NETWORKS

NETWORKS

1. WAN

   • WIDE AREA NETWORK
   • a network over a large area or multiple organisations

2. LAN

   • LOCAL AREA NETWORK
   • a network based in a small location or single organisation

3. Topologies

   • Bus topology
     • The network consists of a single cable that runs through the network and all devices attach to this single cable
     • Advantages
       • Cheap to install (only one wire needed)
     • Disadvantages
       • High chance of catastrophic failure (a break in the central cable takes out the entire network)
       • High chance of collisions (multiple communications on the same cable that corrupt each other, slowing down the network)
       • More computers mean more collisions, so the network gets slower as it gets bigger
   • Ring topology
     • Computers are connected to each other in a ring and the communication only goes in one direction
     • Each computer receives a message, and if it is not the intended recipient, passes it on to the next computer and there is no central cable, each connection is between two computers
     • Advantages
       • Cheap to install (one cable per computer)
       • No collisions - only one computer is transmitting on each cable
     • Disadvantages
       • High chance of catastrophic failure (if any cable breaks or any computer goes down, the entire network fails
       • Difficult to add new computers
   • Star topology
     • All computers are connected to a central switch, the switch directs the traffic to the appropriate computer
     • Advantages
       • Fast (low chance of collisions)
       • Easy to add new computers
       • Low chance of catastrophic failure (a broken cable only takes out one computer, the rest of the network is fine)
     • Disadvantages
       • Expensive (needs a lot of cabling, and a central switch, which is expensive)
       • Failure of the switch will take down the network