Chapter 8


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Chapter 8

  1. 1. Chapter 8 Communications and Networks
  2. 2. Chapter 8 Objectives Discuss the components required for successful communications Describe uses of computer communications Differentiate among types of networks Explain the purpose of communications software Describe various types of lines for communications over the telephone network Describe commonly used communications devices Discuss different ways to set up a home network Identify various physical and wireless transmission media Next
  3. 3. Communications <ul><li>What are computer communications ? </li></ul>p. 296 Fig. 8-1 Next
  4. 4. <ul><li>What is needed for successful communications? </li></ul>Communications p. 296 Sending device — initiates instruction to transmit data, instructions, or information Next Communications device — connects the communications channel to the receiving device Receiving device — accepts transmission of data, instructions, or information Communications device — connects the sending device to the communications channel Communications channel — media on which data, instructions, or information travel
  5. 5. Uses of Computer Communications <ul><li>What are some uses of communications technology? </li></ul>p. 298 Web Internet E-Mail Instant Messaging Internet Telephony Newsgroups Chat Rooms Web Folders Fax Machine or Computer Fax/Modem Video Conferencing FTP Next
  6. 6. Uses of Computer Communications Video: A First Look at Yahoo Messenger 8 with Voice Next CLICK TO START
  7. 7. Uses of Computer Communications <ul><li>What are wireless messaging services? </li></ul>p. 298 - 299 Video messaging Next Wireless instant messaging allows wireless mobile devices to exchange messages Text messaging allows users to send and receive short text messages on a phone or PDA Picture messaging allows users to send graphics, pictures, video clips, sound files, and short text messages Click to view Web Link, click Chapter 8, Click Web Link from left navigation, then click Video Messaging below Chapter 8
  8. 8. Uses of Computer Communications <ul><li>What are wireless Internet access points and cybercafés ? </li></ul>p. 300 -301 Fig. 8-4 <ul><ul><li>Wireless Internet access point allows wireless connection to Internet in public location </li></ul></ul><ul><ul><ul><li>3G network </li></ul></ul></ul><ul><ul><li>Cybercafé is coffee house that provides computers with Internet access </li></ul></ul>Next
  9. 9. Uses of Computer Communications <ul><li>What is a global positioning system (GPS) ? </li></ul>p. 301 Fig. 8-5 Step 1. GPS satellites orbit Earth. Every thousandth of a second, each satellite sends a signal that indicates its current position to the GPS receiver. Step 2. A GPS receiver (such as in a car, a wearable device, a smart phone, a handheld device, or a collar) determines its location on Earth by analyzing at least 3 separate satellite signals from the 24 satellites in orbit. Next Click to view Web Link, click Chapter 8, Click Web Link from left navigation, then click GPS below Chapter 8
  10. 10. Uses of Computer Communications <ul><li>What are collaboration and groupware ? </li></ul>p. 302 Fig. 8-6 <ul><ul><ul><li>A document management system provides for storage and management of a company’s documents </li></ul></ul></ul><ul><ul><li>Groupware is software that allows people to share information </li></ul></ul><ul><ul><li>Collaboration is working with other users connected to a server </li></ul></ul>Next
  11. 11. Uses of Computer Communications <ul><li>What are voice mail and web services ? </li></ul>p. 302 <ul><ul><li>Voice mail is voice message converted to digital form </li></ul></ul><ul><ul><li>Web services describe standardized software that enables programmers to create applications that communicate with other remote computers over the Internet or over an internal business network </li></ul></ul>Next
  12. 12. Networks <ul><li>What is a network ? </li></ul>p. 303 - 304 <ul><ul><li>Collection of computers and devices connected via communications devices and transmission media </li></ul></ul>What is a local area network (LAN) ? <ul><ul><li>Network in limited geographical area such as home or office building </li></ul></ul><ul><ul><ul><li>Metropolitan area network (MAN) connects LANs in city or town </li></ul></ul></ul>Next Click to view Web Link, click Chapter 8, Click Web Link from left navigation, then click Wireless Local Area Networks below Chapter 8
  13. 13. Networks <ul><li>What is a wide area network (WAN) ? </li></ul>p. 304 Fig. 8-8 <ul><ul><li>Network that covers large geographic area using many types of media </li></ul></ul><ul><ul><li>Internet is world’s largest WAN </li></ul></ul>Next
  14. 14. Networks <ul><li>What is a client/server network ? </li></ul>p. 305 Fig. 8-9 <ul><ul><li>One or more computers act as server and other computers, or clients , access server </li></ul></ul>Next
  15. 15. Networks <ul><li>What is a peer-to-peer network ? </li></ul>p. 305 Fig. 8-10 <ul><ul><li>Simple network that connects fewer than 10 computers </li></ul></ul><ul><ul><li>Each computer, or peer, has equal capabilities </li></ul></ul>Next
  16. 16. Networks <ul><li>What is Internet peer-to-peer ( P2P )? </li></ul>p. 306 Fig. 8-11 <ul><ul><li>Enables users to connect to each other’s hard disks and exchange files directly </li></ul></ul>Next
  17. 17. Networks <ul><li>What is network topology ? </li></ul><ul><li>Layout of devices in a network </li></ul><ul><ul><ul><li>Popular topologies are bus, ring, and star </li></ul></ul></ul><ul><ul><li>Bus network </li></ul></ul><ul><ul><ul><li>All computers and devices connect to a single central cable, or bus </li></ul></ul></ul>p. 306 Fig. 8-12 Next
  18. 18. Networks <ul><li>What is a ring network ? </li></ul>p. 307 Fig. 8-13 <ul><ul><li>Cable forms closed ring, or loop, with all computers and devices arranged along ring </li></ul></ul><ul><ul><li>Data travels from device to device around entire ring, in one direction </li></ul></ul>Next
  19. 19. Networks <ul><li>What is a star network ? </li></ul>p. 307 Fig. 8-14 <ul><ul><li>All devices connect to a central device (hub or switch) </li></ul></ul><ul><ul><li>All data transferred from one computer to another passes through hub or switch </li></ul></ul>Next
  20. 20. Networks <ul><li>What is an intranet ? </li></ul>p. 307 Next Extranet allows customers or suppliers to access part of company’s intranet Typically includes connection to Internet Makes information accessible to employees Internal network that uses Internet technologies
  21. 21. Networks <ul><li>What are Ethernet and token ring ? </li></ul>p. 308 <ul><li>Ethernet technology allows computers to contend for access to network </li></ul><ul><ul><li>If two computers send data at same time, a collision occurs and computers must send again </li></ul></ul>Token ring technology controls access to network by requiring devices to pass a special signal, called token Next Click to view Web Link, click Chapter 8, Click Web Link from left navigation, then click Ethernet below Chapter 8
  22. 22. Networks <ul><li>What are TCP/IP and 802.11 (Wi-Fi) ? </li></ul>p. 308 - 309 <ul><ul><li>TCP/IP ( T ransmission C ontrol P rotocol/ I nternet P rotocol) technology transmits data by breaking it up into small pieces, or packets </li></ul></ul><ul><ul><ul><li>Commonly used for Internet transmissions </li></ul></ul></ul><ul><ul><li>802.11 is family of standards for wireless LANs </li></ul></ul><ul><ul><ul><li>Also known as Wi-Fi ( wireless fidelity ) </li></ul></ul></ul>Next
  23. 23. Networks <ul><li>What is Bluetooth ? </li></ul>p. 309 <ul><ul><li>Short-range radio waves transmit data between Bluetooth devices </li></ul></ul>Next
  24. 24. Network Communications Standards <ul><li>What are UWB, IrDA , RFID , WiMAX , and Wireless Applications Protocol (WAP) ? </li></ul>p. 309 – 310 IrDA specification allows data to be transferred wirelessly via infrared light waves Wireless Application Protocol (WAP) allow wireless mobile devices to access Internet Radio Frequency Identification (RFID) uses radio signals to communicate with a tag placed in an object Worldwide Interoperability for Microwave Access (WiMAX or 802.16) standard that specifies how wireless devices communicate over the air in a wide area UWB specification allows data to be transferred wirelessly via short-range radio waves Next
  25. 25. Communications Software <ul><li>What is communications software ? </li></ul>p. 310 Next Programs that help users establish connection to Internet, other network, or another computer Programs that help users manage transmission of data, instructions, and information Programs that provide an interface for users to communicate with one another
  26. 26. Communications Over the Telephone Network <ul><li>What is the public switched telephone network (PSTN)? </li></ul>p. 310 Fig. 8-15 <ul><ul><li>Worldwide telephone system that handles voice-oriented telephone calls </li></ul></ul>Next
  27. 27. Communications Over the Telephone Network <ul><li>What is a dial-up line ? </li></ul>p. 311 <ul><ul><li>Temporary connection using one or more analog telephone lines for communications </li></ul></ul><ul><ul><ul><li>Costs no more than making regular call </li></ul></ul></ul><ul><ul><ul><li>Computers at any two locations can establish a connection using modems and telephone network </li></ul></ul></ul>Next
  28. 28. Communications Over the Telephone Network <ul><li>What is a dedicated line ? </li></ul>p. 311 Fig. 8-16 <ul><ul><ul><li>Five types are ISDN line, DSL, FTTB and FTTH, T-carrier line, and ATM </li></ul></ul></ul><ul><ul><li>Always-on connection between two communications devices </li></ul></ul>Next
  29. 29. Communications Devices <ul><li>What is a communications device ? </li></ul>p. 312 – 313 Fig. 8-17 Next Any type of hardware capable of transmitting data, instructions, and information between devices communication over a CATV line communication over a telephone line
  30. 30. Communications Devices <ul><li>What is a dial-up modem ? </li></ul>p. 313 - 314 <ul><ul><li>Converts digital signals to analog signals and vice versa </li></ul></ul><ul><ul><li>Notebook computers often use PC Card modem </li></ul></ul>Next
  31. 31. Communications Devices <ul><li>What are ISDN and DSL modems ? </li></ul>p. 314 Communications devices that send and receive digital ISDN and DSL signals Usually external devices in which one end connects to a telephone line and the other end connects to a port on the system unit Next
  32. 32. Communications Devices <ul><li>What is a cable modem ? </li></ul>p. 314 Fig. 8-18 <ul><ul><li>Sends and receives data over cable television network </li></ul></ul><ul><ul><li>Much faster than dial-up modem or ISDN </li></ul></ul>Next Click to view Web Link, click Chapter 8, Click Web Link from left navigation, then click Cable Modems below Chapter 8
  33. 33. Communications Devices <ul><li>What is a wireless modem ? </li></ul>p. 314 Fig. 8-19 <ul><ul><li>Allows access to the Web wirelessly from a notebook computer, a PDA, a smart phone, or other mobile device </li></ul></ul><ul><ul><li>Typically use the same waves used by cellular telephones </li></ul></ul>Next
  34. 34. Communications Devices <ul><li>What is a network card ? </li></ul>p. 315 Fig. 8-20 <ul><ul><li>Adapter card, PC Card, ExpressCard module, USB network adapter or flash card that enables a computer or device to access a network </li></ul></ul>Next
  35. 35. Communications Devices <ul><li>What is a wireless access point ? </li></ul>p. 315 <ul><ul><li>Central communications device that allows computers and devices to transfer data wirelessly among themselves or to wired network </li></ul></ul>Next
  36. 36. Communications Devices <ul><li>What is a router ? </li></ul>p. 315 Fig. 8-21 <ul><ul><li>Connects computers and transmits data to correct destination on network </li></ul></ul><ul><ul><li>Routers forward data on the Internet using fastest available path </li></ul></ul>Next
  37. 37. Home Networks <ul><li>What is a home network ? </li></ul>p. 316 - 317 Fig. 8-22 <ul><ul><li>Multiple computers connected in home </li></ul></ul><ul><ul><li>Several types of home networks </li></ul></ul><ul><ul><ul><li>Ethernet — connect computers via cable </li></ul></ul></ul><ul><ul><ul><li>Powerline cable — use electrical lines in house </li></ul></ul></ul><ul><ul><ul><li>Phoneline — use telephone lines </li></ul></ul></ul>Next Click to view Web Link, click Chapter 8, Click Web Link from left navigation, then click Home Networks below Chapter 8
  38. 38. Communications Channel <ul><li>What is a channel? </li></ul>p. 317 - 318 <ul><ul><li>Transmission media on which data, instructions, or information travel in communications system </li></ul></ul><ul><ul><li>Bandwidth is amount of data that can travel over a communications channel </li></ul></ul><ul><ul><li>Transmission media are materials capable of carrying one or more signals </li></ul></ul>Next
  39. 39. Communications Channel <ul><li>How is a request sent over the Internet using a communications channel? </li></ul>p. 318 Fig. 8-23 Next
  40. 40. Physical Transmission Media <ul><li>What are twisted-pair cable and coaxial cable ? </li></ul>p. 319 - 320 Figs. 8-24—8-25 <ul><ul><li>Twisted-pair cable is used for telephone systems and network cabling </li></ul></ul><ul><ul><li>Coaxial cable is often used for cable television wiring </li></ul></ul>Next
  41. 41. Physical Transmission Media <ul><li>What is fiber-optic cable ? </li></ul>p. 320 Fig. 8-26 <ul><ul><li>Capable of carrying significantly more data at faster speeds than wire cables </li></ul></ul><ul><ul><li>Less susceptible to interference (noise) and, therefore, more secure </li></ul></ul><ul><ul><li>Smaller size (thinner and lighter) </li></ul></ul>Next
  42. 42. Wireless Transmission Media <ul><li>What is wireless transmission media? </li></ul>p. 320 <ul><ul><li>Used when inconvenient, impractical, or impossible to install cables </li></ul></ul><ul><ul><li>Includes infrared, broadcast radio, cellular radio, microwaves, and communications satellites </li></ul></ul>Next
  43. 43. Wireless Transmission Media <ul><li>What are broadcast radio and cellular radio ? </li></ul>p. 321 <ul><ul><li>Broadcast radio distributes radio signals through the air over long distances </li></ul></ul><ul><ul><li>Cellular radio is form of broadcast radio used for mobile communications </li></ul></ul><ul><ul><ul><li>A cellular telephone is a telephone device that uses high-frequency radio waves to transmit voice and digital data messages </li></ul></ul></ul>Next Click to view Web Link, click Chapter 8, Click Web Link from left navigation, then click Cellular Communications below Chapter 8
  44. 44. Wireless Transmission Media <ul><li>What is a microwave station ? </li></ul>p. 321 <ul><ul><li>Earth-based reflective dish used for microwave communications </li></ul></ul><ul><ul><li>Must transmit in straight line with no obstructions </li></ul></ul>Next
  45. 45. Wireless Transmission Media <ul><li>What is a communications satellite ? </li></ul>p. 321 <ul><ul><li>Space station that receives microwave signals from earth-based station, amplifies signals, and broadcasts signals back over a wide area to any number of earth-based stations </li></ul></ul>Next
  46. 46. Summary of Communications and Networks Chapter 8 Complete Communications terminology and applications How to join computers into a network Various communications devices, media, and procedures
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