What is virtual circuit packet switching?

Packet Switched service transfers the data from source to destination. Data is transferred on a type of network in which small units of data called packets are transferred. Each packet contains a destination address within it, where it has to be received.

This type of communication between receiver & sender is connectionless. The internet is also a connectionless network. Most of the traffic over the internet uses packet switched service.

Voice call over the internet is a type of packet switching, where each end of the conversation is divided into small packets & is reassembled later into a complete message. Packets are made up of a header and a payload, header directs it to the destination & data in the payload is the actual data which is to be transferred.

Types of Packet Switching Network

The packet switching network is of two types −

  • Datagram packet switching

  • Virtual circuit packet switching

The packet switching network is diagrammatically represented as follows −

Virtual circuit switching

It is a network where a virtual connection is established between source and the destination. Through this network, packets will be transferred during any call. The path established between two points appears as a dedicated physical circuit. Therefore, it is called a virtual circuit. It is a type of packet switching.

It is a connection-oriented service, where the first packet goes and reserves the resources for the subsequent packets.

For examples − X.25 and frame relay.

The pictorial representation of virtual circuit connection over a telephone call is as follows −

Let’s try to understand the concept with the help of data flow diagram as shown below −


Step 1 − Sender A establishes a call request connection to connect with the receiver.

Step 2 − Receiver B establishes a call accepting connection to connect with sender.

Step 3 − Data will be transferred whenever the router is established.

Step 4 − Node 1 and Node 2 are intermediate nodes between sender and receiver, the data will be transferred by connecting two nodes virtually.

Step 5 − After transmitting the data, an ACK will be sent by the receiver by saying a message is received.

Step 6 − A clear signal will be sent if the user wants to terminate the connection.


The advantages of virtual circuit are as follows −

  • Packets are delivered in the same order as they all follow the same route between the source & the destination.

  • The overhead is smaller as full address is not required on each packet as they all follow the same established path.

  • The connection is more reliable as it is one to one connection.

  • Less chances of data loss.


The disadvantages of virtual circuit are as follows −

  • The switching equipment should be powerful.

  • Re-establishment of the network is difficult as if there is any failure. All calls need to be re-established.

Updated on: 11-Sep-2021

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