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The Internet

The Internet. Chapter 22. Overview. In this chapter, you will learn to Explain how the Internet works Connect to the Internet Use Internet software tools. Internet. Historical/Conceptual. How the Internet Works. Internet Tiers. Tier 1 (main tier) Nine companies

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The Internet

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  1. The Internet Chapter 22

  2. Overview • In this chapter, you will learn to • Explain how the Internet works • Connect to the Internet • Use Internet software tools

  3. Internet Historical/Conceptual How the Internet Works

  4. 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

  5. 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

  6. 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

  7. 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

  8. Connection Concepts • 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

  9. Essentials CompTIA A+Essentials Getting the Right Sound Card Connecting to the Internet

  10. Ways of Connecting • Dial-up • Analog • ISDN • Dedicated • DSL • Cable • LAN • Wireless • Satellite

  11. 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

  12. 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 Modems

  13. UARTS on Modems

  14. Baud Rate • 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

  15. Communication Standards • 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

  16. 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 Flow Control (Handshaking) • 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

  17. 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

  18. 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 connectionand use the wizard

  19. Dial-up Networking • Completing the setup of a dial-up Internet connection

  20. 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

  21. 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

  22. 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

  23. 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

  24. 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

  25. 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

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

  27. Internet Software Tools

  28. 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

  29. 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

  30. 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

  31. 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

  32. E-mail • Configuring e-mail • Can use name or IP

  33. Newsgroups • Use a newsreader program to access newsgroups • Outlook Express most common newsreader (free) • News servers run Network News Transfer Protocol (NNTP)

  34. 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

  35. 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

  36. 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

  37. 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 Terminal Emulation

  38. Beyond A+ • Online gaming • World of Warcraft (WOW) • Chat • Internet Relay Chat (IRC)

  39. 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

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