what is osi model | what are seven layer of OSI model | function of OSI model.

what is OSI model | what are seven layer of OSI model | function of OSI model.

OSI Reference Model

INTRODUCTION

• Stands for open system interconnection.
• It has 7 layers.
• Each layer having specific functionality to perform.
• All layers work collaboratively to transmit the data from one person to another across the globe.

 

         

              

All 7 layers of OSI model explain briefly:

Physical layer

• To move data in the form of electromagnetic signals across a transmission medium.
• Responsible for movements of individual bits from one hop (Node) to next hop.
• Both data can be either analog or digital.
• Transmission media of data which can be wired or wireless.
  

 

Data link layer

• It is responsible for moving frames from one hop to the next.
• Responsible for error free transfer of data frames.
• Controls the flow of data.

Network layer

• The network layer works for the transmission of data from one host to the other located in different networks.
• It also takes care of packet routing i.e. selection of the shortest path to transmit the packet, from the number of routes available.
• The sender & receiver’s IP addresses are placed in the header by the network layer.

Transport layer

• The Transport layer is a Layer 4 ensures that messages are transmitted in the order in which they are sent and there is no duplication of data.
• The main responsibility of the transport layer is to transfer the data completely.
• It receives the data from the upper layer and converts them into smaller units known as segments.
• This layer can be termed as an end-to-end layer as it provides a point-to-point connection.

Session Layer

• This layer is responsible for the establishment of connection, maintenance of sessions, authentication, and also ensures security.
• Allows the communication between processes which can be either half or full duplex.
  

Presentation Layer

• Presentation layer is responsible for converting data into standard format.
• Examples : jpeg, mpeg, mp3, etc.
• Following tasks are perform :

• Encoding – Decoding
• Encryption – Decryption
• Compression – Decompression

 

Application Layer

• Application layer is responsible for providing networking services to the user.
• Also known as desktop layer.
• Also makes a request to its bottom layer, which is presentation layer for receiving various types of information from it.
• Provides protocols that allow software to send and receiven information and present meaningful data to users.