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Circuit Switching in Computer Networks

Last Updated on March 14, 2023 by Prepbytes

Circuit Switching is considered one of the earliest technology used for network communication. This technique of Circuit Switching has been widely used in the implementation the telephone networks. Although with the invention of packet switching, its use become less prevalent, still it is used in several specialized applications. In this article, we will discuss circuit switching in detail, including its advantages, disadvantages, and some of its real-world applications.

What is Circuit Switching?

Circuit switching is a network communication method where a dedicated communication path, also known as a circuit, is established between two network nodes before communication can take place. In circuit switching, the nodes involved in the communication reserve the necessary network resources (such as bandwidth and buffers) before any data is transmitted. Once the circuit is established, data is transmitted over the circuit in a continuous stream until the communication is complete.

The above image depicts the Circuit Switching Diagram. In this diagram, a connection link is established between Terminal 1 and Terminal 6 via Switches 1, 3, 4, and 5.

Phases of Circuit Switching

The communication between sender and receiver using the circuit switching takes place in three steps. The steps are given below:

Step 1: Connection Establishment
A dedicated network is established between the source and the destination with the help of several intermediate switching centers. When the transmitter and receiver transfer signals across the circuit, they can request and receive communication signals.

Step 2: Transfer of Data
When the circuit is established, data and speech signals may be sent between the source and the destination. The link between the two ends persists as long as they communicate.

Step 3: Circuit Disconnection
The circuit is disconnected when one of the users requests the disconnect. When a connection is disconnected, all intermediary linkages between the sender and the receiver are terminated.

Advantages of Circuit Switching

The advantages of Circuit Switching are:

  • Predictable Performance: One of the primary benefits of circuit switching is its predictable performance. Because network resources are allocated for the duration of the connection, there is no conflict for these resources among nodes. This means that both the data transmission rate and the delay are consistent and predictable.
  • Efficient use of resources: In terms of resource utilization, circuit switching outweighs packet switching. Because the resources are reserved for the duration of the transmission, even if there are periods of inactivity, this is the case. As a consequence, there is no resource waste.
  • Guaranteed Quality of Service: Because the resources are allocated for the duration of the connection, circuit switching delivers assured quality of service (QoS). This means that the data transmission rate and latency are constant and predictable, and no data loss due to congestion exists.

Disadvantages of Circuit Switching

Circuit switching has significant drawbacks as well. These are as follows:

  • High Connection Establishment Time: After the dedicated path is created, the only delay is in the rate of data transfer.
  • No Data Transmission while establishing the connection: It takes around 10 seconds to establish a connection during which no data may be transferred.
  • Expensive: Because each connection requires a dedicated route, it is more costly than other switching strategies.
  • Wastage of Resources: It is inefficient to use since once the connection is established and no data is exchanged, the capacity of the path is wasted.

Since the connection is reserved in the circuit Switching, no additional data may be sent even if the channel is free.

Real-world Applications of Circuit Switching

Circuit Switching has the following real-world Applications:

  • Telephone networks: Circuit switching was developed for use in telephone networks, where it is still used today. Before any communication can take place in a telephone network, a dedicated circuit must be established between two nodes. This circuit is operational for the duration of the call.
  • Video Conferencing: Circuit switching is also used in video conferencing systems. A dedicated connection is established between the conference nodes in this application. This ensures that the data transmission rate and latency are stable and predictable, resulting in a high-quality video conferencing experience..
  • Satellite Communications: Circuit switching is used in satellite communications to establish a communication link between the satellite and the ground station via a dedicated circuit. This guarantees a steady and trustworthy communication route, which is crucial for remote sensing and weather forecasting applications.

Circuit switching is a network communication method that was widely used in telephone networks and is still used in some specific applications today. While circuit switching provides predictable performance and guaranteed quality of service, it can be inefficient in terms of resource utilization and has a slow setup time. As a result, it is not very scalable and is not suitable for all applications.

Frequently Asked Questions (FAQs)

Some Frequently Asked Questions on Circuit Switching in Computer Networks are given below.

Ques 1. Is circuit switching scalable?
Ans. No, circuit switching is not scalable, as the number of circuits that can be established is limited by the capacity of the network.

Ques 2. What happens if a circuit fails in circuit switching?
Ans. A single failure in the circuit can disrupt the entire communication session.

Ques 3. Is circuit switching still used today?
Ans. Circuit switching is still used today, particularly for voice communications in certain applications such as traditional telephone networks. However, it has largely been replaced by packet switching for data communications.

Ques 4. What is the difference between circuit switching and packet switching?
Ans. Circuit switching establishes a dedicated communication path before data transmission, while packet switching sends data in discrete packets without a dedicated communication path.

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