Datagram

A datagram is a self-contained packet of computer-readable information that uses the more common means of packet switching in networks of many interconnected media: routing, as opposed to virtual circuit packet switching. Datagram routing allow new paths to be decided on a per-packet basis, although this rarely happens. Virtual circuits either need predefined failover mechanisms, as in Multi-Protocol Label Switching, or, like a telephone call, the virtual circuit must be created again and reserve resources before the conversation can continue.

Internet Protocol version 4 and Internet Protocol version 6 packets are datagrams.