communications

communications

1. networks

   • LAN
     • a Local Area Network is a network confined to one location or organisation.
       • it's resources are only accessible by computers on that LAN

2. WAN

   • a Wide Area Network is a network of LAN's spanning a wide area
   • the internet is an example

3. wired

   • computer are connected by physical wires

4. wireless

   • radio waves are used to transmit binary data

5. bus topology

   • this is where all the components on a network ore connected on one cable.
   • advantages are that it is cheap, easy to install and no extra equipment is required
   • disadvantage are that there is a high chance of collisiomns with more computers added as well, if there is a damage in the wire is will cause failure and is only suitable for small networks.

6. ring network- topology

   • a ring network is where all the components are each connected separately to the component to the left of the in a ring formation
   • advantages are that there is no collisions each cable has one computer, the number of computers does not effect the speed.
   • disadvantages are that one faulty cable or computer will result in failure and is more difficult to add more computers.

7. star network- topology

   • is where all the components in a network are controlled by a hub or switch and each component is connected to the hub/switch at the same time
   • advantages are there are no collisions, failure of a cable is not catastrophic and is easy to add new computers
   • disadvantages are that it is expensive and failure of hub/switch is hard to fix and cause failure

8. mesh topology

   • mesh topology is where all the components in a networks are connected to multiple other networks at the same time
   • advantages are that there are no collisions and if there is a brake in the cable there is no major failure
   • disadvantages are that it is very expensive in comparison to the other topologies and it takes a lot of time to replace a component in the topology

9. pathfinding

   • circuit switching
     • a path across the network is established , the path is locked and remains open for the duration of the communication
   • packet switching
     • the data is split into lots of small chunks called packets, each one is sent independently likely using different paths. The packets are reassembled at the other side.

10. network hardware

    • a switch- routes packets round a network by analysing them and sending them to the device they are addressed to
    • a hub- routes packets round a network by blindly sending them to every device it's connected to.
    • a bridge connects together two networks that use the same base protocols.
    • a gateway connects together two networks that use different base protocols
    • a router stores the addresses of computers on its network and transfers their data to devices on other networks
    • a Wireless Access Point (WAP) is a device that creates a wireless network and allows other devices to connect
    • a Network Interface Card (NIC) is a device that joins the network and connects to a computer or other device