In this article, we will discuss what is switching?, types of switching techniques: Circuit Switching, Message Switching, Packet Switching, and also discuss the difference between circuit, message, and packet switching.
What is Switching?
Switching is the mechanism in computer networks that helps in deciding the best route for data transmission if there are multiple paths in a larger network.
Larger networks may have multiple routes to link the sender and receiver. So whenever we send any information between the sender and receiver then the information switches through multiple routes.
Whenever we send information from one device to another, that information does not directly reach that device, there are many intermediate nodes in the middle, and the information switch through these nodes.
Types of Switching Techniques
- Circuit Switching
- Message Switching
- Packet Switching
In-Circuit Switching, a dedicated channel is established for a single connection where the sender and receiver can communicate during the communication session.
In-Circuit Switching, whenever a device communicates with another device, a dedicated communication path (circuit) is established in them over the network.
It is a switching technique that creates a pre-specific route between the sender and receiver and this route is reserved for both these devices as long as the connection is active. Both devices are connected through this specific route and data transfer can also be done only through this specific route. Other devices cannot use this specific route for data transmission because this specific route is reserved.
This type of network switching was designed and used in the early analog telephone network. We used circuit switching to physically connect devices in the telephone network.
Communication that takes place through circuit switching has 3 phases:
- Establish a circuit: In the first phase, a circuit is established means a dedicated link is established between the sender and the receiver through a number of switching centers or nodes.
- Transfer the data: Once the circuit is established, means the connection is established between the sender and receiver, they can communicate with each other.
- Disconnect the circuit: Once the communication is completed between the sender and receiver, the circuit disconnects. The circuit disconnection is done by one of the users i.e. the sender or the receiver.
Simple Example of Telephone Network: First we call the other user, once he receives the call, the connection is established and both can communicate with each other, after if one of the users disconnects the phone, the circuit disconnects.
Advantages of Circuit Switching
- A dedicated link is established between both devices which provides a guaranteed data transmission.
- Once the connection is established between the sender and receiver, data can be transmitted without any delay because they are directly connected so no waiting time at each switch.
- A dedicated continuous data transmission path is established between the sender and receiver so this switching method is suitable only for long continuous transmission.
Disadvantages of Circuit Switching
- The main disadvantage of this switching method is that once a dedicated path is established then this path becomes reserved and other devices cannot use this path.
- This method does not properly utilize system resources as resources are allocated for the entire duration, these are not available to other connections.
- A dedicated continuous data transmission channel requires more bandwidth.
- Before actual data transfer, a dedicated path has to be established, it takes a long time to establish the path.
There is no dedicated path established between the sender and receiver in message switching, as in circuit switching.
For sending the message, there are many intermediary messages switching nodes which are responsible for transferring the message, and the message is transmitted as a whole from source node-to-destination node.
In Message Switching, when the source node sends a message, the destination address is appended to the message. So in message switching, there is no need to establish a dedicated path between two communication nodes.
When a sender sends a message, the message sends as a whole to the next message switching node, store it in its entirety on the disk, and then transmit the whole message to the next switching node and so on, until the message reaches the destination.
If the next message switching node does not have enough space to store the message, the previous switching node has to waits. When the next node has enough space to store the message, then the previous forwards the message to the next node. That’s why this type of network also called a store-and-forward network.
This technique is not recommended for real-time applications like video and voice, etc.
In packet switching, when we send a message, then the whole message is divided into smaller pieces called packets. These pieces or packets travel across the network and take the shortest path as possible.
Every packet has a sequence number to identify their order at the receiving end.
Each packet contains some information includes a source address, a destination address, intermediate node address information, sequence number, etc. so that individual packets can be routed through the internetwork independently.
Difference between Circuit Switching, Message Switching and Packet Switching
|Circuit Switching||Message Switching||Packet Switching|
|There is physical connection b/w transmitter and receiver||No physical path is set in advance b/w transmitter and receiver||No physical path is established b/w transmitter and receiver|
|All the packet uses same path||Packet are stored and forward||Packet travels independently|
|Need an end to end path before the data transmission||No need of end to end path before data transmission||No need of end to end path before data transmission|
|Reserves the entire bandwidth in advance||Does not reserve the bandwidth in advance||Does not reserve the bandwidth in advance|
|Waste of bandwidth is possible||No waste of bandwidth||No waste of bandwidth|
|It cannot support store and forward transmission||It support store and forward transmission||It support store and forward transmission|
|Not suitable for handling interactive traffic||Suitable for handling interactive traffic||Suitable for handling interactive traffic|
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