Difference between Circuit Switching and Packet Switching

What is Circuit Switching?

Circuit switching was designed in 1878 to send telephone calls down a dedicated channel. It is a method that is used when a dedicated channel or circuit needs to be established.

A channel used in circuit switching is kept reserved and applied only when the two users need to communicate.

Circuit switching connections are classified into two categories half-duplex or full-duplex. Half-duplex communications can be allocated just one channel, while full-duplex interfaces can be assigned two channels.

What is Packet Switching?

Packet switching is a method of grouping data that is transmitted over a digital network into packets. It is a connectionless network switching method. It never establishes any physical connection before the transmission starts. In the packet switching method, before the message is transmitted, it is divided into some manageable parts known as packets.

In this method, each packet divided into two parts: a header and a payload. The header contains the addressing information of the packet. The payload contains the actual message.

Circuit Switching vs Packet Switching – Difference Between Them

Here are the main differences between Circuit Switching and Packet Switching:

Circuit – Switching	Packet – Switching
Circuit switching is a method that is used when a dedicated channel or circuit needs to be established.	Packet switching is a method of grouping data which is transmitted over a digital network into packets.
Circuit switching connections are classified into two categories half-duplex or full-duplex.	Packet Switching is a connectionless network switching method.
You need to establish a dedicated path between the source and the destination before the transfer of data commences.	You do not need to establish a dedicated path from the source to the destination.
It was initially designed for voice transfer.	It was initially designed for data transfer.
It is implemented at Physical Layer.	It is implemented at Network Layer.
In-Circuit switching, data is processed and transmitted at the source only.	In packet switching, data is processed and transmitted, not only at the source but also at the destination.
Its initial cost is low.	Packet switching demands high installation costs.
The protocols for delivery are simpler.	It requires complex protocols for delivery.
Charging happens per minute.	Charging happens per packet.
Each packet follows the same route.	Each packet does not follow the same route.
It does not store and forward transmission.	It does store and forward transmission.
Initially designed for Voice communication.	Initially designed for Data Transmission.
It is an inflexible method because once a path is set, all parts of a transmission follow the same path.	It is a flexible method because the route is created for each packet to travel to the destination.
The message is received in the order, which is sent from the source.	In, packet switching message are received out of order, which is assembled at the destination.
Reserve the entire Bandwidth in advance.	Never reserves the Bandwidth.
You can achieve Circuit switching using two technologies 1) Time or 2) Space Division Switching.	Packet Switching has Datagram Virtual Circuit Approach.

KEY Comparisons table: Circuit Switching and Packet Switching

Item	Circuit-switched	Packet-switched
Bandwidth available	Fixed	No
Dedicated “copper” path	Yes	Dynamic
When can congestion occur	At setup time	On every packet
Possibly wasted bandwidth	Yes	Yes
Store-and-forward transmission	No	No
Each packet follows the same route	Yes	Not necessary
Call setup	Required	Not required
Charging	Per minute	Per packet

Example of Circuit Switching

The given diagram shows how the circuit established between two telephones connected by circuit switch connection. The boxes represent the switching offices and their connection with another telephone office. The blue line represents a connection between both the offices.

Whenever a connection is requested, the links can be established within the switching office, denoted by circles. It has a dedicated circuit established between the communication parties. These links remain as long as communication remains.

Example of Packet Switching

All the packets are sent with a ‘header address’ which tells it where its final destination is, so it knows where to go.

The header address also illustrates the sequence for reassembly at the destination computer so that the packets are rearrange into the correct order.

In this method, one packet also contains details of how many packets should be arriving so that the recipient computer knows if any packet has failed to turn up.

In case if a packet fails to arrive, the recipient computer sends a message back to the sender’s computer, asking for the missing packet to be resent.

The Advantages of Circuit Switching

Here, are pros/benefits of Circuit Switching:

• You will get the full Bandwidth for the duration of the call.
• It reduces the amount of delay the user experiences before and during a call.
• Circuit switching the call will be established with consistent channels, bandwidth, and an ongoing data rate.
• Under circuit switching, the call should be provided with logical channels, Bandwidth, and an ongoing data rate.
• A dedicated path/circuit provides guaranteed data delivery.

Advantages of Packet Switching

Here, are pros/benefits of Packet Switching method:

• This method helps devices of different speeds to communicate with each other.
• High data transmission.
• Helps you to Instantly establish a connection.
• Independent travel
• Delay in delivery of packets is less as packets are sent as soon as they are available.
• Switching devices do not need any massive storage.
• Data delivery can be continued even if some parts of the network faces link failure issues.
• It provides simultaneous usage of the same channel with the help of multiple users.

Disadvantages of Circuit Switching

Here, are some cons/drawbacks of circuit switching method:

• It takes a longer time to set up the circuit.
• During a disaster or crisis, the network may become unstable or unavailable.
• Dedicating one channel to a single usage makes it unavailable to other services.
• It requires more Bandwidth.
• In this kind of circuit switching method, both ends must operate at the same rate during the entire connection.
• It provides an entire channel to one service and one individual path.

Disadvantages of Packet Switching

Here, are some cons/drawbacks of Packet Switching method:

• Under heavy use, there can be a significant delay in the process.
• Packet switching depends on a range of complex protocols that much be managed from deployment.
• Data packets may become corrupted or lost.
• Protocols are needed for a reliable transfer.
• Packet switching only provide a voice call experience that may result in choppy audio, making it is tough for the users to understand each other.
• It helps you to reduce costs in a number of ways.