Networks

Networks

1. The types of network

   • LAN (Local Area Network)
     • School network
   • WAN (Wide Area Network)
     • TheInternet

2. A network is two or more computers joined together

3. Network topologies

   • BUs Network
     • All computers, printers etc joined to one cable. Has terminators to stop signals reflecting back down the bus
     • Advantages
       • Easy to install
       • Cheap (doesn't require much cable)
     • Disadvantages
       • If the main cable is damaged then the whole network fails
       • As more workstations are connected the performance of the network will become slower because of data collisions
       • Every workstation on the network "sees" all of the data on the network – this is a security risk
   • Ring network
     • In a ring network each device (workstation, server, printer) is connected to two other devices, this forms a ring for the signals to travel around. Each packet of data on the network travels in one direction and each device receives each packet in turn until the destination device receives it.
     • Advantages
       • Can transfer data quickly
       • Cheapest to create / set up
       • No data collisions
     • Disadvantages
       • If the main cable fails or any device is faulty then the whole network will fail.
   • Star network
     • In a star network each device on the network has its own cable that connects to a switch or hub. A hub sends every packet of data to every device, whereas a switch only sends a packet of data to the destination device.
     • Advantages
       • Very reliable – if one cable or device fails then all the others will continue to work
       • High performing as no data collisions can occur
     • Disadvantages
       • Expensive to install as this type of network uses the most cable (network cable is expensive)
       • Extra hardware required (hubs or switches) which adds to cost
       • If a hub or switch fails all the devices connected to it will have no network connection

4. Advantages of a network

   • You can share things like printers
   • Software licenses are cheaper than lots of standalone licenses
   • Files can be easily shared
   • Network users can communicate via email and IM
   • High level of security
   • Data is easy to back up as all the data is stored on the file server

5. Disadvantages of a network

   • Viruses can spread quickly through large WAN’s
   • Viruses can spread quickly through large WAN’s
   • Managing a large network can be difficult, requiring training and a network manager
   • If a file server breaks down all the files become inaccessible
   • Hacking is a risk

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