Circuit switching is a method of implementing a telecommunications network in which a dedicated physical communication path is established between two nodes (e.g., two people on a phone call) for the duration of their conversation. This path remains exclusive and is reserved for the use of these two nodes until the connection is terminated.
Here are some key aspects of circuit switching:
1. Establishment of Connection:
- Path Setup: Before communication can occur, a connection must be established by setting up a physical path or circuit between the source and destination. This process involves the selection of a set of intermediate nodes and communication links to form a complete path from source to destination.
- Resource Reservation: Resources such as bandwidth are reserved on each link in the path to ensure that the connection has the necessary resources to communicate effectively.
2. Communication:
- Dedicated Path: Once the path is established, the nodes can communicate over the dedicated path.
- Consistent Bandwidth and Latency: The dedicated nature of the circuit ensures consistent bandwidth and latency for the duration of the connection, which can be critical for certain types of communication like phone calls.
3. Termination:
- Path Teardown: After the communication is complete, the path is torn down, and the reserved resources are released back to the system.
4. Characteristics:
- Efficiency: Circuit switching can be inefficient as resources are reserved exclusively, whether or not they are being used at every moment. This contrasts with packet switching where resources are shared dynamically.
- Delay: There’s an initial delay while the path is being set up, but once the circuit is established, data can be transmitted with very low and predictable delay.
- Reliability: It tends to be reliable for the duration of the connection as the dedicated resources prevent contention and interference from other connections.
5. Use Cases:
- Telephony: Traditional telephone networks are the most common example of circuit switching. When a call is made, a circuit is established, and it remains active until one of the parties hangs up.
- ISDN (Integrated Services Digital Network): This service also uses circuit switching to establish connections for voice and data communications.
6. Comparison with Packet Switching:
- Packet Switching: Unlike circuit switching, packet switching divides data into packets and each packet is routed independently through the network. Packet switching is more efficient and better suited for intermittent or bursty data transfers.
- Hybrid Systems: Some modern networks use a hybrid approach combining aspects of both circuit and packet switching to achieve a balance of efficiency and performance.
7. Historical Significance:
- Circuit switching has been foundational in the development and growth of telecommunication networks. However, with the rise of digital communication and the Internet, packet switching has become more prevalent due to its efficiency and flexibility, especially in the domain of data transmission.
Circuit switching represents a traditional, reliable method of establishing communications, particularly in voice telephony, but it has given way to more modern methods like packet switching in many areas of telecommunications.