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Unit2

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basics of computers

basics of computers

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  • 1. Computer Networks
  • 2. Computer Network A computer network is defined as the interconnection of 2 or more independent computers or/and peripherals.
  • 3. Network Source Destination
  • 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. 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. Network Topology The way in which the computers are interconnected together is known as TOPOLOGY.
  • 7. Types of topologies • Physical topology • Logical topology
  • 8. Types of physical topologies • Bus/Linear • Star • Ring • Tree • Mesh
  • 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. 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. 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. 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. 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. 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. 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. Advantages of a Tree Topology • Point-to-point wiring for individual segments. • Supported by several hardware and software venders.
  • 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. 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. Advantages of ring topology • Requires lesser amount of cable and there are not much of installation problems • All stations have equal access
  • 20. Disadvantages of ring topology • Failure of one computer may impact others • Data transfer is slow
  • 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. Advantages of mesh topology • Ease of troubleshooting. • Data transfer is faster.
  • 23. Disadvantages of mesh topology • uses a lot of cabling. • Complex • Most expensive topology
  • 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. 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. Transmission Technology 1. Point to Point Network Data is routed directly from source machine to destination machine directly. Dedicated link