1. Management Information Systems Lection 04 Networks CLARK UNIVERSITY College of Professional and Continuing Education (COPACE)

2. Plan Basic terms Classification of networks Topology of networks Model OSI Types of environmental data

3. Basic terms Computer network is a collection of computers and other hardware interconnected by communication channels that allow sharing of resources and information.

4. Basic terms Server Client Client-server

5. Computer entirely dedicated to servicing the requests of other computers, plays the role of a dedicated server Basic terms

7. 7 The computer that combines the functions of a client and a server, is a peer node. Basic terms

8. Classification of networks Environment data transmission Territorial prevalence Organization of interaction of computers Speed of data transfer

9. Speed of data transfer: High speed (more then 100 Мbit/sec) Middle speed (less then 100 Мbit/sec) Low speed (less then 10 Мbit/sec) Classification of networks

10. Territorial prevalence Urban network (MAN) Speed: dozens Mbit/sec Global networks (WAN) Speed: dozens Kbit/sec – dozens Mbit/sec Local networks (LAN) Speed: 10 Мbit/sec - 10 Gbit/sec Classification of networks

11. Environment data transmission: Wireless network Wires network Classification of networks

12. Organization of interaction of computers: Hybrid network Network with dedicated server Peer-to-peer network Classification of networks

13. Peer-to-peer network

14. Peer-to-peer operating systems include server and client components of network services. Examples:  LANtastic  Windows for Workgroups  Windows NT Workstation  Windows 95/98

15. Advantages: 1. Low price 2. Simplicity of installation and operation Peer-to-peer network Disadvantages: 1. Complexity of the information protection 2. Efficiency depends on the number of computers

16. 1.Number of computers in the network  10-20 1.Security problems are not critical 2.You don’t wait significant expansions of your company When do we use peer-to-peer networks?

17. Network with a dedicated server

18. Advantages: Division of resources Protection Data backup Big number of users Disadvantages:  Necessity of additional OS for the server  High complexity of installation and modernization of the network  Necessity of a separate PC as a server

19. Hybrid network

20. Network topology Network topology describes the physical location of the computers, cables and other network components

21. 21 Network topologies

22. Fully connected topology

23. It is the topology of a network in which each workstation is connected to all the others. The physical fully connected topology is generally too costly and complex for practical networks, although the topology is used when there are only a small number of nodes to be interconnected

24. Topology "bus" is a topology with a common cable (called the bus), which is connected to all workstations. At the ends of the cable there are terminators to prevent signal reflection. Bus topology

25. 25 When building large networks there is a problem if a limited length of cables between nodes, in this case, the network is divided into segments. Segments are connected by various devices - repeaters, concentrators or hubs. For example, the technology allows the use of Ethernet cable up to 185 meters. Bus topology

26. Advantages: a little time of setting up a network the cheapness (requires less cable and network devices) easy set-up the failure of some workstation does not affect the work of the whole network Bus topology Disadvantages: any failures in the network, as the cable break, leads to the failure of the whole network complex localization of faults The network performance falls with the addition of new workstations

27. "Star“ is the basic topology of a network in which all computers are connected to the central node (usually a switch or a hub), forming a physical network segment. This segment can function both individually and like a part of a complex topology as “tree”. Star topology

28. 24-port switch

29. Better performance Isolation of devices We can increase the size of the network very easily. Easy to detect faults and to remove parts. Advantages of star networks

30. Disadvantages of star networks  failure of the central switch will result to an inability of the network (or network segment)  it often requires more cable than for most other topologies  number of workstations in the network (or network segment) is limited by the number of ports in the central switch

31. Ring is the basic topology of a network in which workstations are connected sequentially to each other, forming a closed network. Ring topology

32. ease of installation practically complete absence of the additional equipment the possibility of stable work without a significant drop in speed of data transmission with heavy network traffic Advantages of ring topology

33. Disadvantages of ring topology  the failure of a single workstation, and other problems (the cable break) leads to the failure of the whole network  the complexity of the configuration and customization  the complexity of troubleshooting

34. Star-bus (hybrid) topology

35. Tree topology

36. OSI model In 1984 the number of international standardization organizations (ISO, ITU-T and others) developed the Open System Interconnection model (OSI). The OSI model defines the different levels of interoperability, gives them the standard names and indicates which functions levels must perform.

37. OSI levels

38. Physical layer It means the transferring of bits by physical channels, such as a coaxial cable, “twisted pair”, optic cable, wireless networks.

39. Data link level This level is a very powerful and complete set of functions for sending messages between network nodes. It gives us the opportunity of detection and correction of errors. Bits are grouped into sets called frames

40. Network layer Agreement of different technologies simplification of addressing in large networks. Creation of reliable and flexible barriers on the way of unwanted traffic between networks. Messages on this level are called packages

41. Transport layer guaranteed delivery of data (it gives an acknowledgement of reception of packages) detection of errors at the level of the sender and recipient (it allows the host system to detect bad packages)

42. Session layer It manages the dialogue, i.e. it fixes which side is currently active and provides the synchronization

43. Presentation layer It works only with the form of data, without changing the its content. The information is always clear to the application layer of another system. Can overcome the syntactic differences in the data models, or differences in the codes of characters, such as ASCII codes Encrypt data

44. Application layer It gives a set of protocols which allow users an access to shared resources, such as files, printers or web-pages, and organizes their work together

45. Types of networks: Wires networks Wireless networks

47. Coaxial cable

49. Twisted pair

50. Optic fiber cable

51. Wireless networks The difficulty of cable laying Mobility Remoteness Urgency

52. Bluetooth Bluetooth is designed for the construction of personal wireless networks (Wireless Personal Area Network, WPAN). The coverage is up to 100 m Line of sight is not required Bluetooth works on the none-licensed in the whole world frequency of 2.45 GHz, which allows free usage of the bluetooth device. The speed of 721 Kbps and the transfer of 3 voice channels

53. Wi-Fi The most widespread technology of the organization of wireless networks is WI-FI. Speed of data transmission depends on the distance between the points, and on other factors, for example, on the level of interference. At a speed of 54 Mbit/s, which is the limit for WI-FI, the range is 30 to 50 m. The distance increases up to several hundreds of meters at a speed of 1 Mbit/sec.

54. IR-port IrDA (Infra red Data Association) allows you to connect to peripherals without cables using infrared waves. IrDA port operates at data rates 2400-115200 bit/sec. The main disadvantage is the need for direct line of sight between the transmitter and receiver.