Data Transmission: Circuit Switching vs Packet Switching

Data Transmission Modes

• Circuit switching: a path is set up between the sender and receiver before transmission, and all data follows the same path, in order.
• Circuit switching: the path cannot be used by any other data during transmission.

Packet Switching

• Data is split into packets before transmission.
• Each packet may be transmitted by different routes through the network.
• Packets may arrive out of order and are reassembled on arrival.
• Advantages of packet switching:
  • Better security as it is very difficult to intercept and reconstruct packets.
  • Makes more efficient use of data lines as there is no waiting during gaps.
  • Less likely to be affected by network failure because multiple paths are used.

Switching in a Computer Network

• Switching sends data along the appropriate path.
• Switching prevents all the data being sent to all parts of the network.
• It requires less bandwidth and is more efficient not to send data where it is not required.

Serial and Parallel Transmission

• Serial transmission:
  • Data is sent bit-by-bit along the same data line.
  • Advantages:
    • Requires only two wires compared to 8 or 16 in parallel.
    • Can travel longer distances than parallel.
    • Simpler interface/circuit board.
• Parallel transmission:
  • All bits in a byte are sent simultaneously along separate data lines.
  • Advantage: transmission is faster than serial transmission.

Data Transmission Directions

• Simplex: data transmission is possible in one direction only along a computer network/pathway/cable.
• Half-duplex: data can be sent in either direction, but only in one direction at a time.
• Full-duplex: data can be sent in either direction, in both directions at the same time/simultaneously.

Compare and contrast circuit switching and packet switching in computer networks, highlighting the advantages of packet switching. Practice with past paper questions from Jan 2012.