Datagram

A datagram is a packet of data that constitutes the smallest block of information in a datagram-switched network, which is one of two types of packet-switched communication protocols used to routing said units of information between nodes of a network through various routes, which is why it is said that it is not connection-oriented. The alternative to this packet switching is the connection-oriented virtual circuit.

Model structure

Datagrams are made up of:

• One head with control information
• own data to be transmitted.

Operation

In the datagram technique, each packet is treated independently thanks to the fact that it can contain the source and recipient addresses in the header. Through a router, also known as a router or, more popularly, router, the network can route each fragment towards the receiver or DTE (Data Terminal Equipment) by different routes.

This operation is the essential difference with virtual circuit switching and determines its strengths and weaknesses, which also condition its suitability to the type of network application.

Advantages and disadvantages

This flexibility allows:

• traffic control for take advantage of the channel capacity of each network section,
• adapt to congestions and falls of intermediate nodes, avoiding blockages
• lower costswhen you can adjust the bandwidth and number of specified lines.

However, this technique also makes it impossible to guarantee:

• constant speed of data flow,
• that each package is received in original order,
• that all reach their destination.

For all these reasons, it depends on new procedures to reconstruct the information properly at the destination. In addition, it increases the volume of traffic a bit, by repeating header information such as the address to each frame.

Internet use

Because the internet is a packet-switched network, it has protocols:

• connection-orientedwhere the protocol applied to transport packages is TCPEnglish Transmission Control Protocol ("Transmission Control Protocol"), which ensures that all packages arrive correctly and in order,
• non-connectedwhere the protocol applied is UDPEnglish User Datagram Protocol ("user datagram protocol"), which does not guarantee the delivery of the datagrams and, however, this UDP property is precisely the one that makes the protocols so interesting SNMPEnglish Simple Network Management Protocol ("easy network management protocol"), due to little loading of the network and its absolute independence from the hardware that facilitates the exchange of information.

Datagrams have a place in connectionless network services. IP datagrams are the main units of information on the Internet. The terms frame, message, network packet, and segment are also used to describe the groupings of logical information at the various layers of the OSI Reference Model and in various technology circles.

Examples

• UDP, one of the internet protocols.
• IPX/SPX, from the manufacturer Novell Netware.