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Difference Between Circuit Switching and Packet Switching

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Last updated date: 22nd Jul 2024
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Introduction of Circuit Switching and Packet Switching

Switching is a mechanism to connect different networks or different components of a network. Circuit switching and packet switching are two different kinds of switching. For data transfer through circuit switching, a dedicated path is employed between the source and the destination. However, packet switching is a connectionless technique. Initially, the circuit switching technique was designed for voice communication and the packet switching technique was designed for data transfer. Generally, the packet switching method is far more efficient than the circuit switching method. These two techniques have interesting differences, which will be discussed below. 


Circuit Switching

Circuit switching is a method of switching, which uses a dedicated connection between the sender and the receiver for data transfer. There are three phases of circuit switching, which are as follows:

  1. Circuit Establishment: A dedicated physical route is established between the sender and the receiver. The path may include a number of intermediate switching centers.

  2. Transfer of Data: After the establishment or setup phase, data is transferred through the dedicated path.

  3. Circuit Disconnect: Once the data transfer is done, the circuit is disconnected from one of the ends. All the intermediate links are disconnected in this phase. Circuit switching is usually used in telephones.


To explain the circuit switch, let’s try an example of a telephone network. If a call is dialed from one telephone to another, switches of the telephone exchange make a wire circuit that is continuous between those two telephones, as long as the call goes. During a connection in a circuit network, a small delay is permanent. The competing users cannot degrade any circuit, because till the release of the circuit and setting up a new connection, it gets protected from use by the other callers. When there is a situation in which no communication is actually happening, the channel still stands reserved and gets protection from competing users. 


Packet Switching

In the packet switching method, the data is broken into “pieces” or “packets” and transmitted individually from the source to the destination. Upon receiving, the packets are reassembled at the destination. This method does not require any pre-established dedicated route. The types of packet switching are:

  • Virtual Circuit Based Packet Switching: In this mode of packet switching, virtual circuits are established for each packet. Each packet is transmitted through the predestined route. This mode has similar phases as the circuit switching method.

  • Datagram Based Packet Switching: In this mode, every packet has two parts, which are a header and a payload. The header of a packet contains the required information (e.g. source and destination addresses, port identity, etc.). The payload contains the original data. The packets are transmitted randomly without any predestined path. At the receiver end, all the packets are arranged and assembled, based on the header information. 


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History of Packet Switching Method

In the 1960s, Paul Baran at RAND corporation, USA, first independently explored the concept of switching data of small blocks while in the UK, in 1965, Donald Davies explored this concept at National Physical Laboratory (NPL). The Air Force of the US in the late 1950s, created a network of wide areas for the semi-automatic ground environment (SAGE) radar defense system. There were vulnerabilities in the network after being recognised by the Air Force, soughted a new system that could survive a nuclear attack and enable a response. The attractiveness of first strike by the enemies diminishes because of this system. To support the initiative taken by the Air Force, Baran created the concept of distributed adaptive message block switching. The Air Force first saw the concept in the summer of 1961, as b-265. It was published later in 1964 as RAND report p-2626. A basic architecture for a communication network that is large-scale, distributed and survivable was described in the p-2626 report. 


It focuses on three main points; making a use of a network that is decentralized with many paths in between the two points, it focuses on dividing the messages of the users into message blocks and lastly, the messages are delivered by forward and store stitching. 


Uses of Packet Switching in Network

Packet switching optimizes using the channel capacity that is available in digital networks of telecommunications, like computer networks, it increases communication’s robustness and it decreases the transmission latency.


It is mostly used in local area networks and on the internet. The internet protocol suite used a variety of link layer technologies to implement the internet. Frame relay and Ethernet are common examples. Mobile phone technologies which are new, use packet switching.


Comparison between Circuit Switching and Packet Switching

The comparison between circuit switching and packet switching is shown in the following table:


Circuit Switching vs Packet Switching


Comparing Factor

Circuit Switching

Packet Switching 

Connection

A dedicated connection is required. 

It is a Connectionless method.

Process 

Data is transferred in three phases. At first, a dedicated route is established between the source and the destination. Then, the data is transmitted and after that, the circuit is disconnected.

The data is broken into packets of variable lengths, each of them containing a header (carries addresses) and a payload (carries actual data). The packets are transmitted randomly and assembled at the destination.

Flexibility 

The circuit route is inflexible. 

The routes for the packets are flexible. 

Data processing 

The data is processed at the source end.

The data is processed at nodes and the source.

Usage 

Usually used for voice communication.

Used for data communication.

Modes 

Time-division switching and space division switching.

Virtual circuit switching and datagram switching.

Implementation 

Implemented at physical layers.

Implemented at network works.

Advantages 

Effective for continuous and long transmission. The dedicated path ensures steady communication.

Delay in communication is less. Due to the flexible routes, the method is almost immune to network failures. This method has better bandwidth coverage.

Disadvantages 

The inflexible route cannot be used for multiple data transmission. Bandwidth requirement is very high.

High installation charge and complex structure. 


Did you know?

  • Apart from circuit switching and packet switching, there is a third type of switching namely message switching. This is a connectionless technique, where an entire message is routed from the source to the destination, through a number of intermediate nodes. Each node stores the data and then forwards it to the next node.

  • Packet switching is derived from the message switching technique.

  • The concept of packet switching was invented by Paul Baran.

  • Circuit switching is effective for voice transmission and packet switching is effective for data transmission.

FAQs on Difference Between Circuit Switching and Packet Switching

1.What is circuit switching and packet switching? What are the differences?

Circuit switching is a switching method that uses dedicated physical routes between the sender and the receiver. The process is carried out in three phases. At first, the physical route is established, followed by the data transmission. At last, the path is disconnected from any of the ends. Circuit switching is generally used for voice transmission. Packet switching is a connectionless switching technique. The data is broken into packets or units, which are transmitted to the destination via individual routes. The routes are flexible. Each packet consists of two parts: header and payload. The header carries the information regarding the source and destination addresses whereas the payload carries the original data. Packet switching is effectively used in data communication.

2. Write down the difference between message switching and packet switching.

In the message switching method, only one datagram (message) is transmitted to the destination. The message hops through intermediate stations. Each station stores and then forwards the data. In the packet switching technique, multiple packets of data are generated. The packets are sent to the destination via flexible routes, depending on their header information.

3. Write about the history of packet-switched networks?

Packet switching’s research started at National physical Laboratory (NPL) in 1965, proposing a wide-area network and in 1966, a local-area network. The funding of ARPANET was given a surety by Bob Taylor and it’s planning began in 1967 after Larry Roberts was hired by him. AppleTalk- it is a proprietary suite development by Apple in 1985 of networking protocols for Apple Macintosh computers. The ARPANET is one of the first networks and was the internet's progenitor network with ARPA’s SATNET, which runs the TCP/IP suite by using packet switching technologies. 

4. Write about the alternatives of circuit switching?

There is a contrast of circuit switching with packet switching and message switching. Messages in message switching routes at one go, entirely from one hop at one time, it means it stores and forwards the entire message. The data that has to be transmitted into packets through a network independently gets divided by packet switching. Packet switching can be a communication which is connection-less or it can be a connection-oriented communication. It is totally based on data grams or virtual circuits. In virtual circuits, connections are formed even before the transfer of any packets and they deliver it in order. It also uses a packet switching method. 

5. Differentiate between connection-less and connection-oriented packet switching?

Connectionless packet switching is also termed as datagram switching while connection-oriented packet switching is termed as virtual circuit switching. In connectionless mode, every packet has a label stating the address of the destination, the address of the source and port numbers.


In connection-oriented mode, a set-up phase is essential for the establishment of the parameters of the communication before transferring any packet. The signalling protocol that is used for the set-up, allows the application to tell its requirements and to discover link parameters. To understand better, search the study material Physics Revision Notes for Class 11 provided by Vedantu.