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NETWORK

NETWORK. Network is a group of two or more computers or communicating devices that are able to communicate with each other. The computers on a network may be linked through cables, telephone lines, radio waves or satellites. Computer networks allow people to :

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NETWORK

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  1. NETWORK Network is a group of two or more computers or communicating devices that are able to communicate with each other. The computers on a network may be linked through cables, telephone lines, radio waves or satellites. Sunil Kumar Sahu,Lecturer RCET

  2. Computer networks allow people to: · Exchange information (for example, databases, documents, and graphics) via connected workstations. · Share resource equipment (for example, computers, printers and scanners). · Use shared applications (for example, spreadsheets and word processing programs). · Collaborate and communicate electronically. Sunil Kumar Sahu,Lecturer RCET

  3. Components of networks • A computer network comprises the following components: • A minimum of at least 2 computers. • Cables that connect the computers to each other, although wireless communication is becoming more common. • A network interface device on each computer (this is called a network interface card or NIC). • A ‘Switch’ used to switch the data from one point to another. Hubs are outdated and are little used for new installations. • Network operating system software Sunil Kumar Sahu,Lecturer RCET

  4. Network Criteria • Performance • Mostly measured by throughput and delay • Reliability • The frequency of failure • Recovery time from a failure • Security • Protecting data from • unauthorized access • Damage Sunil Kumar Sahu,Lecturer RCET

  5. Different Types of Networks • Depending upon the geographical area covered by a network, it is classified as: – Local Area Network (LAN) – Metropolitan Area Network (MAN) – Wide Area Network (WAN) – Personal Area Network (PAN) Sunil Kumar Sahu,Lecturer RCET

  6. LAN • LAN stands for Local Area Network. • A LAN is group of computers and networks devices connected together usually within same building. • LAN is high speed and inexpensive. • It uses guided media. • Waves are guided along solid medium such as twisted pair cable/coaxial cable/fiber optic cable. • Ex. University,school,computer lab etc. • Speed of LAN is 100 to 1Gbps. • Is limited in size, typically spanning a few hundred meters,and no more than a mile. • It Has lower cost compared to MAN’s or WAN’s. Sunil Kumar Sahu,Lecturer RCET

  7. LAN’s can be either wired or wireless. Twisted pair,coaxor fibre optic cable can be used in wired LAN’s. • Nodes in a LAN are linked together with a certain topology. These topologies include: – Bus – Ring – Star Sunil Kumar Sahu,Lecturer RCET

  8. Local Area Network Sunil Kumar Sahu,Lecturer RCET

  9. Local Area Networks 9 Sunil Kumar Sahu,Lecturer RCET

  10. Advantages of LAN • Speed • Cost • Security • E-mail • Resource Sharing Sunil Kumar Sahu,Lecturer RCET

  11. Disadvantages of LAN • Expensive To Install • Requires Administrative Time • File Server May Fail • Cables May Break Sunil Kumar Sahu,Lecturer RCET

  12. MAN • MAN stands for Metropolitan Area Network. • A MAN is larger network that usually span several building in the same city or town. • A MAN is optimized for a larger geographical area than a LAN, ranging from several blocks of buildings to entire cities. • Is larger than a LAN, but smaller than a WAN. • Slow in compare to LAN and inexpensive. • Connected with Fiber Optics Cable. • Used may be guided or may be unguided media. • Ex.-cable tv, or large companies with multiple buildings etc. Sunil Kumar Sahu,Lecturer RCET

  13. Sunil Kumar Sahu,Lecturer RCET

  14. WAN • WAN stands for Wide Area Network. • WAN covers a large geographic area such as country, continent or even whole of the world. • A WAN is two or more LANs connected together. • A WAN is confined within the bounds of state or country. • A WAN is generally slow and relatively expensive. • The Internet is an example of WAN. • Use unguided media i.e.Waves are propagated through atmosphere. • WAN Connected using Internet,Satellite or ISDN land line. Sunil Kumar Sahu,Lecturer RCET

  15. Sunil Kumar Sahu,Lecturer RCET

  16. PAN • PAN stands for PERSONAL AREA NETWORK. • A PAN is a network that is used for communicating among computers and computer devices (including telephones) in close proximity of around a few meters within a room. • PAN’s can be wired or wireless Sunil Kumar Sahu,Lecturer RCET

  17. PAN Sunil Kumar Sahu,Lecturer RCET

  18. What is I N T E R N E T ? • The largest network of networks in the world. Sunil Kumar Sahu,Lecturer RCET

  19. What is I N T E R N E T ? • A network of networks, joining many government, university and private computers together and providing an infrastructure for the use of E-mail, bulletin boards, file archives, hypertext documents, databases and other computational resources. Sunil Kumar Sahu,Lecturer RCET

  20. Vinton Cerf • Father of Internet • Co-designer of the TCP/IP networking protocol. Sunil Kumar Sahu,Lecturer RCET

  21. Applications Of Internet • Download programs and files • E-Mail • Voice and Video Conferencing • E-Commerce • File Sharing • Information browsing • Search the web addresses for access through search engine • Chatting and many more… Sunil Kumar Sahu,Lecturer RCET

  22. Disadvantages of Internet • Theft of personal information such as name, address, credit card number etc. • Virus threats nothing but a program which disrupts the normal functioning of your system. • Spamming refers to receiving unwanted e-mails in bulk, which provide no purpose and needlessly obstruct the entire system. • Pornography This is perhaps the biggest threat related to children’s healthy mental life. A very serious issue concerning the Internet. Sunil Kumar Sahu,Lecturer RCET

  23. Applications of an Intranet • Human resources management • Sales and marketing • Production and operations • Accounting and finance • Help organizations move from a calendar- or schedule-based document-publishing strategy to one that’s based on events or need • Reduce the costs and time of document production Sunil Kumar Sahu,Lecturer RCET

  24. Internet Services • Electronic Mail (e-mail) • World Wide Web • Telnet • File Transfer Protocol (FTP) • Internet Telephone • Web TV/Radio • Internet Relay Chat • News Groups • Video conferencing Sunil Kumar Sahu,Lecturer RCET

  25. Electronic Mail (e-Mail) • Distributes e-mail messages and attached files to one or more electronic mailboxes. • Eg:- e-mail addresses • thomas@mes.edu.in • murugan@mesmarampally.org Sunil Kumar Sahu,Lecturer RCET

  26. Electronic Mail (e-Mail) thomas @ mes . edu . in murugan @ mesmarampally . org Type of Organization Country Name of Person Organization Sunil Kumar Sahu,Lecturer RCET

  27. Electronic Mail (e-Mail) • Different e-mail service providers • G-Mail • Yahoo Mail • Hot Mail Sunil Kumar Sahu,Lecturer RCET

  28. Sunil Kumar Sahu,Lecturer RCET

  29. World Wide Web (W WW) • Most important service provided by Internet. • An internet-based hypermedia initiative for global information sharing. • Developed in 1989 by Tim Berners-Lee of the European Particle Physics Lab (CERN) in Switzerland. Sunil Kumar Sahu,Lecturer RCET

  30. Tim Berners-Lee • Father of W W W. • The inventor of HTML. • Invented W W W while working at CERN, the European Particle Physics Laboratory. Sunil Kumar Sahu,Lecturer RCET

  31. Search Engines • For searching information on the Internet. • Google • Yahoo • Altavista Sunil Kumar Sahu,Lecturer RCET

  32. Sunil Kumar Sahu,Lecturer RCET

  33. Impact of Internet • Education • Health Care • Business Sunil Kumar Sahu,Lecturer RCET

  34. Intranet • It is an internal network that is setup internally for companies and can be accessed by employees for the purpose of standard documents or information and many items of information and data. Sunil Kumar Sahu,Lecturer RCET

  35. Table 7.2 The Internet versus Intranets The Internet versus Intranets

  36. EXTRANET A network based on Web technologies that links selected resources of the intranet of a company with its customers, suppliers, or other business partners. Sunil Kumar Sahu,Lecturer RCET

  37. Extranets • Advantages of extranets: • Coordination • Feedback • Consumer satisfaction • Cost reduction • Expedited communication Sunil Kumar Sahu,Lecturer RCET

  38. TRANSMISSION MODE • The term transmission mode defines the direction of the flow of information between two communication devices i.e. • It tells the direction of signal flow between the two devices. Sunil Kumar Sahu,Lecturer RCET

  39. Transmission Modes • The term transmission mode refer to the manner in which data is sent over the underlying medium. • Transmission modes can be divided into two fundamental categories: 1. Serial 2.Parallel • Figure 9.1 gives an overall taxonomy of the transmission modes. Sunil Kumar Sahu,Lecturer RCET 39

  40. A Taxonomy of Transmission Modes Sunil Kumar Sahu,Lecturer RCET 40

  41. Parallel Transmission • Parallel transmission allows transfers of multiple data bits at the same time over separate media • In general, parallel transmission is used with a wired medium that uses multiple independent wires. • Furthermore, the signals on all wires are synchronized so that a bit travels across each of the wires at precisely the same time. • Figure 9.2 illustrates the conceptof parallel transmission. Sunil Kumar Sahu,Lecturer RCET

  42. Figure 4.32 Parallel transmission Sunil Kumar Sahu,Lecturer RCET

  43. Parallel Transmission • A parallel mode of transmission has two important advantages: • High speed: it can send N bits at the same time • Match to underlying hardware: Internally, computer and communication hardware uses parallel circuitry. Sunil Kumar Sahu,Lecturer RCET 43

  44. PARALLEL TRANSMISSION • Disadvantage- there is a significant disadvantage: cost. Parallel transmission requires n communication lines (wires in the example) just to transmit the data stream. Because this is expensive, parallel transmission is usually limited to short distances. Sunil Kumar Sahu,Lecturer RCET

  45. Serial Transmission • Serial transmission • sends one bit at a time • we need only one communication channel rather than n to transmit data between two communicating devices • Figure 9.3 illustrates the configuration Sunil Kumar Sahu,Lecturer RCET 45

  46. Figure 4.33 Serial transmission Sunil Kumar Sahu,Lecturer RCET

  47. Serial Transmission • The advantage of serial over parallel transmission is that with only one communication channel, serial transmission reduces the cost of transmission over parallel by roughly a factor of n. • Since communication within devices is parallel, conversion devices are required at the interface between the sender and the line (parallel-to-serial) and between the line and the receiver (serial-to-parallel). Sunil Kumar Sahu,Lecturer RCET

  48. Serial Transmission • Serial transmission occurs in one of three ways: 1. asynchronous 2. synchronous 3. isochronous. Sunil Kumar Sahu,Lecturer RCET

  49. ASYNCHORONOUS TRANSMISSION • Sends only one character at a time (one byte of data at a time) • Synchronize two devices using Start Bit and Stop Bit. • Start bit refers to the start of the data. Usually 0 is used for start bit. • Stop bit indicates the end of data, more than one bit can be used for end. Sunil Kumar Sahu,Lecturer RCET

  50. Figure 4.34 Asynchronous transmission Sunil Kumar Sahu,Lecturer RCET

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