Datagram and Virtual circuit | Loksewa 078 Question Paper

 Q.  Define and compare Datagram and Virtual Circuit network with diagram. (10 marks)

answer:

A datagram is a basic transfer unit associated with a packet-switched network while  virtual circuit network is a category of packet switching network, where a virtual path is established between the source and the destination systems for data communication to occur.

The comparison between the Datagram and Virtual Circuit network is mentioned below:

Virtual Circuits Networks	Datagram Networks
These are connection oriented networks.	These networks are connectionless.
Virtual Circuit is the connection oriented service in which there is a implementation of resources like buffers, CPU, bandwidth, etc., used by virtual circuit for a data transfer session.	On other hand Datagram is the connection less service where no such resources are required for the data transmission.
Each packet contains a short VC number State information in the virtual circuit.	Each packet contains the full source and destination address in the datagram
In virtual circuit subnet, a route chosen when VC is set up; all packets follow it.	In datagram subnet, each packet is routed independently
Virtual circuits are more expensive in terms of installation and maintenance	Datagram networks are much cheaper to install and maintain.
In Virtual circuit, all packets follow a specific path.	In datagram, all packets are free to use any available path
Congestion control is easy if enough resources can be allocated in advance for each Virtual circuit.	Congestion control is difficult in the datagram
Virtual Circuits are implemented in networks using Asynchronous Transfer Mode (ATM) communications, as in making telephone calls.	Datagram communication is generally guided by User Datagram Protocol (UDP). They are applied in IP network.