Chapter 22

The Internet

MELJUN CORTESMELJUN CORTES

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

OverviewIn this chapter, you will learn to

Explain how the Internet works

Connect to the Internet

Use Internet software tools

How the Internet Works

Historical/Conceptual

Internet

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

Internet TiersTier 1 (main tier)

Nine companies Own long-distance, high-speed fiber optic

networks called backbonesInterconnect at network access points (NAPs)

in major cities

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

Internet TiersTier 2

Smaller regional networksLarger ISPs that provide Internet access are

often Tier 2 providers Tier 3

Even more regional networksBuilt-in redundancy

DecentralizedCan easily adapt to

failures on network

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

TCP/IP: Language of the InternetTCP/IP is the common language of

the InternetSuite of protocols

Hypertext Transport Protocol (HTTP) Most common protocol that provides structure

for the World Wide Web

An Internet browser uses HTTPInternet ExplorerMozilla Firefox

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

Internet Service ProvidersInternet service providers (ISPs) gain

access to Internet through backboneLeased from Tier 1 and Tier2 providers

Users gain access to the Internet thru ISPs

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

Connection ConceptsConnecting to an ISP requires

Hardware for connectivityModem and working phone lineDSL or cable modem

Software (protocols)Governs the connection and data flow

CompTIA A+Essentials

Essentials

Getting the Right Sound Card

Connecting to the Internet

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

Ways of ConnectingDial-up

AnalogISDN

DedicatedDSLCableLAN

Wireless

Satellite

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

Dial-up Requires a Modem The term modem is an abbreviation for

modulator/demodulatorEnables computers to communicate with

each other via standard telephone linesConverts analog signals into digital signals Converts digital signals

into analog signals

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

ModemsA modem uses serial communication

Transmits data as a series of individual 1s and 0s

Universal asynchronous receiver/transmitter (UART)Converts serial into

8-bit parallel data

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

UARTS on Modems

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

Baud RateBaud rate is the basic cycle of time that a

modem uses as its carrier frequencyMaximum baud rate of a phone line is 2400

baud

The modem speed is measured in bits per second (bps)Modems can pack multiple bits into a single

baud14 bits × 2400 baud = speed of 33.6 Kbps

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

Communication StandardsModern modem standards are referred to as V

standards Set by the International Telecommunication

Union—Telecommunications Standardization Sector (ITU-T)

Both standards offer download speeds of just under 56 Kbps V.90 upload speeds of up 33.6 Kbps V.92 upload speeds of up to 48 Kbps

Rarely get throughput greater than 48 Kbps

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

Flow Control (Handshaking)

Hardware flow control uses extra wires called ready to send (RTS) and clear to send (CTS)

Called RTS/CTS

When in doubt, use hardware flow control

• PCs handle local flow control using hardware or software

• Software flow control uses special characters to signal the beginning and end of data transmission

– Called XON/XOFF

– Slower than hardware flow control and rarely used today

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

Modem ConnectionsModems connect to the PC in one of

two waysInternal modems connect to a

PCI or PCI Express expansion slot

External modems connect through a serial port or USB port

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

Dial-up NetworkingDial-up networking

Uses information from your ISP The dial-up phone number, username, password, and

other special configuration parameters

Configured in Network and Internet Connections appletSelect Set up or change

your Internet connection and use the wizard

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

Dial-up NetworkingCompleting the setup of a dial-up Internet

connection

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

Dial-up NetworkingUses PPP protocol

Point-to-Point protocol (PPP)Streaming protocol developed especially for

dial-up Internet access

Most dial-up errors are user errorsTurn the volume up and verify the connectionListen for a dial toneListen for “modem talk” instead of a person

answering the phone

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

ISDNIntegrated Services Digital Network (ISDN)

Phone companies have upgraded their network infrastructures to all digital lines (except for the line from your phone to the central office)

ISDN uses channels B (Bearer) used for data and voice at 64 Kbps D (Delta) used for setup and configuration information at 16

Kbps

Basic Rate Interface (BRI)Most common setupTwo B (total of 128 Kbps) and one D channel

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

DSLDigital subscriber line (DSL)

Uses a regular phone line but special equipment at both ends

Much faster than dial-up: Upload: 384 Kbps Download: 2 Mbps or greater

Installation requires a NIC and DSL receiver (often called a DSL modem)

Must be within 18,0000 feetfrom the closest main phoneservice switching center

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

CableCable

Uses cable TV connectionsConnect the RG-6 or RG-59 coaxial cable to a cable

modemConnect modem to a NIC in the PC with UTP cable

Very fast speeds—as fast as DSL or fasterBandwidth is shared with other users, which

can affect performance

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

Other Internet ConnectionsLANs

Most companies connect their network to the Internet through an ISP

Users connect through the LAN

WirelessWireless connections require access via wired networkIf wired network has access, wireless devices can use this

wired network via a WAP

SatelliteUploads previously done through modemInitial connections still must be made through a modem

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

Internet Connection SharingInternet connection sharing (ICS)

Allows one computer to share single Internet connection with multiple devices

Available since Windows 98 SERequires a LAN between

the devices first

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

Windows XP FirewallBuilt into Windows XP

Originally named Internet Connection Firewall (ICF)

Changed to Windows Firewall in SP2

Internet Software Tools

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

World Wide WebThe World Wide Web (WWW) provides a

graphical face for the InternetWeb servers house Web sitesWeb browsers access the files on Web

servers

Web browsers are highly configurableA proxy server enables multiple connections

to the Internet to go through one protected PCSimilar to ICS, but more sophisticated

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

World Wide WebSecurity and scripts

Active programs and scripts such as Java and Active Server PagesCan be useful and powerfulCan be malicious

Internet Explorer has configurable optionsTools | Internet Options |

Security tab lets you set security levels

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

HTTP vs. HTTPSHTTP provides no encryption

HTTP over Secure Sockets Layer (HTTPS)Provides encryptionUse when submitting personal information

such as credit card numbers, phone numbers, etc.

Verify HTTPS is being used two waysLock icon HTTPS appears in address bar

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

E-mailTwo most popular e-mail programs

Microsoft Outlook ExpressMozilla Thunderbird

E-mail protocolsPost Office Protocol version 3 (POP3)

Used for receiving e-mailInternet Message Access Protocol (IMAP)

Used for receiving mail, but with more features than POP3Simple Mail Transfer Protocol (SMTP)

Used for sending e-mail

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

E-mail• Configuring e-mail

– Can use name or IP

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

NewsgroupsUse a newsreader program to access

newsgroupsOutlook Express most common newsreader

(free)

News servers run Network News Transfer Protocol (NNTP)

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

File Transfer ProtocolFile Transfer Protocol (FTP)

Used to share files

Requires an FTP server on one end and an FTP client on the other WS_FTP is a popular client Internet Explorer and

other Web browsers also support FTP

Public FTP servers allow anonymous login User Name: Anonymous Password: e-mail address

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

Voice over IP Voice over IP (VoIP)

Enables voice calls over the network

Works with any type of high-speed connection DSL, cable, satellite, etc.

VoIP is a collection of protocolsNot a single protocol

VendorsSkypeVonage

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

Terminal EmulationAllows access to other computers as if you

were there

University of Cambridge’s VNCFree and totally cross-platformCan run and control

Windows from a Macintosh system

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

Terminal EmulationRemote Desktop

Microsoft’s implementation

Free and built into system

Remote AssistanceEnd user requests helpHelper can take control

of desktop If permission granted

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

Beyond A+ Online gaming

World of Warcraft (WOW)

ChatInternet

Relay Chat (IRC)

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

Beyond A+ File sharing

Allows users to share files with other users Users can access any shared files (such as MP3s) on any

computer anywhere on the InternetNapster and Kazaa are file sharing programs

Music industry trying to stop file sharing

BitTorrent protocol to counter music industryAlso used for Linux

distributionsµTorrent is one program

using BitTorrent protocol

© 2007 The McGraw-Hill Companies, Inc. All rights reserved