Functions of OSI Layers Seven Layers in OSI: Introduction to OSI, Layers in OSI and Importance of 7 Layers in OSI

Doorsteptutor material for competitive exams is prepared by world's top subject experts: get questions, notes, tests, video lectures and more- for all subjects of your exam.

Functions of OSI Layers: Seven Layers in OSI (Computer Science)


  1. Introduction on OSI
  2. Seven layers of OSI
  3. Functions of OSI layers
  4. Name of unit exchanged in different layers

Introduction on OSI

  • OSI stands for ‘Open System Interconnection’
  • It was established in 1970 by ISO i.e.. International Standards Organisation .
  • It is an ‘open source’ structure which means that it can be openly used for any environment and network easily for communication purpose.
  • It is a seven layered structured architecture.
Introduction on OSI

Functions of Seven Layers of OSI

1) Physical Layer:

  • Physical layer is responsible for movement of bits from one node to another.
  • Hardware cabling, wireless or wireline, everything is defined here.
Physical Layer
  • Synchronization of bits is also concerned here.

2) Data Link Layer:

  • It divides stream of bits received from network layer into units called frames.
  • It is also responsible for:
  • Flow control
  • Error control
  • Access control
  • Data Link Layer
    It is also responsible for physical addressing of frames.

3) Network Layer:

  • It is responsible for source to destination delivery of a packets across various networks.
  • It is also responsible for:
  • Logical addressing
  • Routing
  • Switching
Network Layer

4) Transport Layer:

  • It is responsible for:
  • Segmentation with sequence numbers
  • Reassembly of segments
  • Connection control
  • Flow control
  • Error control
  • Delivery of Message from one process to another
Transport Layer

5) Session Layer:

  • It is responsible for:
  • Dialog Control
  • Synchronization
Session Layer

6) Presentation Layer:

  • It is responsible for:
  • Translation (for encoding scheme)
  • Encryption
  • Compression
Presentation Layer

7) Application Layer:

  • It is responsible for:
  • File transfer
  • Management
  • Directory services
Application Layer

#OSI Layers

#Function of Physical Layer

#Function of Data Link Layer

#Function of Network Layer

#Function of Transport Layer

#Function of Session Layer

#Function of Presentation Layer

#Function of Application Layer