Communication

Communication

1. Networking

   • Topologies
     • Physical
       • How the devices are physically wired
       • Logical
         • How data is transported around a network
     • Bus
     • Star
   • Network types
     • Client-server
       • Servers store resources which can be requested by clients
         • Better security
         • Network is easier to manage
     • Peer-to-peer
       • Each device is both a client and a server
         • More robust
   • Wireless Networks
     • Collisions
       • Avoided using frequency modulation
         • Either 2.4GHz or 5GHz band
       • CSMA/CA
         • A protocol allowing devices on the same band to communicate
         • RTS/CTS
           • An RTS signal is sent when a channel is clear, and data is not transmitted until a CTS signal is received
     • SSID
       • Allows a WAP to identify which network a packet is from
     • Security
       • Hidden SSID
       • MAC Filtering
       • Wireless Protected Access
         • The only reliable method

2. Speed

   • Latency
     • The delay between the first bit being sent and received
   • Bitrate
     • Directly proportional
   • Baud rate - the number of signal changes per second
   • Bandwidth

3. Type

   • Serial
     • Bits are sent one after another along the same wire
   • Parallel
     • Bits are sent simultaneously across multiple wires
   • Synchronous
     • The sender and receiver are synchronised using a common clock
   • Asynchronous
     • The sender and receiver are synchronised each transmission using a start and stop bit