ITFT_Osi reference model


Published on

Basics of OSI reference Model

Published in: Education, Technology, Business
  • Be the first to comment

  • Be the first to like this

ITFT_Osi reference model

  1. 1. OSI Reference Model
  2. 2. Why to learn OSI reference Model? The answer is too simple that It tells us that how communication takes place between computers on internet but how??
  3. 3. Nowadays, When we talk about communication of computer we got to know a term communication protocols. What are they?? Set of rules which defines the rules followed by all involved in the process of communication but what are they actually??
  4. 4. What if someone is using some other rules/Protocols? If it is necessary to communicate with computers following totally different protocols then we have to connect a device called Gateway between such systems. Gateways are computers loaded with special software, which do the job of translation work from one protocol to other so that communication between heterogeneous systems may take place.
  5. 5. The Seven-layer Architecture of the OSI model
  6. 6. PHYSICAL LAYER TRANSMISSION MEDIUM From Data link Layer To Data link Layer
  7. 7. • Physical layer is the bottom layer of OSI model • It is responsible for the actual physical connection between the devices. Such physical connection may be made by using twisted pair cable, fiber-optic, coaxial cable or wireless communication. • Physical layer is concerned with transmitting raw bits over a communication channel.
  8. 8. Function of Physical layer • Transforming bits into signals • Bit Synchronization • Provides physical characteristics of interfaces and medium • Bit rate control • Line configuration • Transmission mode • Physical topologies • Multiplexing • Circuit switching
  10. 10. Functions of Data link layer • Framing • Physical Addressing • Flow control • Error control • Access Control • Feedback
  11. 11. Network Layer
  12. 12. Functions of Network layer • Logical Addressing • Routing
  13. 13. Transport Layer • Transport layer provides two types of services • Connection oriented • Connectionless
  14. 14. Session Layer
  15. 15. Function of Transport layer • Segmentation of message into packet and reassembly of packets into message • Connection management • Service point addressing • Flow control • Error control
  16. 16. Function of Session layer • Establishment, maintaining and ending a session • Dialog control • Dialog separation or Synchronization
  17. 17. Presentation Layer • Different computers may use different coding schemes for data transmission. For example some computers may send the most significant bit of a byte first and least significant bit last and in some other computers it may be other way round, the sequence may be different at byte level also. The job of the presentation layer is to do the job of code translation and present the data in the format used at the destination computer.
  18. 18. Functions of presentation layer • Data Presentation or Translation • Data Encryption • Data compression
  19. 19. Application Layer • This is the layer with which users have direct interface. At the transmitting computer the message originates at this layer and at the destination computer the message is finally received by this layer and presented to the user in desired format. The data packets at the application layer are known as messages
  20. 20. Functions of Application Layer • Network Virtual Terminal • File transfer, access and management (FTAM) • Mail services • Directory services