What Is Circuit Switching?

In a large network, many ways and routes send and receive information and data from sender to receiver. So, the switching techniques will decide which route is the best for a specific transmission. one of the techniques is circuit switching which we are going to discuss in this blog. Switching techniques are in use to connect the systems for one-to-one communication. So, In this blog, we will understand how these switches affect the transfer of data from sender to receiver. There are many types of switching techniques,

• Circuit switching
• Packet switching
• Messaging switching

Circuit switching:

In 1878 circuit switching was designed to send telephone calls on the dedicated channel. The circuit switching method is used when the dedicated channel needs to be established. It is additive into two categories. One is a full duplex and the other a half-duplex. A half duplex is for one channel while a full duplex is specific for two channels. The limitation of circuit switching is its reserved behavior.

However, circuit switching is connection-oriented. It designed a dedicated communication path from the sender to the receiver. A link is set to send and receive data. This link between the sender and receiver is in the physical form. Telephone communication is an example. Bandwidth is fixed in the circuit switching.

Due to the dedicated circuit data loss and chances of error are less but the loss of bandwidth takes place between the sender and receiver. By all means, it is completely transparent.

Types of circuit switching:

There are two types of switching are,

• Space division switch
• Time division switch

Space division switch:

It is the switching technology in which single transmission is completed through a Physical set of cross points. Crossbar switches are mostly utilize in space division switches. It is a metallic semiconductor cross point that can be disabling and able by a unit control. However, the crossbar switch is comprises  of semiconductors, for example, FPGAs Xilinx crossbar. Additionally, the prime advantage of using space division switches is a high speed, non-blocking switches, and a  high capacity. Space division switches are additive in two ways,

• Multistage switch
• Crossbar switch

Crossbar switch:

The crossbar switches are a switch that has input and output lines. The crossbar switches have intersections called Crosspoint.

Cons of crossbar switch:

As the number of stations increased the cross points also increased. Therefore, it will become more expensive. To avoid this problem, use the multistage switch.

Multistage switch:

The multistage switch split the crossbar into smaller units and then interconnects them. Multistage switch reduces the number of cross points. If one path fails then the other paths are available.

Advantages and disadvantages of circuit switching:

Advantages:

• It uses the fixed or full bandwidth for the call duration.
• It is suitable for long and continuous communication.
• No time is wasted while switching.
• A dedicated channel is used it increases the quality of communication.
• Most important the rate is fixed at which data is transfers.
• A dedicated circuit gives a guarantee for data delivery.

Disadvantages:

• More bandwidth is need because dedicated channels are used.
• The resources are not fully in use.
• A dedicated circuit is almost impossible to transfer other data even if the channels are free.
• For the establishment of a physical layer, the time used by the two stations is too long.
• It is very expensive.
• circuit switching is set for each connection.
• The physical link is keep up even if there is no data in use until the user terminates the link.
• In the circuit switching method, both ends must operate at the same rate during the whole connection.
• The network may be unstable during the crisis.

Example of circuit switching:

The diagram shows how the circuit is set between telephones. Telephones are link by a circuit switch connection. Switches and their connection with other telephone boxes are shown by the boxes. While the blue lines indicate the connection between offices.

Circles indicate that a link is official in the switching office. Between the communication groups, a dedicated link is set. The link remains as long as communication between parties remains.

Where circuit switching is used for?

Here below are examples where circuit switching is used for.

• Dial-up network connections:

When a computer connects to the internet through a dial-up service it uses the public switched network. In an Internet protocol, data packets is transfer over a telephone network.

• Optical circuit:

Circuit switching is also in work at a data center. In order, to meet the bandwidth requirements and traditional data centers use optical circuit switching.

• Continuous connections:

It is going to use for the links for a long period. For example, long-distance communication. Traditional telephone systems such as landlines use circuit switching for continuous connection.

Phases of circuit switching:

Circuit switching are three main phases are,

• Connection establishment:

Connection establishments are also called call setups. In this phase, the connection is in working between two endpoints for communication. The sender and receiver send information back and forth via this connection. Usually called intermediate links between two parties.

• Transfer data:

Data is transfer from the source to the destination. The connections remain for the length of interaction.

• Connection disablement:

It is also called the teardown phase. At the end of intersections. One endpoint sends a message for disconnection. The communication routes along with intermediate links are terminated.

The most common example of circuit switching is the telephone system. Time-division multiplexing and frequency division multiplexing are these two methods that multiplex the multiple signals into a single carrier.

Time-division multiplexing:

TDM was responsible for receiving and transmitting an independent signal over a common path utilizing a synchronized switch at each end. It is in work for long-distance communication links. TDM carries heavy data traffic loads from the end user. It can classify into two forms,

Frequency Division Multiplexing:

Frequency division multiplexing is in use when multiple data signals are combined for simultaneous transmission through a shared medium. It is a way in which total bandwidth is divided into a series of sub-bands, where each sub-bands carry a different signal.

Item	Circuit switching
Wasted bandwidth	yes
Bandwidth available	fixed
Call setup	required
charging	Per minute
Store and forward transmission	NO
Designated “copper” path	At setup time

 Frequently asked questions:

Qno1: Is the switching bandwidth of the circuit fixed or variable?

Ans:  In the circuit, the switching bandwidth is fixed.

Qno2: In a traditional telephone system which type of switching is used?

Ans:  circuit switching

Qno3:  Ethernet is the example of which switching?

Answer: Ethernet is an example of packet switching.

Q no4: what is time division switching?

Ans: It is a method to allow several connections to travel along a particular path with multiplexing-based time division. However, it is in use for long-distance communication.

Q no 5: which switching technique controls traffic congestion?

Ans: Congestion, when the network is an overload Packet switching, is more efficient. Therefore, It ensures the maximum utilization of bandwidth of all cables. Packet switching is perfectly capable to reduce congestion.