Session Layer in OSI Model: Functions, Protocols, Examples, Devices

Session Layer in OSI Model: Functions, Protocols, Examples, Devices

What is Session Layer

Definition: The session layer occupies the 5th position of OSI model. This layer depends on the transport layer, and it grabs all services which are offered by the transport layer.

session layer

Session layer has responsible for managing, establishing, synchronizing and terminating all sessions in between local and remote application.

Functions of Session Layer

  1. It allows dialoging control, and it helps to make communication in between in half-duplex or full-duplex.

Steps to build a session connection with two peer session services users, Follow these steps –

  • Getting to map session address with shipping address
  • Choose needed transport quality of service parameters.
  • Session parameters are getting negotiation.
  • Determine every session connections.
  • Transfer limited user data.
  • Data transmission cycle
  1. This layer enables with token management because it helps to protect two lines from getting similar most critical operation at once.
  1. Synchronization: Session layer enables with a process for attaching checkpoint which are worked as synchronization points into the data. Due to this synchronization, all errors can be identified, and all data is getting re-synchronized, and ends of the messages are not cut prematurely, as well as preventing loss of data.

Protocols of Session Layer

Session layer is used different types of protocols; below explain each one –

Examples of Session Layer

These protocols are also known as examples of session layer protocols; such as-

Remote procedure call protocol (RPC): RPC protocol is used for requesting a service one computer to another computer system over the network without knowing any information of network.

Point-to-Point Tunneling Protocol (PPTP): This protocol is used for establishing Virtual Private Network (VPN) tunnels in between other public network.

Session Control Protocol (SCP): SCP protocol is used to make light duty connections from single TCP connections, and those lightweight connections can be active at once..

Session Description Protocol (SDP): This protocol is used to define all parameters for transferring all multimedia in between two end systems.

AppleTalk Data Stream Protocol (ADSP): ADSP is a connection oriented protocol, and it helps to transfer full-duplex streams of data over the AppleTalk internet.

AppleTalk Session Protocol (ASP): This protocol allows multiple ASP workstation applications for building the session along with same server at once.

Internet Storage Name Service (iSNS): This protocol deals with automation of discovery and management of iSCSI devices over a TCP/IP storage network. It keeps all information like as their IP addresses, iSCSI node names, and portal groups.

Other Session Protocols are:-

  • Call Control Protocol for Multimedia Communication
  • OSI session-layer protocol (X.225, ISO 8327)
  • Layer 2 Forwarding Protocol
  • Layer 2 Tunneling Protocol
  • Network Basic Input Output System
  • Password Authentication Protocol

Design Issues with Session Layer

  • To enable all machines to build sessions in between them in seamless nature
  • To offer increased services to end user
  • To handle dialog control
  • To offer several services like as Token management and Synchronization.

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