Computer Networks


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This the ppt I made for my ICT formatives. I hope you'll like it!

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Computer Networks

  1. 1. What is a computer network? A network connects several nodes or networking devices together. This allows sharing of resources such as printers, storage memory, etc.
  2. 2. Different Types of Networks • LAN (Local Area Network) Also includes WLAN (Wireless LAN) • WAN • MAN In this presentation we will only be looking at LAN, WAN and WLAN.
  3. 3. LAN (Local Area Network) • It is a small network with a maximum coverage of about a few buildings. • Allows sharing of printers, medium sized files, etc. • Mainly used in offices and schools. • Advantages: sharing of resources, communication increases, controlled by an administrator. • Disadvantages: malware threat, queues, slower access to external networks, lesser data security compared to stand alone computers, if there is a break-down of a node then the network will brake.
  4. 4. Topologies of LAN • Bus Topology • Ring Topology • Star Topology
  5. 5. Bus Topology Computers are connected to a main line Data moves towards the destination node A Terminator is often used here. It is a device used at the ends of the main line to avoid signal bounce which can lead to data interference.
  6. 6. (continued) Advantages: easy to add new node, entire network will not get affected with the failure of one node, less cables required, cost efficient. Disadvantages: if main line malfunctions the entire network will fail, more nodes will decrease speed, difficult to isolate a fault on a particular device or computer.
  7. 7. Ring Topology It’s a chain of nodes cabled together to form a loop/ring. Each computer receives data only relevant to it as each computer has a unique identification number.
  8. 8. (continued) Advantages: functions efficiently even with heavy data load, suitable for larger networks. Disadvantages: networks can fail of there is a cable fault, addition of new node is difficult as it has to be placed between existing ones.
  9. 9. Star Topology Each node is connected to each other by a hub or a switch. Every node has its own connection to the hub. Advantages: if one node fails the entire network is not affected, easy to work on a faulty node and isolating it, network can be easily expanded Disadvantage: break down of hub will lead into full network crash Hub/Switch
  10. 10. WAN(Wide Area Network) A network over a large area such as cities, countries, etc. Connected by a router or a modem Expensive because of additional hardware and operating system E.g.: Internet
  11. 11. WLAN (Wireless Local Area Network) Communication is made over short distances with either radio or infrared signals instead of cables. Ranges of different signals • Radio: 30-50 metres • Infrared: 1-2 metres A device called Access Point is connected to such networks. Advantages: all computers can access that same material, less cabling, flexibility, adding new device is easy. Disadvantages: big security threat if network is unprotected, signals can be interfered with, transfer rate is less
  12. 12. Network Devices Modem (Modulator Demodulator): converts digital signals in to analogue signals (modulation) and vice versa (demodulation). Network Hub: connects numbers of nodes from where it receives of one device and sends it to all devices. Switches: connects numbers of nodes from where it receives data and sends it to the relevant node. Routers: used to connect networks together and to the Internet.
  13. 13. THANK YOU!