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OverviewIn this chapter, you will learn to
Explain how the Internet works
Connect to the Internet
Use Internet software tools
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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
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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
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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
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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
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Connection ConceptsConnecting to an ISP requires
Hardware for connectivityModem and working phone lineDSL or cable modem
Software (protocols)Governs the connection and data flow
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Ways of ConnectingDial-up
AnalogISDN
DedicatedDSLCableLAN
Wireless
Satellite
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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
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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
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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
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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
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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
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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
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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
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Dial-up NetworkingCompleting the setup of a dial-up Internet
connection
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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
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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
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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
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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
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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
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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
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Windows XP FirewallBuilt into Windows XP
Originally named Internet Connection Firewall (ICF)
Changed to Windows Firewall in SP2
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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
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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
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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
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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
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E-mail• Configuring e-mail
– Can use name or IP
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NewsgroupsUse a newsreader program to access
newsgroupsOutlook Express most common newsreader
(free)
News servers run Network News Transfer Protocol (NNTP)
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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
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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
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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
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Terminal EmulationRemote Desktop
Microsoft’s implementation
Free and built into system
Remote AssistanceEnd user requests helpHelper can take control
of desktop If permission granted
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Beyond A+ Online gaming
World of Warcraft (WOW)
ChatInternet
Relay Chat (IRC)
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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