NETWORKS

NETWORKS

1. ADVANTAGES

   • SHARE FILES
     • the same files are available on every computer
   • SHARE RESOURCES
     • e.g printers and internet connection
   • SHARE LOGINS
     • same username and password can be used on every computer on the same network

2. DISADVANTAGES

   • COST
     • network is expensive to set up
   • INCREASED RISK
     • viruses can quickly affect the computer
   • DIFFICULTY
     • expertise needed for set up and to maintain network

3. TYPES OF NETWORK

   • LAN
     • Local Area Network
       • a network in a small area/single organisation
   • WAN
     • Wide Area Network
       • a network in a large area/ multiple organisations

4. TOPOLOGIES

   • BUS TOPOLOGY
     • a single cable that runs through the network. All devices attach to this one cable.
       • ADVANTAGES
         • cheap to install - only 1 cable
       • DISADVANTAGES
         • high chance of catastrophic failure, high chance of collisions (slow), more computers means more collisions, so the bigger the network the slower
   • RING TOPOLGY
     • computers are connected to each other in a ring. Every message gets sent to every computer and if its not the intended computer it gets passed onto the next device. There is also no central cable, so each connection is inbetween two computers.
       • ADVANTAGES
         • cheap to install - 1 cable per computer, no collisions - only one computer is transmitting on each cable
       • DISADVANTAGES
         • high chance of catastrophic failure - if one cable breaks the whole network fails, hard to add new computers(expand)
   • STAR TOPOLOGY
     • all computers are connected to a central switch. The switch directs the message to the correct computer.
       • DISADVANTAGES
         • expensive- central switch and lots of cabling, failure of the switch will fail the whole network
       • ADVANTAGES
         • low chance of data collisions(fast), low chance of catastrophic failure- broken cable only takes out one computer extendable- easy to add new computers

5. IP ADDRESSES

   • A unique value assigned to every computer on a network, used to identify it
   • messages on a network have an IP address attached, which is how a computer knows whether or not to keep the message.
   • PROBLEMS
     • the internet is a huge network with more devices than its possible to assign a unique address to. To solve this, unique addresses are assigned to businesses and houses. These houses and businesses run their own mini-network with different IP addresses.

6. THE INTERNET

   • ROUTING
     • a cost is assigned to each connection in a mesh.
     • route-finding algorithms are used to find the lowest cost route between two nodes.
   • PACKETS
     • data is split into small chunks called packets.
     • Each packet is sent along the lowest cost route and the packets are reassembled on the other side.
   • MESH TOPOLOGY
     • the internet is a giant mesh of computers. It is impossible to break the internet, since another route can always be found.
     • there are multiple different routes between any two nodes.