Session Layer

Session Layer

The session layer allows users on different machines to establish sessions between them. Sessions offer various services, including dialog control (keeping track of whose turn it is to transmit), token management (preventing two parties from attempting the same critical. operation at the same time), and synchronization (check pointing long transmissions to allow them to continue from where they were after a crash).
» Session and sub sub-sessions : The layer divides a session into sub sessions for avoiding retransmission of entire messages by adding check pointing feature.

» Synchronization : The session layer decides the order in which data need to be passed to the transport layer.
» Dialog control : The session layer also decides which user/ application send data, and at what point of time, and whether the communication is simplex, half duplex or full duplex.
» Session closure : The session layer ensure that the session between the hosts is closed grace fully.