Packets and Circuits

• The Internet is packet-switched, while the telephone networks are circuit-switched

• What’s the difference?

• • Circuit-switching opens a dedicated end-to-end connection between two points
  • • Guaranteed quality of service (bandwidth, latency and jitter)
    • Phone call: 64 Kbps, latency based on speed of light, no jitter
    • No information is lost as long as the circuit is up
  • Packet-switching divides a long message into a number of small “packets” of information (typically <= 1500 bytes)
  • • Each routed independently!
    • No guarantees of quality of service, and packets maybe lost!
    • Much more efficient use of resources
    • Cheaper to develop products