Circuit switching is one of the techniques involved in switching. In the field of communication and networking, there is a requirement of transmitting data all over the world. To transfer the data the basic step is to find a route. There are multiple ways or we can say paths to transfer the data. To choose the best possible path so that the data can be routed efficiently is defined as Switching. Multiple devices should be connected which can be switched to transmit the data. The connection can be from point to point. But in this situation as the number of devices increases the number of connections will also increase. Another possibility of connection is by keeping the devices to connect at the center. This kind of topology is also referred to as ‘Star Topology’. For the larger networks, these topologies cant be used.
This can be overcome by the Switching technique. There are three types of switching like circuit, packet, and message. From these classifications, circuit and packet switchings are most commonly used. Instead of communication, message switching is preferred in networking. It follows the mechanism of ‘Store and Forward’ for data transmission.
What is Circuit Switching?
The transfer of data can be made possible by establishing the connection between the nodes. This type of switching can be defined as circuit switching. In this type of switching, the data transfer or communication takes place when the dedicated connection is established. It is a three-phase process to proceed with communication.
- Circuit Establishment
- Data Transfer
- Circuit Disconnect
The circuit searches for a possible connection. Once the dedicated path is formed then the data transfer takes place. After the data is transferred, the acknowledgment is sent by the receiver. After the acknowledgment signal, the circuits get disconnected.
The above circuit switching diagram shows that when the data is transmitted from user-1 at the intermediate nodes, then it gets processed. Meanwhile, if the user-2 requests for the channel, the nodes send the acknowledgment as busy. Until the data transmission is done from user-1, then the user-2 will not get access. One of the best suitable examples of the Circuit Switched network is ‘Analog Telephone.’
The main characteristics of a circuit-switched network are as follows:
- It is known as Public Network.
- It is capable of handling the data that is digital and the traffic because of voice signals.
- The connection of the network allows transferring the ‘electrical current’ along with the voice signal.
- It is a ‘Connection-Oriented’ process.
- First, the path is set then the data is transmitted in this type of switching network.
- The fixed amount of data is possibly transferred by circuit switching.
- As the connection is established, the path will not be terminated until the connection gets terminated.
Advantages and Disadvantages
Like other switching circuits Circuit Switching has certain Advantages and Disadvantages based on the path establishment and the transmission of data.
The advantages of circuit switching are
- The dedicated connection leads to the accurate transmission of data.
- There is the allotment of fixed bandwidth and channels for the communication between the sender and receiver. It can be desirable for ‘long Distance Communication’.
- Due to the less measure of delay, it is preferred for real-time ‘Voice services’.
- Voice Communication can become more real because of ‘Higher Sampling Rates’.
- There is no requirement of a header during the transmission of data. Because the transmission depends upon the slots.
The disadvantages of circuit switching are
- It is dedicated for voice transmission and inconvenient for the data transmission.
- As the bandwidth and channels are fixed, it cannot be made available until the circuit established for communication is attributable. This leads to the phenomenon of Call Drops.
- These dedicated channels led to inefficiency in terms of resource usage.
- The time taken for the establishment of the connection will be probably high.
What are the Two Types of Switches used in Circuit Switching?
To perform this type of switching two types of switches are used. They are:
- Space Division Switches
- Time Division switches
The connection established by the usage of a separate set of crosspoints in the single path. These are known as the Crossbar switches. It can be controlled with the help of a control unit. These crossbars are made of ‘ Xilinks’ or ‘FPGA’s’. These possess high capacity, speed and are non-blocking ones.
To increase the number of connections, more Crossbars switches are used. This increase in the number of ‘Crosspoints’ to make the circuit expensive. To overcome this drawback, another switch is included in this type which is known as the Multistage switch. This switch is obtained by splitting the ‘crossbar switch’. This split small points are interconnected in the multiple paths. If one path fails in routing other paths can be chosen.
Distinguish between Circuit and Packet Switching
The differences in the circuit and packet switching are as follows:
The data transfer is possible after the establishment of a dedicated path.
The data transfer is done in the form of packets and it follows dynamic routing.
It is preferred mainly for voice transmission.
It is preferred during data transmission.
It is reliable because the data is transfer takes place from sender to receiver with the establishment of end to end path.
The packets of data possess the address of the Destination and the Source in their Headers. It is a connectionless service.
Because of the dedicated path establishment, this type of switching becomes inflexible.
Dynamic routing involved in this leads to flexible data transmission.
In this switching, the processing of data begins after the path is decided by the system.
In the packet switching each packet is associated with a header. This header consists of the address of the destination the data transfer takes place. The processing of this data takes place at the ‘Intermediate Nodes’.
This switching is implemented at the physical layer.
This packet switching is implemented at the Network layer.
The delay generated remains uniform throughout the transmission.
Because the data is divided into packets and the connectionless service leads to non-uniformity in delay.
Is TCP a Circuit Switching?
TCP is an internet communication protocol. It transmits the data in the form of packets. The formation packets are possible in the ‘Virtual Circuit Model’. This technique is referred to as Packet switching. Hence TCP doesn’t follow circuit switching.
Thus, switching is a priority for data communication worldwide. Each type in it is used as per the requirement in applications. From the above discussion can you judge which one is better either circuit switching or packet switching?