This document summarizes circuit switching and packet switching approaches in computer networks. It discusses how circuit switching establishes a dedicated path but wastes bandwidth when no data is being sent. Packet switching breaks messages into packets that are transmitted independently and can make more efficient use of bandwidth. The document also describes protocols like X.25 that were used for packet switched networks and Frame Relay, which was designed to reduce overhead and improve performance compared to X.25.

1. Data and Computer Communications Eighth Edition by William Stallings Lecture slides by Lawrie Brown Chapter 10 – Circuit Switching and Packet Switching

3. Switched Network

6. Public Circuit Switched Network

7. Circuit Establishment

8. Circuit Switch Elements

10. Space Division Switch

11. 3 Stage Space Division Switch

13. Softswitch

14. Traditional Circuit Switching

16. Packet Switching

19. Datagram Diagram

20. Virtual Circuit Diagram

22. Packet Size

24. Event Timing

29. X.25 Use of Virtual Circuits

30. User Data and X.25 Protocol Control Information

34. Protocol Architecture