Session Layer (Layer 5) tutorials

  • It Establishes connections, keeps different applications data separate, then terminates them after all the data has been sent.

  • It send syn (Synchronization) packets to establish connection, while receiver send back ack (acknowledgement).

  • Layer 5 is primarily concerned with dialog control among devices.

  • The Session layer is also provides dialog control between devices, or nodes.

  • This layer determines the beginning, middle, and end of a session or conversation that occurs between applications. In this way, the Session layer acts as an intermediary for those applications.

  • Following are Session layer protocol and its functionality.


Session Layer Protocol

Description / Functions

NFS (Network File System)

Accesses remote resources transparently and represents files and

directories as if local to the user system. Developed by SUN and

used on Unix workstations.

SQL (Structured Query Language)

SQL query language that requests, updates, and manages

databases. Developed by IBM and compatible with XML and HTML.

RPC (Remote Procedure Call)

Basis for client/server communications. Calls are created on the

client and then carried out on the server.

ASP (AppleTalk Session Protocol )

Also client/server–based communications, but specific to AppleTalk

client and server devices.

X Window

Communicates with remote Unix machines and enables the user to

operate the device as if attached locally.