There are a number of differences between Virtual circuits and Datagram networks. Virtual Circuits are computer networks that provide connection-oriented services, while those providing connection-less services are called as Datagram networks.
Examples: The Internet which we use is based on Datagram network. ATM (Asynchronous Transfer Mode) and frame relay – are virtual circuit networks and, therefore they use connections at the network layer.
Differences between Virtual Circuits and Datagram Networks
| Virtual Circuits | Datagram Networks |
|---|---|
| Virtual circuits are connection-oriented, which means that there is a reservation of resources like buffers, bandwidth, etc. for the time during which the newly setup VC is going to be used by a data transfer session. | It is connectionless service. There is no need for reservation of resources as there is no dedicated path for a connection session. |
| A virtual circuit network uses a fixed path for a particular session, after which it breaks the connection and another path has to be set up for the next the next session. | A Datagram based network is a true packet switched network. There is no fixed path for transmitting data. |
| All the packets follow the same path and hence a global header is required only for the first packet of connection and other packets will not require it. | Every packet is free to choose any path, and hence all the packets must be associated with a header containing information about the source and the upper layer data. |
| Packets reach in order to the destination as data follows the same path. | Data packets reach the destination in random order, which means they need not reach in the order in which they were sent out. |
| Virtual Circuits are highly reliable. | Datagram networks are not as reliable as Virtual Circuits. |
| Implementation of virtual circuits is costly as each time a new connection has to be set up with reservation of resources and extra information handling at routers. | But it is always easy and cost-efficient to implement datagram networks as there is no need of reserving resources and making a dedicated path each time an application has to communicate. |
