© 2007 The McGraw-Hill Companies, Inc. All rights reserved The Internet Chapter 22.

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

The InternetChapter 22


Overview

• In 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

InternetInternet


Internet Tiers

• Tier 1 (main tier)– Nine companies – Own long-distance, high-speed fiber optic networks

called backbones– Interconnect at network access points (NAPs) in

major cities


Internet Tiers

• Tier 2– Smaller regional networks– Larger ISPs that provide Internet access are often

Tier 2 providers

• Tier 3– Even more regional networks

• Built-in redundancy– Decentralized– Can easily adapt to

failures on network


TCP/IP: Language of the Internet

• TCP/IP is the common language of the Internet– Suite of protocols

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

the World Wide Web

• An Internet browser uses HTTP– Internet Explorer– Mozilla Firefox


Internet Service Providers

• Internet service providers (ISPs) gain access to Internet through backbone– Leased from Tier 1 and Tier2 providers

• Users gain access to the Internet thru ISPs


• Connecting to an ISP requires– Hardware for connectivity

• Modem and working phone line• DSL or cable modem

– Software (protocols)• Governs the connection and data flow

Connection Concepts


CompTIA A+Essentials

Essentials

Getting the Right Sound Card

Connecting to the Internet


Ways of Connecting

• Dial-up– Analog– ISDN

• Dedicated– DSL– Cable– LAN

• Wireless

• Satellite


Dial-up Requires a Modem

• The term modem is an abbreviation for modulator/demodulator– Enables computers to communicate with each

other via standard telephone lines

– Converts analog signals into digital signals

– Converts digital signalsinto analog signals


Modems

• A 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


UARTS on Modems


• Baud rate is the basic cycle of time that a modem uses as its carrier frequency– Maximum 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 baud– 14 bits × 2400 baud = speed of 33.6 Kbps

Baud Rate


• Modern 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

Communication Standards


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


Modem Connections

• Modems connect to the PC in one of two ways– Internal modems connect to a

PCI or PCI Express expansion slot

– External modems connect through a serial port or USB port


Dial-up Networking

• Dial-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 applet

• Select Set up or change your Internet connection and use the wizard


Dial-up Networking

• Completing the setup of a dial-up Internet connection


Dial-up Networking

• Uses PPP protocol– Point-to-Point protocol (PPP)– Streaming protocol developed especially for dial-up

Internet access

• Most dial-up errors are user errors– Turn the volume up and verify the connection– Listen for a dial tone– Listen for “modem talk” instead of a person

answering the phone


ISDN

• Integrated 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 setup– Two B (total of 128 Kbps) and one D channel


DSL

• Digital 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


Cable

• Cable– Uses cable TV connections

• Connect the RG-6 or RG-59 coaxial cable to a cable modem• Connect modem to a NIC in the PC with UTP cable

– Very fast speeds—as fast as DSL or faster– Bandwidth is shared with other users, which can

affect performance


Other Internet Connections

• LANs– Most companies connect their network to the Internet

through an ISP– Users connect through the LAN

• Wireless– Wireless connections require access via wired network– If wired network has access, wireless devices can use this

wired network via a WAP

• Satellite– Uploads previously done through modem– Initial connections still must be made through a modem


Internet Connection Sharing

• Internet connection sharing (ICS)– Allows one computer to share single Internet

connection with multiple devices– Available since Windows 98 SE– Requires a LAN between

the devices first


Windows XP Firewall

• Built into Windows XP– Originally named Internet Connection Firewall (ICF)– Changed to Windows Firewall in SP2


Internet Software Tools


World Wide Web

• The World Wide Web (WWW) provides a graphical face for the Internet– Web servers house Web sites– Web browsers access the files on Web servers

• Web browsers are highly configurable– A proxy server enables multiple connections to the

Internet to go through one protected PC• Similar to ICS, but more sophisticated


World Wide Web

• Security and scripts– Active programs and scripts

such as Java and Active Server Pages

• Can be useful and powerful• Can be malicious

– Internet Explorer has configurable options

• Tools | Internet Options | Security tab lets you set security levels


HTTP vs. HTTPS

• HTTP provides no encryption

• HTTP over Secure Sockets Layer (HTTPS)– Provides encryption– Use when submitting personal information such as

credit card numbers, phone numbers, etc.– Verify HTTPS is being used two ways

• Lock icon • HTTPS appears in address bar


E-mail

• Two most popular e-mail programs– Microsoft Outlook Express– Mozilla Thunderbird

• E-mail protocols– Post Office Protocol version 3 (POP3)

• Used for receiving e-mail

– Internet Message Access Protocol (IMAP)• Used for receiving mail, but with more features than POP3

– Simple Mail Transfer Protocol (SMTP)• Used for sending e-mail


E-mail

• Configuring e-mail– Can use name or IP


Newsgroups

• Use a newsreader program to access newsgroups

– Outlook Express most common newsreader (free)

– News servers run Network News Transfer Protocol (NNTP)


File Transfer Protocol

• File 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


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 protocols• Not a single protocol

– Vendors• Skype• Vonage


Terminal Emulation

• Allows access to other computers as if you were there

• University of Cambridge’s VNC– Free and totally cross-platform– Can run and control

Windows from a Macintosh system


Terminal Emulation

• Remote Desktop – Microsoft’s

implementation– Free and built into

system

• Remote Assistance– End user requests help– Helper can take control

of desktop • If permission granted


Beyond A+

• Online gaming– World of Warcraft (WOW)

• Chat– Internet

Relay Chat (IRC)


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 Internet

• Napster and Kazaa are file sharing programs

– Music industry trying to stop file sharing

– BitTorrent protocol to counter music industry

• Also used for Linux distributions

• µTorrent is one program using BitTorrent protocol

© 2007 The McGraw-Hill Companies, Inc. All rights reserved The Internet Chapter 22.

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Transcript of © 2007 The McGraw-Hill Companies, Inc. All rights reserved The Internet Chapter 22.