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3.1 Network Basic

Computer Network :: Network Basic

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3.1 Network Basic

  1. 1. Chapter Three 3.1 Network Basic 3.1.1 Basic Concept of Network At the end of this topic, students should be able to: Explain the concept of network
  2. 2. What to cover? • Definition of network • Communication device • Transmission media • Advantages and disadvantages of network
  3. 3. What is a network? A network is a worldwide collection of networks that connects millions of businesses, educational institutions and individuals. (Shelly, 2016) Pages 470 - 471 Discovering Computers : Chapter 9
  4. 4. What is a network? A network is basically a wired or wireless network that connects together a group of computing resources such as computers, printers and servers, which are located at different places. (Yew ,Low, 2014) Pages 470 - 471 Discovering Computers : Chapter 9
  5. 5. Discovering Computers : Chapter 9 Pages 460
  6. 6. Communication System Sending device Receiving device Comm. device Communication channel / Transmission media Comm. device
  7. 7. Communications System • A sending device that initiates an instruction to transmit data, instructions, or information. • A communications device that connects the sending device to a communications channel. • A communications channel, or transmission media on which the data, instructions, or information travel. • A communications device that connects the communications channel to a receiving device. • A receiving device that accepts the transmission of data, instructions, or information.
  8. 8. Communication Devices Hardware or equipment which are designed to transfer signals or data from a sender to receiver. Example: Hub, switch, modem, router, repeater, access point, network interface card (NIC).
  9. 9. Transmission Media Transmission media consist of materials or substances capable of carrying one or more signals. (Shelly, 2012) • A communications channel, or transmission media on which the data, instructions, or information travel.
  10. 10. Types of Transmission Media 1. Wired transmission media The transmission of signals or data by means of wire, cable, or other physical connections (transmitter) between a sender and a receiver. Example: Fiber-optic cable, Cable television(coaxial cable), Internet access(broadband media) and telephone networks(twisted-pair cable)
  11. 11. Types of Transmission Media 2. Wireless transmission media The signals or data are transferred between a sender to a receiver by means of radio (electromagnetic) waves. The sender and receiver are not connected by any electrical or optical wires/cables. Example : cellular radio, satellite, broadcast radio, microwaves, Bluetooth, infrared.
  12. 12. Advantages of Using a Network? Facilitating communications Sharing hardware Sharing data and information Sharing software Transferring funds
  13. 13. facilitating communications Using a network, people communicate efficiently and easily via e-mail, instant messaging, chat rooms, blogs, wikis, online social networks, video telephone calls, online meetings, video conferencing, VoIP, wireless messaging services, and groupware. Sharing hardware In a networked environment, each computer on the network can have access to all hardware on the network. sharing data and information In a networked environment, any authorized computer user can access data and information stored on other computers on the network. sharing software Users connected to a network have access to software on the network. transferring funds Called electronic funds transfer (EFT ), it allows users connected to a network to transfer money from one bank account to another via transmission media.
  14. 14. Discovering Computers : Chapter 9• Page 470 • Figure 9-9
  15. 15. • Viruses When computers are connected by a network, the virus can spread itself electronically, at computer speeds. • Network failure If the file server fails then no-one on the network can access any files or folders. This means that nobody can do any work. For an organisation, this would be extremely costly and disruptive. • Slow service As more users log onto the network and request files, send things to be printed and open more software applications, the network can start to slow down. • Cost Every workstation needs a network interface card to enable it to be connected to the network. Other hardware such as hubs, switches and routers are often needed. • Expert support required Networks need constant monitoring to ensure that the performance is maintained and that all of the components are working properly. This requires specialist staff such as network managers and technicians who will spend all of their time ensuring that the network works efficiently whenever you need to use it. These staff add a large cost to running a network, but without them, things would start to fail. Disadvantages of Using a Network?
  16. 16. Chapter Three 3.1 Network Basic 3.1.2 Network Architecture At the end of this topic, students should be able to: Explain types of network architecture
  17. 17. What to cover? Type of network architecture • Peer-to-peer • Client/Server Differentiate between client/server and peer-to-peer networks, and describe how a peer-to-peer network works
  18. 18. Network Architecture • The design of computers, devices, and media on a network is sometimes called the network architecture Discovering Computers : Chapter 9 18Pages 473 – 474 Figures 9-13 – 9-14 Client/server network Peer-to-peer network
  19. 19. Peer-to-Peer • Each computer, called a peer, has equal responsibilities and capabilities , sharing hardware (such as a printer), data and information with other computers. Discovering Computers : Chapter 9 19Page 475 Figure 9-15 Peer-to-peer network
  20. 20. Client-Server One or more computers act as a server, and the other computers on the network request services from the server. Discovering Computers : Chapter 9 20Page 475 Figure 9-15
  21. 21. Client clients are other computers and mobile devices on the network that rely on the server for its resources. Server server, sometimes called a host computer, controls access to the hardware, software, and other resources on the network and provides a centralized storage area for programs, data, and information.
  22. 22. Peer-to-peer versus client-server Num Peer-to-peer Client-server 1. Every user is taking care of his/her own machine so could be difficult to administer the network Centralized control by the server can be more efficient at administering the whole network. 2. Easy to install and configure for the computers in the network. Network professionals are normally needed to manage and maintain the whole network. 3. Cost to install and maintain network is inexpensive. Cost to install and manage the network can be expensive. 4. Each computer has equal responsibilities and capabilities. Only servers have high responsibilities and capabilities.
  23. 23. Chapter Three 3.1 Network Basic 3.1.3 Network Topology At the end of this topic, students should be able to: Explain types of network topology
  24. 24. Networks • A network topology refers to the layout of the nodes (computers and devices) in a communications network Discovering Computers : Chapter 9 24Pages 475 – 477 Figures 9-16 – 9-18 Star network Bus network Ring network
  25. 25. A network topology refers to the layout of the computers and devices in a communications network. It refers to both the physical and logical layout of a network. What Is a Topology?
  26. 26. Physical Topology The arrangement of a cabling is the physical topology. Logical Topology The path that data travels between computers on a network is the logical topology. Layout of Network
  27. 27. Types of network topology. Three commonly used network topologies are: Bus network Star network Ring network
  28. 28. Diagram of different network topologies. Ring Star Bus
  29. 29. Bus Network Topology A bus network consists of a single central cable (backbone), to which all computers and other devices connect. T-Connector Terminator BackboneT-Connector Nodes
  30. 30. Each devices is connected to the single central cable(backbone) through T-Connector. A terminator is required at each end of the bus cable to prevent the signal from bouncing back and forth on the bus cable. T-Connector Terminator Backbone Bus Network Topology
  31. 31. transmit data, instructions, and information as a series of signal. Those signals are sent as electrical pulses that travel along the length of the cable in all directions. Bus Network Topology
  32. 32. When a sending device transmits data, the address of the receiving device is included with the transmission. If the device address does not match the intended address for the data, the device ignores the data. If the data does match the device address, the data is accepted. All devices receive the data but only the receiving device accept them. Bus Network Topology
  33. 33. Advantages: 1. Bus networks are inexpensive and easy to install. So popular on Local Area Network (LAN). 2. Computers and other devices can be attached and detached at any point on the bus without disturbing the rest of the network. 3. Failure of one device usually does not affect the rest of the bus network. Bus Network Topology
  34. 34. Disadvantages: 1. There might be disruption when computer or other devices are added or removed. 2. Because all systems on the network connect to a single cable or backbone, a break in the cable will prevent all systems from accessing the network. 3. It is difficult to identify the problem if the entire network shut down. Bus Network Topology
  35. 35. Star Network Topology All the computers and other devices on the network connect to a central device, thus forming a star.
  36. 36. Two types of devices that provide a common central connection point to all the other devices on the network are a hub and a switch. Hub / Switch Star Network Topology
  37. 37. The device that provides a common central connection point for other devices on a network. All data that transfers from one device to another passes through the hub or switch. The hub takes a signal that comes from any device and passes it along to all the other devices in the network. Hub / Switch Hub / Switch Star Network Topology
  38. 38. Advantages: 1. If one device fails, only that device is affected. 2. Devices can be added to or removed from network with little or no disruption. 3. Easy to troubleshoot and isolate problem. Star Network Topology
  39. 39. Disadvantages: 1. If the hub or switch fails, the entire network will be inoperabled. 2. Requires more cable than most of the other topologies. 3. More expensive because of the cost of the hub/switch. Star Network Topology
  40. 40. Ring Network Topology On a ring network, a cable forms a closed loop (ring) with all computers and devices arranged along the ring.
  41. 41. Data transmitted on a ring network travels from device to device around the entire ring, in one direction (clockwise or counterclockwise) Token passing is one method for sending data around a ring Each device takes a turn sending and receiving information through the use of a token. Ring Network Topology
  42. 42. The token along with any data is sent from the first device to the second device which extracts the data addressed to it and adds any data it wishes to send. Then second device passes the token and data to the third device, etc. until it comes back around to the first device again. Only the device with the token is allowed to send data . All other devices must wait for the token to come to them. Ring Network Topology
  43. 43. Ring Network Topology
  44. 44. Advantages: 1. The transmission of data is relatively simple as packets travel in one direction only. 2. Cable faults are easily located, making troubleshooting easier. 3. The uses of token passing enables all devices in a ring topology to share the network resources fairly. Ring Network Topology
  45. 45. Disadvantages: 1. A failure in any cable or device breaks the loop and can take down the entire network. 2. Data packets must pass through every computer therefore, this makes it slower. 3. A ring network can span a larger distance than a bus network, but it is more difficult to install. Ring Network Topology
  46. 46. DEFINITION ADVANTAGES DISADVANTAGES A bus network consists of a single central cable (backbone), to which all computers and other devices connect. Inexpensive and easy to install. There might be disruption when computer or other devices are added or removed. Other devices ca be attached or detached without disturbing the network. Failure of one device usually does not affect the rest of the network. The break in the main cable(backbone) will prevent all systems from accessing the network. It is difficult to identify the problem if the entire network Shut down. Summary: BUS NETWORK TOPOLOGY
  47. 47. DEFINITION ADVANTAGES DISADVANTAGES All the computers and other devices on the network connect to a central device, thus forming a star. If one device fails, only that device is affected. If the hub or switch fails, the entire network will be inoperabled. Devices can be added or removed from network with no disruption. Easy to troubleshoot and isolate problem. Requires more cables than most of the other topologies. More expensive because of the cost of hub/switch. Summary: STAR NETWORK TOPOLOGY
  48. 48. Summary: DEFINITION ADVANTAGES DISADVANTAGES On a ring network, a cable forms a closed loop (ring) with all computers and devices arranged along the ring. Transmission of data is simple as packets travel in one direction only. A failure in any cable or device breaks the loop and can take down entire network. Cabel faults are easily located, making troubleshooting easier. All devices in ring topolgy share the network resources fairly. Data packets must pass through every computer, thus make it slower. More difficult to install than a bus network. RING NETWORK TOPOLOGY
  49. 49. Chapter Three 3.1 Network Basic 3.1.4 Classification of Network At the end of this topic, students should be able to: Differentiate among Local Area Network (LAN), Metropolitan Area Network (MAN) and Wide Area Network (WAN)
  50. 50. Networks typically are classified as: a) LOCAL AREA NETWORK • Definition • Types of LAN: – Personal area network (PAN) – Home area network (HAN) • Advantages and Disadvantages of LAN b) METROPOLITAN AREA NETWORK • Definition • Type of MAN – Campus network • Advantages and Disadvantages of MAN c) WIDE AREA NETWORK • Definition • Types of WAN – Enterprise private network – Virtual private network • Advantages and Disadvantages of WAN
  51. 51. MAN LAN LAN LAN MAN LAN LAN LAN MAN LAN LAN LAN
  52. 52. LOCAL AREA NETWORK
  53. 53. • A local area network (LAN) is a network that connects computers and devices in a limited geographical area • A wireless LAN (WLAN) is a LAN that uses no physical wires Discovering Computers : Chapter 9 53• Page 472 • Figures 9-10 – 9-11
  54. 54. • Normally used bus network. Discovering Computers : Chapter 9 54• Page 472 • Figures 9-10 – 9-11
  55. 55. Advantages • Easy to share devices (printers, scanners, external drives) • Easy to share data (homework, pictures) • Cost of LAN Setup is low. LOCAL AREA NETWORK
  56. 56. Disadvantages • Power - a good LAN is required to be ‘ON’ all the times. • Security - each computer and device become another point of entry for undesirables. • if all computers running at once, can reduce speed for each. • Area covered is limited LOCAL AREA NETWORK
  57. 57. METROPOLITAN AREA NETWORK
  58. 58. • A metropolitan area network (MAN) is a high- speed network that connects local area networks in a metropolitan area such as a city or town and handles the bulk of communications activity across that region. Discovering Computers : Chapter 9 58• Page 473 • Figure 9-12
  59. 59. Example of a MAN
  60. 60. Example of a MAN • Surveillance System • Traffic Light Monitoring System • Cable Network TV
  61. 61. Type of MAN Campus Area Network (CAN) • A campus network is a computer network made up of an interconnection of local area networks (LAN's) within a limited geographical area.
  62. 62. • In the case of a university campus-based campus network, the network is likely to link a variety of campus buildings including; academic departments, the university library and student residence halls. Type of MAN Campus Area Network (CAN)
  63. 63. Example: Campus Area Network (CAN) Academic Departments University Library Student Residence Halls.
  64. 64. Advantages • efficiency and shared access. • All the computer-owning residents of the area have equal ability to go on line. METROPOLITAN AREA NETWORK
  65. 65. Disadvantages • it can be costly (hardware, software, support, etc.). • security problems • As the network consists of many computers over the span of a city, the connection can lag or become quite slow. METROPOLITAN AREA NETWORK
  66. 66. WIDE AREA NETWORK
  67. 67. A wide area network (WAN) is a network that covers a large geographic area (such as a city, country, or the world) using a communications channel that combines many types of media such as telephone lines, cables, and radio waves. The Internet is the world’s largest WAN
  68. 68. Advantages • increased efficiency, ease of communication, and lowered costs. WIDE AREA NETWORK
  69. 69. Disadvantages • security problems • training costs • maintenance problems. Large enterprises will dedicate personnel to maintaining their WAN. WIDE AREA NETWORK
  70. 70. How Are LAN, MAN, and WAN Different?
  71. 71. How Are LAN, MAN, and WAN Different? • The main differentiation among these classifications is their area of coverage. LAN, MAN and WAN compared
  72. 72. CRITERIA Geographical Area Provider LAN Connects computers and devices in a limited geographical area such as computer laboratory. No provider MAN Connects computers and devices in a metropolitan area such as town or city. Single provider WAN Connects computers and devices in a large geographical area such as country, world. Multi-provider Comparison:
  73. 73. CRITERIA Connectivity Technology LAN Computers are located within the same building, usually connected through wires. Ethernet, token ring, FDDI, Wifi MAN Computers connected via telephone lines or modems, fiber optic, cable television. ATM, SMDS, FDDI WAN Computers connected via satellite or Internet. Circuit Switched, Packet Switched Comparison:

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