Introduction
This blog will mainly discuss the session layer of the OSI model. Before jumping on the session layer, let us first understand an OSI model. The Open Systems Interconnection model is commonly referred to as the OSI model. It is the framework used to describe all the functions of the networking system.
Now, talking about the session layer, it is the 5th level of the OSI model. There are seven layers in the OSI model (Physical, Data Link, Network, Transport, Session, Presentation, and Application). The session layer is responsible for maintaining the connections and controlling ports and sessions.
Now, let's discuss the session layer in detail.
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Session layer
As discussed above, the session layer is the 5th layer of the seven layers OSI Model. Session Layer helps establish an active communication session between the users on different machines. Its main goal is to establish, maintain, and synchronize the interaction between both systems. The session layer is responsible for explaining the process of starting, controlling, and ending the conversations between the devices. It finds the proper connection and then sends the data across it. This layer also supports Full-Duplex or Half-Duplex Operations. The session layer communicates with the transport layer and sets up and tears down the connection. It replies to the tickets requested from the presentation layer and issues service requests to the transport layer.
Protocols of Session Layer
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Session Control Protocol (SCP)
The protocol allows a server and the client to have multiple transmissions over a single TCP connection. The primary service of the SCP is dialogue control.
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AppleTalk Session Protocol (ASP)
This protocol establishes a session between an ASP workstation device and an ASP server. AppleTalk Session Protocol provides an application programming interface for the workstation side.
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Appletalk Data Stream Protocol (ADSP)
It is the protocol that Apple Inc developed. It allows local area networks to be connected with no setup, which must be done before the connection. It has two protocols: AARP and NBP.
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Point-to-Point Tunneling Protocol (PPTP)
PPTP or Point to Point Protocol is a protocol that provides a method for implementing virtual private networks. It uses a TCP control channel and a Generic Routing Encapsulation tunnel to encapsulate PPP packets. PPTP's security and remote access levels are compatible with typical VPN products.
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Remote Procedure Call Protocol (RPC)
RPCP or Remote Procedure Call Protocol is when a procedure is caused by a computer program and needs to execute in a different address space without explicitly coding the details for the remote interaction. It served as the form of client-server interaction and was implemented via a request-response message-passing system.
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Password Authentication Protocol (PAP)
PAP or Password Authentication Protocol is a password-based authentication protocol. PAP is used by PPP(Point to Point) to validate the users. Supported by almost all remote servers and network operating systems, PAP does the authentication while establishing the Initial link. It verifies the user using a two-way handshake between client and server.
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Real-time Transport Control Protocol (RTCP)
RTCP, or Real-time Transport Protocol, provides out-of-band statistics and controls Real-time information sessions. RTCPs majorly help us provide feedback on the quality of service (QoS) in media distribution. RTCP periodically sends the statistical information such as octet transmitted and counts of packets or loss of packets to the participants in the streaming multimedia session.
The Functions of the Session Layer
So till now, we have seen the session layer in detail. We have also discussed the different protocols of the session layer. Now, let's look into the functions of the Session Layer. Below are the functions performed by the session layer
- The session layer maps the session address to the shipping address.
- The connection is established between the session entities.
- A three-way handshake connection is established.
- The session layer negotiates the parameters of the sessions.
- It selects the required transport quality of services (QoS) parameters.
- It is responsible for identifying each session's connections.
- It is also responsible for synchronizing information from different sources.
Also read, Basic Networking Commands
Must Read Stop and Wait Protocol.