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basics of computers

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  1. 1. Computer Networks
  2. 2. Computer Network A computer network is defined as the interconnection of 2 or more independent computers or/and peripherals.
  3. 3. Network Source Destination
  4. 4. Need of Networks – Communicate and collaborate – Share information – Share resources – Sharing computer files and disk space – Sharing high-quality printers – Access to common fax machines – Access to common modems – Multiple access to the Internet
  5. 5. Classification of Networks – Local Area Networks (LANs) - a computer network covering a small geographic area, like a home, office, or group of buildings. Typically within 5-mile radius. – Metropolitan Area Networks (MANs)- are large computer networks usually spanning a city. (within 30 miles) – Wide-Area Networks (WANs) - any network whose communications links cross metropolitan, regional, or national boundaries.
  6. 6. Network Topology The way in which the computers are interconnected together is known as TOPOLOGY.
  7. 7. Types of topologies • Physical topology • Logical topology
  8. 8. Types of physical topologies • Bus/Linear • Star • Ring • Tree • Mesh
  9. 9. Linear or bus topology • Consists of a main cable, known as backbone cable, with a terminator at each end . • All nodes (file server, workstations, and peripherals) are connected to the cable. • Ethernet and LocalTalk networks use bus topology.
  10. 10. Advantages of Bus Topology • Easy to connect a computer or peripheral to a linear bus. • Requires less cable length. • Easy to extend. • If one node of the N/W is faulty, the N/W can still remain working.
  11. 11. Disadvantages of Bus Topology • Entire network shuts down if there is a break in the main cable. • Terminators are required at both ends of the backbone cable. • Difficult to identify the problem if the entire network shuts down. • Not meant to be used as a stand-alone solution in a large building.
  12. 12. Star topology • A star topology is designed with each node (file server, workstations, and peripherals) connected directly to a central network hub. • Data on a star network passes through the hub before continuing to its destination. • The hub manages and controls all functions of the network. • It also acts as a repeater for the data flow.
  13. 13. Advantages of Star Topology • Easy to install. • No disruptions to the network other than connecting or removing devices. • Easy to detect faults and to remove parts.
  14. 14. Disadvantages of Star Topology • Requires more cable length than a bus topology. • If the hub fails, nodes attached are disabled. • More expensive than bus topology because of the cost of the hub.
  15. 15. Tree Topology • A tree topology combines characteristics of bus and star topologies. • It consists of groups of star-configured workstations connected to a bus backbone cable. • Tree topologies allow for the expansion of an existing network.
  16. 16. Advantages of a Tree Topology • Point-to-point wiring for individual segments. • Supported by several hardware and software venders.
  17. 17. Disadvantages of Tree Topology • Overall length of each segment is limited by the type of cabling used. • If the backbone line breaks, the entire segment goes down. • More difficult to configure than other topologies.
  18. 18. Ring topology • Is a type of computer network configuration where each network computer and device are connect to each other forming A large circle. • Data is divided into packets when transmitted. • Packet is sent around the ring until it reaches its final destination.
  19. 19. Advantages of ring topology • Requires lesser amount of cable and there are not much of installation problems • All stations have equal access
  20. 20. Disadvantages of ring topology • Failure of one computer may impact others • Data transfer is slow
  21. 21. Mesh topology • It requires that every terminal should be attached to each other. • All the computers must have adequate number of interfaces for the connections to be made. • Because of this requirement the installations is somewhat difficult. • The length of cable required is quite higher as compared to other topologies.
  22. 22. Advantages of mesh topology • Ease of troubleshooting. • Data transfer is faster.
  23. 23. Disadvantages of mesh topology • uses a lot of cabling. • Complex • Most expensive topology
  24. 24. Considerations When Choosing a Topology • Money. A linear bus network may be the least expensive way to install a network; you do not have to purchase concentrators. • Length of cable needed. The linear bus network uses shorter lengths of cable. • Future growth. With a star topology, expanding a network is easily done by adding another concentrator. • Cable type. The most common cable in schools is unshielded twisted pair, which is most often used with star topologies.
  25. 25. Transmission Technology Two types of transmission technologies are there: 2. Broadcast Network Single communication channel is shared by all the machines in the network.
  26. 26. Transmission Technology 1. Point to Point Network Data is routed directly from source machine to destination machine directly. Dedicated link