The unreliable datagram service and data-stream service operated essentially identically to UDP and TCP on top of IP.
Louis Pouzin (born 1931 in Chantenay-Saint-Imbert, Nièvre, France) invented the datagram and designed an early packet communications network, CYCLADES.
In theory, under IPv4, time to live is measured in seconds, although every host that passes the datagram must reduce the TTL by at least one unit.