OSI Model Layer 5- Session

The Session Layer establishes manages, synchronizes, and terminates connections between the computers. Since this layer defines the start and atop point for any conversion between two hosts, it is termed as a Session.

  • The Session layer allows uses on different machines to establish a ‘session’ between them before communication.
  • It controls the communication process.
  • It provides a dialog management facility.
  • It also helps the application for bi-directional communication and provides a messaging service during the communication process between the applications.


The characteristics of Layer 5 are:

  • The session layer sets up, coordinates and terminates interactions and dialog control between communication devices.
  • It provides either half-duplex service.
  • In the establishment phase, rules and services for a session between the two devices are negotiated. The participating devices must agree on the rules.
  • Once rules are accepted, the data transfer begins.
  • Connection is terminated once the ‘session’ is complete, and communication ends.

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