Networks

Networks

1. LAN

   • Small geographical area
   • Owned by the organisation
   • Find them in schools, businesses and homes
   • Advantages
     • Sharing files is easier
     • Share the same hardware
     • Install and update software all at once
     • Communicate easily
   • Local area network
   • Can be wired or wireless

2. WAN

   • Connects LANs from different locations
   • Wide area networks
   • Organisations hire the infrastructure
   • The internet is one big WAN
   • More expensive
   • Connected with wires

3. Hardware

   • Network Interface Controller
     • Allows a device to connect to a network
     • Built into the computer
   • Switches
     • Receives data
     • Transmits that data to the device with the same MAC address
     • Connects devices on the LAN
   • Routers
     • Transmit data to and from networks
     • Direct packages on the Internet
     • Connect LAN to the internet
   • WAP
     • A switch that connects devices wirelessly
   • Wires
     • Copper
       • Twisted wires to reduce interference
     • Coaxial
       • 1 copper wire covered in insulation
         • To reduce interference
     • Fibre optic
       • Transmit data with light
       • No interference
       • Travel really far
       • Very expensive

4. Performance

   • Bandwidth
     • Amount of data that can be transferred in a given time
     • The greater the bandwidth, higher the performance
     • Bandwidth is shared between devices
     • Too many devices cause congestion
   • Wires
     • Wired connections are faster and more reliable than wireless
     • Fibre is the fastest
       • Coaxial is second
         • Copper is last
   • Wireless
     • Depends on signal quality
     • Affected by the range of the device
       • And by interference from other devices

5. Client servers

   • Devices connected are clients
   • Files are stored centrally on the server
   • Clients send requests to the server
     • It processes and responds
   • Most uses of the internet use this
   • Pros
     • Easier to keep track of files
     • Easy to install software
     • Reliable
   • Cons
     • Expensive to set up
     • Depend on server
     • Server could get overloaded

6. Peer-to-peer

   • All devices are equal
   • Connect directly with each other
   • Share files between devices
   • Pros
     • Easy to maintain
     • No dependence on anyone
   • Cons
     • Need to update individually
     • Lose track of where thigs are stored
     • Machines may slow down
     • Less reliable and might lose data

7. Star Topology

   • All devices are connected to a central switch or server that controls the network
   • Pros
     • If one device fails, none of the others are affected
     • Easy to add more devices
     • Better performance
     • Very few data collisions
   • Cons
     • Every device needs a cable to connect to the server
     • If there's a problem with the server, it affects all
     • Expensive

8. Mesh topology

   • Every device is connected to each other with no central location
   • They send data along the fastest route through other devices
   • There's no single point where the network would fail because the data would just pick a different route
   • Very expensive because of all the cables
   • A full mesh is every device connected
     • A partial mesh is not all devices are fully connected

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