Datagram

The idea behind datagram

The idea behind datagrams is incredibly simple: You just include in every packet enough information to enable any switch to decide how to get it to its destination. That is, every packet contains the complete destination address.

Contactless

A host can send a packet anywhere at any time, since any packet that turns up at a switch can be immediately forwarded (assuming a correctly populated forwarding table). For this reason, datagram networks are often called connectionless

Virtual Circuit Switching

Not popular today, just ignore it.