Networks

Networks

1. Circuit Switching

   • Data arrives in the order it was sent
   • Data arrives at a consistent speed
   • Can start reading transmission as soon as first bit arrives, as data arrives sequentially
   • Only one transmission at a time along each channel – clogs the network

2. Topologies

   • Bus
     • High chance of collisions
     • Cheap and Easy to install
     • Only suitable for small networks
     • Damage to the wire results in catastrophic failure
   • Ring
     • Number of computers does not affect speed
     • One faulty cable or faulty computer will result in catastrophic failure
     • More difficult to add new computers
     • No collisions, as each cable only has one computer able to transmit on it.
   • Mesh
     • Zero catastrophic failure – there are always alternative paths for data
     • Multiple transmissions can happen simultaneously
     • Expensive and Difficult to maintain and administer
     • Redundancy - Lots of unnecessary connections
   • Star
     • Failure of hub/switch is catastrophic and difficult/expensive to fix
     • Easy to add new comptuers
     • Expensive (requires hub/switch and lots of cabling)
     • No collisions Failure of a cable or computer is not catastrophic

3. LAN

   • A Local Area Network (LAN) is a network confined to one location or organisation

4. WAN

   • A Wide Area Network (WAN) is a network of LANs spanning a wide area

5. Packet Switching

   • Multiple transmissions can happen simultaneously
   • Lag is needed to allow several packets to arrive before reading, as the first packet sent may not be the first packet received
   • Large transmissions don’t clog the network