1. Networks allow for sharing of resources like files, printers, and applications between connected computers. This provides benefits like cost savings, centralized management, and increased productivity over standalone computers. 2. Common network topologies include peer-to-peer, client-server, bus, star, and ring. Larger networks often use a hybrid approach to balance reliability, capacity, and costs. 3. Key network components include physical media like cables, wireless cards, and fiber optics. Logical components include servers, clients, switches, and routers that facilitate communication and sharing across the network.

1. Computer NetworkChapter 4

2. “I think there is a world of market for maybe five computers”Thomas J. Watson Chairman IBM, 1943

3. Why Use Networks?NetworkGroup of computers and devicesConnected by transmission mediaStand-alone computerNot connected to other computersUses local software and dataAdvantages of networks over standalone computersDevice sharing by multiple usersSaves money and timeCentral network management

4. Types of NetworksNetwork modelsPeer-to-PeerClient/server

5. Peer-to-Peer NetworkFigure 1-1 Resource sharing on a simple peer-to-peer network

6. Client/Server NetworksFigure 1-2 Resource sharing on a client/server network

7. ComputersPrinterCopierFaxScannerPersonal Digital AssistantsCell PhonesRadiosRFID (Radio Frequency ID)Networks are everywhere

8. IntroductionToday people are often linked by wires or air (wireless) carrying voice and computer signals via the telephone system.

9. Data communications dominate the world.

10. Computer Network: The linkage of computer systems by means of communication lines or channels (e.g., fiber optic, microwave, satellite, telephone line, 802.11)Computer NetworkAt least two computers need to be connectedCopper

11. Fiber Optics

12. Microwaves

13. Infrared

14. SatellitesData CommunicationsData Processing+Telecommunications= Data Communications

15. Data CommunicationElectronic transfer of information from one computer to another.DataTextPicturesGraphicsVideoVoice

16. Network Components (Examples) Introduction1-12LinksInterfacesSwitches/routersEthernet cardLarge routerFibersWireless cardCoaxial CableSwitch

17. Why network?Resource sharing

18. Files, Applications, Printer, Fax

19. Communication Medium

20. Email, Collaboration, videoconferencing

21. E-business

22. Supply-chain, inventory, B2CBusiness Applications of NetworksA network with two clients and one server.

23. Business Applications of Networks (2)The client-server model involves requests and replies.

24. Home Network ApplicationsAccess to remote information

25. Person-to-person communication

26. Interactive entertainment

27. Electronic commerceCommunication Lines/ChannelsFiber opticMicrowaveSatelliteTelephone Line etc.

28. Impact of Data CommunicationsIt enables information to be accessed and transmitted quickly.Automatic Data Collection or Polling (i.e. Chuck E. Cheese) –menu update, get info from POSIt allows the storing of information in a centralized database that may be shared by a few users in a small computer network or by thousands of users in a large computer network.It facilitates centralized management and decentralized operations (e.g., restaurant chain).

29. Impact of Data CommunicationsIt links business processes performed by independent computer systems to improve organizational efficiency and effectivenessIt links a business to its customersCommunication devices, such as cell phones, personal digital assistants, etc.

30. Local Area NetworkLAN is linkage of computers in a specific geographical area (usually within an office or building) such as in hotels, restaurants, or country clubs using transmission medium such as twisted pair wire or coaxial cable.

31. Why Local Area Network (LAN)?Increased processing and transfer requirements in many graphics-intensive applications now require significantly higher transfer rates (data, audio, image, video)Decreased cost of storage space leads to program and file bloat, increased need for transfer capacityWatch this video

32. Basic LAN HardwareComputers/Server(s)ResourcesCablesConnectors (Hubs)Network Interface Cards (Ethernet) ADVANCEDBridgesRouters

34. Full versus half duplexHalf duplex: communication can happen in both directions but one at a time (like walkie-talkie)Full duplex: communication can happen in both directions at the same time (like a phone)

35. ClientIs any network entity that can request resources from the network. Workstations can be clients but not all clients are workstationsFor example, a printer can request resources from the network, it is a client, not a workstation.

36. ServerA computer that provides resources to the clients on the network.Servers are typically powerful computers

37. Switch

38. Hub vs. SwitchHub—sends signals to all computers connectedSwitch– sends signals to intended computer(s)

39. LANs shareFiles (databases)Resources (Printers, fax)Programs (Fidelio, MS Office)Working togetherCommunication

40. WAN (Wide Area Network ) Communications HardwareWAN=Connection of at least two LANsDown-line processor/ MultiplexerFront-end ProcessorPBX(Private Branch Exchange)Watch Video

41. WAN Connection TypesPrivate Lines

42. Frame Relay

43. Dial-Up

44. Satellite

45. Down Line Processor or Multiplexer

46. Front-end Processor

47. PBX Switchboard

48. Shared Lines

49. DSL

50. CableWAN in HospitalityGlobal Reservation SystemCentral Reservation SystemProperty Management System

51. LAMiamiNYCBoston

52. Hotel Marriott MiamiHotel Marriott NYC Dial-up (max 56Kbps)

53. ISDN (128Kbps)

54. DSL (1.5Mbps)

55. Cable (3.5Mbps)Shared Connection

56. Hotel Marriott MiamiHotel Marriott NYCT-1 (1.5Mbps)

57. Frame Relay (1.5Mbps)

58. T-3 (43Mbps)

59. OC3 (155Mbps)

60. ATM (622Mbps)Dedicated Connection

61. Hotel Marriott NYC802.11b (11Mbps)

62. 802.11g (54Mbps)

63. 802.11a (54Mbps)

64. 802.11n (<100Mbps)WLAN -Dedicated / Shared Connection

65. A Small LAN

66. Wireless LANAdvantagesWireless LANs are simple to set up. It literally can take 10 minutes for a simple wireless network to be setup.Wireless LANs are cheap to create.When it is not possible to wire, Wireless LANs come into rescue.DisadvantagesSecurity is the biggest down side of wireless LANs.

68. HP ServerIBM Server

69. Network Hardware: RepeatersExtend the length of transmission media

70. Server TypesFile Server: holds and distributes filesPrint Server: handles printing jobs from clientsProxy Server: performs a function on behalf of other computersApplication Server: hosts a network application (i.e. Marriott’s central reservation system, Marsha)Web Server: handles web pages and other web content (i.e. Marriott.com, Hilton.com, Starwood.com)Mail Server: hosts and delivers electronic mail.Fax Server: sends and receives faxes electronically.Voice over IP Server: Handles calls on Internet Protocol