Page "Session layer" Paragraph 30

The TCP / IP reference model does not concern itself with the OSI model's details of application or transport protocol semantics and therefore does not consider a session layer.

OSI's session management in connection with the typical transport protocols ( TCP, SCTP ), is contained in the transport-layer protocols, or otherwise considered the realm of the application layer protocols.

TCP / IP's layers are descriptions of operating scopes ( application, host-to-host, network, link ) and not detailed prescriptions of operating procedures or data semantics.