Q. Show the Responsibilities of session layer?

Session layer: Main functions of this layer are to establish, synchronize and maintain the interaction between two communication hosts. It ensures that once a session is established it should be closed gracefully. It also checks and establishes connections between hosts of two different users. Session layer also decides whether both users can send and receive data at the same time or whether only one host can send and the other can receive. Responsibilities of session layer are:

• Sessions and sub sessions: This layer divides a session into sub session for avoiding retransmission of whole message by adding checkpoint feature.

• Synchronization: This layer decides the order in which data needs to be passed to transport layer.

• Dialog control: this layer also decides which user application transmits data and at what point of time and whether communication is simplex, full duplex or half duplex.

• Session closure: this layer makes sure that session between hosts is closed gracefully.