Analysis of information sources in references of the Wikipedia article "Datagram" in English language version.
three parameters uniquely specify a connection between source and destination Hosts." "The destination IMP returns a positive acknowledgment for receipt of the message to the source IMP, which in turn passes this acknowledgment to the source Host." "Each link is unidirectional and is controlled by the network so that no more than one message at a time may be sent over it.
Arpanet had its deficiencies, however, for it was neither a true datagram network nor did it provide end-to-end error correction.
Arpanet was virtual circuit." "essentially a virtual circuit service using internal datagram