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Chapter 8 Communications and Networks

Chapter 8 Communications and Networks. Chapter 8 Objectives. Next. Discuss the components required for successful communications. Describe various types of lines for communications over the telephone network. Describe commonly used communications devices.

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Chapter 8 Communications and Networks

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  1. Chapter 8 Communications and Networks

  2. Chapter 8 Objectives Next Discuss the components required for successful communications Describe various types of lines for communications over the telephone network Describe commonly usedcommunications devices Describe uses of computer communications Differentiate among types of networks Discuss different ways to set upa home network Explain the purpose ofcommunications software Identify various physical and wireless transmission media

  3. Communications notebookcomputers Web-enabledPDAs smartphones servers GPS receivers desktopcomputers mainframecomputers set-top boxes Tablet PCs Next • What are computercommunications? • Process in which two or more computers or devices transfer data, instructions, and information p. 282 Fig. 8-1

  4. Communications Sending device — initiates instruction to transmit data, instructions, or information Communications device— connects the sending device to the communications channel Communications channel — media on which data, instructions, or information travel Communications device— connects the communications channel to the receiving device Receiving device — accepts transmission of data, instructions, or information Next • What is needed for successful communications? p. 282

  5. Uses of Computer Communications Next • What are some uses of communications technology? Internet Web E-Mail InstantMessaging Chat Rooms Newsgroups FTP WebFolders VideoConferencing Fax Machine or Computer Fax/Modem p. 285 Fig. 8-3

  6. Uses of Computer Communications Internet telephonyenables you to talk to other people over the Internet Sometimes calledVoice over IP Internet printing allows you to print to network printer from anywhere in the world Next • What are Internet telephony and Internet printing? p. 285

  7. Uses of Computer Communications Next • What are Web services? • Software that enables programmers to create applications that communicate with other remote computers p. 286

  8. Uses of Computer Communications Next • What are collaboration and groupware? • Collaborationis working with other users connected to a server • Microsoft Office 2003allows collaboration • Groupwareis softwarethat allows peopleto shareinformation p. 286 Fig. 8-4

  9. Uses of Computer Communications Click to view Web Link,click Chapter 8, Click Web Linkfrom left navigation, then click Public Internet Access Pointsbelow Chapter 8 Next • What are public Internet access points and cybercafés? • Public Internet access point allows wireless connection to Internet in public location • Cybercafé is coffee house that provides computers with Internet access p. 287 Fig. 8-5

  10. Uses of Computer Communications Click to view video Click to view Web Link,click Chapter 8, Click Web Linkfrom left navigation, then click GPSbelow Chapter 8 Next • What is a global positioning system (GPS)? p. 288 Fig. 8-6

  11. Uses of Computer Communications Next • What are voice mail and wireless messaging services? • Voice mail is voice message converted to digital form • Wireless messaging services include: • Text Messaging • Instant Messaging • Picture Messaging p. 289 Fig. 8-7

  12. Networks Click to view Web Link,click Chapter 8, Click Web Linkfrom left navigation, then click LANsbelow Chapter 8 Next • What is a network? • Collection of computers and devices connected via communications devices and transmissionmedia • What is a local area network (LAN)? • Network in limited geographical area such as home or office building • Metropolitan area network (MAN) connects LANs in city or town p. 289

  13. Networks Next • What is a wide area network (WAN)? • Network that covers large geographic area using many types of media • Internet is world’s largest WAN p. 290 Fig. 8-8

  14. Networks Next • What is a client/server network? • One or more computers act as server and other computers, or clients, access server p. 291 Fig. 8-9

  15. Networks Next • What is a peer-to-peer network? • Simple network that connects fewer than 10 computers • Each computer, or peer, has equal capabilities p. 291 Fig. 8-10

  16. Networks Next • What is Internet peer-to-peer (P2P)? • Enables users to connect to each other’s hard disks and exchange files directly p. 292 Fig. 8-11

  17. Networks Next • What is network topology? • Layout of devices in a network • Popular topologies are bus, ring, and star • Bus network • All computers and devices connect to a central cable, or bus p. 292 Fig. 8-12

  18. Networks Next • What is a ring network? • Cable forms closed ring, or loop, with all computers and devices arranged along ring • Data travels from device to device around entire ring, in one direction p. 293 Fig. 8-13

  19. Networks Next • What is a star network? • All devices connect to a central device, called hub • All data transferred from one computer to another passes through hub p. 293 Fig. 8-14

  20. Networks Click to view Web Link,click Chapter 8, Click Web Link from left navigation, then click Ethernetbelow Chapter 8 Next • What are Ethernet and token ring? • Ethernet technology allows computers to contend for access to network • If two computers send data at same time, a collision occurs and computers must send again Token ring technology controls access to network by requiring devices to pass a special signal, calledtoken p. 294

  21. Networks Next • What are TCP/IP and 802.11? • TCP/IP (Transmission Control Protocol/Internet Protocol) technology transmits data by breaking it up into small pieces, or packets • Commonly used for Internet transmissions • 802.11 is family of standards for wireless LANs p. 294

  22. Networks Next • What is Bluetooth? • Short-range radio waves transmitdata between Bluetooth devices p. 294

  23. Networks Click to view video Next What are IrDA, RFID, and Wireless Applications Protocol (WAP)? Radio Frequency Identification (RFID)uses radio signals to communicatewith a tag placed in an object IrDAspecification allows data to be transferred wirelessly via infrared light waves Wireless Applications Protocol (WAP)allow wireless mobile devices to access Internet p. 294

  24. Networks Extranet allows customers or suppliers to access part of company’s intranet Makes information accessible to employees Typically includes connection to Internet Internal network that uses Internet technologies Next • What is an intranet? p. 295

  25. Communications Software 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 Next • What is communications software? p. 295

  26. Communications Over the Telephone Network Next • What is the public switched telephone network (PSTN)? • Worldwide telephone system that handles voice-oriented telephone calls p. 296 Fig. 8-15

  27. Communications Over the Telephone Network Next • What is a dial-up line? • Temporary connection using telephone line for communications • Costs no more than making regular call • Computers at any two locations can establish a connection using modems and telephone network p. 296

  28. Communications Over the Telephone Network Next • What is a dedicated line? • Always-on connection between two communications devices • Four types are ISDN line, DSL, T-carrier line, and ATM p. 297 Fig. 8-16

  29. Communications Over the Telephone Network Next • What is an ADSL (asymmetric digital subscriber line)? • Popular type of DSL (Digital Subscriber Line) • Faster when receiving data than when sending data • Ideal for Internet access p. 298

  30. Communications Devices ISDN and DSL modems send and receive data from ISDN and DSL lines Common types are dial-up modems, ISDN and DSL modems, cable modems, network cards, wireless access points, and routers Next • What are examples of communications devices? p. 298

  31. Communications Devices Click to view Web Link,click Chapter 8, Click Web Linkfrom left navigation, then click Dial-Up Modems below Chapter 8 Next • What is a dial-up modem? • Converts digital signals to analog signals and vice versa • Notebook computers often use PC Card modem p. 298 Figs. 8-17–8-18

  32. Communications Devices Next • What are ISDN and DSL modems? 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 p. 300

  33. Communications Devices Next • What is a cable modem? • Sends and receives data over cable television network • Much faster than dial-up modem or ISDN • Sometimes called a broadband modem p. 300 Fig. 8-19

  34. Communications Devices Next • What is a network card? • Adapter card, PC Card, or compact flash card that enables computer or device to access network p. 300 Fig. 8-20

  35. Communications Devices Next • What is a wireless access point? • Central communications device that allows computers and devices to transfer data wirelessly among themselves or to wired network p. 301 Fig. 8-21

  36. Communications Devices Click to view animation Next • What is a router? • Connects computers and transmits data to correct destination on network • Routers forward data on Internet using fastest available path p. 301 Fig. 8-22

  37. Home Networks Click to view Web Link,click Chapter 8, Click Web Linkfrom left navigation, then click Home Networks below Chapter 8 Next • What is a home network? • Multiple computers connected in home • Several types of home networks • Ethernet— connect computers via cable • Powerline cable— use electrical lines in house • Phoneline— use telephone lines • HomeRF (radio frequency)— wireless p. 302 Fig. 8-23

  38. Communications Channel Next • What is a channel? • Transmission media on which data travels in communications system Transmission mediaare materials capable of carrying one or more signals Bandwidthis amount of data that can travel over channel p. 303

  39. Communications Channel Next • How is a request sent over the Internet using a communications channel? Step 1.The sending device requests information using either a physical transmission media or a wireless transmission media. Step 2.When the request leaves the ISP, it travels over T1 lines, microwave stations, earth-based stations, and communications satellites until it reaches the Internet backbone. Step 3.The request travels over T3 lines along the Internet backbone. Step 4.The Request travels over T1 lines until it reaches the destination network server. p. 304 Fig. 8-24

  40. Physical Transmission Media Next • What is physical transmission media? • Wire, cable, and other tangible materials used to send communications signals p. 305

  41. Physical Transmission Media Next • What are twisted-pair cable and coaxial cable? • Twisted-pair cable is used for telephone systems and network cabling • Coaxial cable is often used for cable television wiring p. 305 Fig. 8-25—8-26

  42. Physical Transmission Media Next • What is fiber-optic cable? • Capable of carrying significantly more data at faster speeds than wire cables • Less susceptible to interference (noise) and, therefore, more secure • Smaller size (thinner and lighter) p. 306 Fig. 8-27

  43. Wireless Transmission Media Next • What is wireless transmission media? • Used when inconvenient, impractical, or impossible to install cables • Includes infrared, broadcast radio, cellular radio, microwaves, and communications satellites p. 306

  44. Wireless Transmission Media Click to view Web Link,click Chapter 8, Click Web Linkfrom left navigation, then click Cellular Communications below Chapter 8 Next • What are broadcast radio and cellular radio? • Broadcast radio distributes radio signals over long and short distances • Cellular radio is form of broadcast radio used for mobile communications • A cellular telephone is a telephone device that uses high-frequency radio waves to transmit voice and digital data messages p. 306

  45. Wireless Transmission Media Next • What is a microwave station? • Earth-based reflective dish used for microwave communications • Must transmit in straight line with no obstructions p. 307

  46. Wireless Transmission Media Next • What is a communications satellite? • Space station that receives microwave signals from earth-based station, amplifies signals, and broadcasts signals back to any number of earth-based stations p. 307

  47. Summary of Communications and Networks Communications terminology and applications Various communications devices, media, and procedures How to join computers into a network Chapter 8 Complete

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