seamless handoff from coverage area of one tower to another

Portable satellite Internet service - available for those who need access when traveling in remote locations

WAP (Wireless Access Protocol) Communications protocol providing

wireless Internet access from handheld devices

Mobile broadband Allows access to full

spectrum of Internet via handheld device

Requires fast connection, data service subscription, and mobile broadband equipment

Talking Points:Talking Points:Why pay for Internet access if you can get it for free?Why pay for Internet access if you can get it for free?

Free wireless LANs (WLAN) Found in airports, hotels, coffee shops Sometimes offered by rogue WLAN

operators who buy service, then distribute connections over wireless LANs to friends, neighbors, and anyone who passes by

But is this free access always legal?

Talking Points:Talking Points:Why pay for Internet access if you can get it for free?Why pay for Internet access if you can get it for free?

Problems include Piggyback use Data security

Providers feel every person using free Wi-Fi is one fewer customer

Wisdom of unregulated network availability is questioned by resulting ethical, security, and privacy issues

computer concepts – illustrated introductory, seventh edition unit e: networks and the internet

editioncomputer concepts

softwarecomputer concepts

lancomputer concepts

datacomputer concepts

serverscomputer concepts

disadvantagescomputer

wirescomputer concepts

network userscomputer

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