Connections and connectionless data transmission

The complementary concepts of connection-mode data transfer and connectionless data transmission are the fundamental models of communication in the architecture of Open Systems Interconnection (OSI). As the names imply, connection-mode data transfer involves the establishment and maintenance of a connection, which represents a dynamically negotiated agreement concerning the transfer of a series of related units of data; connectionless data transmission relies only on the prior knowledge that peer entities have of each other to transmit independent, unrelated data units, and does not involve the establishment of a connection. The two concepts together describe all of the peer-to-peer interactions that take place in the OSI environment. The national and international organizations concerned with OSI have applied these concepts successfully in the development of OSI service and protocol standards.