# Circuit Switching ## What is Circuit Switching Circuit switching is a communication method in which a dedicated communication path or circuit is established between two endpoints before data transmission begins and maintained for the entire duration of the communication session. The traditional telephone network is the classic example of circuit switching. When you make a phone call, a dedicated circuit is established through the telephone network from your phone to the recipient's phone. This circuit is reserved exclusively for your call and cannot be used by anyone else while the call is active. ## How Circuit Switching Works Before communication can begin, a setup phase establishes the circuit. The network allocates dedicated resources including bandwidth along every link in the path from source to destination. These resources remain reserved for the duration of the session even if no data is being transmitted. When the communication ends, the circuit is torn down and the resources are released back to the network for use by other connections. ## Characteristics of Circuit Switching Circuit switching provides a guaranteed quality of service because dedicated bandwidth is reserved throughout the session. The delay is consistent and predictable because the path is fixed and resources are dedicated. There is no sharing of resources with other users, so performance does not degrade based on other users' activity. The connection setup time can be significant before communication can begin. ## Advantages of Circuit Switching Circuit switching is well suited for applications requiring consistent bandwidth and predictable latency such as voice calls. Once the circuit is established, data flows continuously without any routing decisions being made for each piece of data. The performance is stable and does not vary during the session. ## Disadvantages of Circuit Switching Circuit switching wastes bandwidth when one party is not talking during a conversation. The reserved resources cannot be used by anyone else even when idle. The network must have enough capacity to simultaneously handle all active circuits. Setup time is required before communication can begin. Circuit switching does not adapt well to bursty data traffic where large amounts of data are sent briefly followed by silence. ## Circuit Switching vs Packet Switching The telephone network traditionally used circuit switching. The internet uses packet switching. In packet switching data is divided into packets and each packet is routed independently through the network. Resources are not reserved in advance and multiple communications share the same links. Packet switching is far more efficient for data applications but may have variable delay and does not guarantee consistent bandwidth.