Open System Interconnection Model (ISO-OSI Model)

OSI model includes seven layers: 1. Physical Layer 2. Datalink Layer 3. Network Layer 4. Transport Layer 5. Session Layer 6. Presentation Layer 7. Application Layer

The OSI model is an Open System Interconnection Model, which is introduced by ISO (International Standard Organization). This model is used to control the networking and communication, also to protect the data from the intruder, etc.

This model is basically consists of seven layers, and all the protocols are designed on the basis of this OSI model. But now a days, many protocols are depends on TCP/IP model for the communication network.

This model is introduced to make the communication easy and effective, OSI is like a framework for all the communication network to access information and exchange information. The main idea behind this is to develop standard protocols, which are used to carry data and protect the data in every layer in a different format with different header.

The main function of OSI model is to define those types of layers and protocol service, which can perform operations in between the seven layers. There are some logical and physical functions of all the layers and protocols. But I will tell you about only the seven layers:

1. Physical Layer:
The function of this layer is to perform physical services in the OSI model,like
a. Representation of Bits
b. Topology
c. Line Configuration
d. Data Rate
e. Physical Characteristics of Cable
This layer is only responsible for the coordination of mechanical, electrical specification of the cable.

2. Datalink Layer:
The function of this layer is to perform the addressing and control the frame (data). It is also divided into two parts, Medium Access Layer (MAC), Logical Link Control (LLC).
a. Framing
b. Physical, Ethernet, MAC addressing
c. Flow, Error, Access Control

3. Network Layer:
The function of this layer is to select the suitable path for the packet (data).
a. Logical Addressing
b. Packetization
c. Routing of Packets
d. Controls and give address to the outgoing packets
e. Decode the address of incoming packets.

4. Transport Layer:
The function of this layer is to deliver the data end to end (point to point).
a. Port Addressing
b. Segmentation and reassembly
c. Connection, flow, error control
d. Maintain packet order

5. Session Layer:
The function of this layer is to create checkpoints to check the error in the data or packet.
a. Dialog Control
b. Synchronization
c. Session Maintenance
d. Perform Check-points

6. Presenstion Layer:
The function of this layer is to deal with the security of the data.
a. Translation of data
b. Encryption of data
c. Compression of data

7. Application Layer:
The function of this layer is to provide the interface to the user or the end machine.
a. Mailing Service
b. World Wide Web
c. Remote Login.


Every technology make the working of humans easy and time-saving, this OSI model has very much importance in our WWW and communication network. My idea is to encourage every people to use every technology up to some extent and enjoy the technology for the communication, networking, etc.


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