OSI Layers

Open System Interconnection (OSI) Reference Model

The Open Systems Interconnection (OSI) model (ISO/IEC 7498-1) describes how data from one application in one system moves through a network medium to an application in another system. It was developed in 1984. There are seven layers in OSI model. We will discuss functionality of each layer in following sessions.

The seven layers of OSI are,

1.      Physical layer

2.      Data link layer

3.      Network layer

4.      Transport layer

5.      Session layer

6.      Presentation layer

7.      Application layer

Seven layers of OSI

At each layer, some headers are added at the sender side and intended layers at the receiver remove the corresponding headers. It  means that, at each layer in the source system adds some control information to data, and each layer in the receiver system analyze and removes the control information from data.

Data representation at each layer of OSI

  A layer in OSI model generally communicate with other three layers: the layer just below it, the layer just above it, and the peer layer in other node.