OVERVIEW ON THE SEVEN LAYERs OF COMPUTER NETWORK

OVERVIEW ON THE SEVEN LAYERs OF COMPUTER NETWORK.

1. The Osi Model OVERVIEW ON THE SEVEN LAYERs OF COMPUTER NETWORK ( Sumit Kumar , Sumit Dalal , Vivek Dixit) Presented By: Waqas Ahmad BS Telecommunication Su-12-01-003-005 6 th semester Presented To: Mr. Adam Khan Dept. Computer Science And IT

2. Overview Abstract OSI HISTORY Open Systems Interconnection Model (OSI Model) Component of OSI Model Osi Model Arch Function of each layer Conclusion

3. Abstract The Open Systems Interconnection model (OSI model) is a product of the Open Systems Interconnection effort at the International Organization for Standardization. It is a way of sub-dividing a communications system into smaller parts called layers. A layer is a collection of conceptually similar functions that provide services to the layer above it and receives services from the layer below it. On each layer an instance provides services to the instances at the layer above and requests service from the layer below. For example, a layer that provides error-free communications across a network provides the path needed by applications above it, while it calls the next lower.

4. OSI HISTORY In the late 1970s, two projects began independently, with the same goal One was administered by the International Organization for Standardization (ISO ). other was undertaken by the International Telegraph and Telephone Consultative Committee. These two international standards bodies each developed a document that defined similar networking models. Goal of The project: define a unifying standard for the architecture of networking systems

5. OSI HISTORY In 1983, these two documents were merged to form a standard called The Basic Reference Model for Open Systems Interconnection. The standard is usually referred to as the Open Systems Interconnection Reference Model, the OSI Reference Model, or simply the OSI model . It was published in 1984 by both the ISO and the renamed CCITT (now called the Telecommunications Standardization Sector of the International Telecommunication Union or ITU-T )

6. Open Systems Interconnection Model (OSI Model) The Open Systems Interconnection (OSI) Model is a conceptual and logical layout that defines network communication used by systems open to interconnection and communication with other systems. The model is broken into seven layers Physical Layer Data link Network layer Transport layer Session layer Presentation Layer Application Layer

7. Component of OSI Model OSI had two major components abstract model of networking, called the Basic Reference Model or seven-layer model , set of specific protocols . The concept of a seven-layer model was provided by the work of Charles Bachman.

8. Osi Model Archi

9. Function of Each Layer(1) Application Layer: The Application layer is the first layer of the OSI Model. The physical layer deals with: Physical Medium This layer plays with most of the network’s physical connections: wireless transmission cabling, etc

10. Function of Each Layer(2) Date Link Layer: The data link layer is used for the encoding, decoding and logical organization of data bits. Data packets are framed and addressed by this layer, which has two sublayers . The data link layer's first sub layer is the media access control (MAC) layer. It is used for source and destination addresses. The MAC layer allows the data link layer to provide the best Data Transmission and manage data flow control. The data link layer's second sub layer is the logical link control. It manages error checking and Data flow over a network.

11. Function of Each Layer(3) Network Layer: The network layer is the third level of the Osi Model. Provides data routing paths for network communication Selects and manages the best logical path for data transfer between nodes This layer contains hardware devices such as, Routers switches, etc

12. Function of Each Layer(4) Transport Layer: Responsible for end-to-end communication over a network The transport layer is also responsible for the management of error correction To Transport the Data Addressing is not the responsibility of Transport layer Services provided by Transport layer Reliable Unreliable Issues control by Transport layer Segmentation Sequencing Flow control

13. Function of Each Layer(5) Session Layer: Session between Applications Establishing Managing Terminating To manage the session Dialog Control Two way Alternative Two way Simultaneous Dialog Separation Roll Back Check Point

14. Function of Each Layer(6) Presentation Layer: The presentation layer formats the data to be presented to the application layer. This layer may translate data from a format used by the application layer into a common format at the sending station, and then translate the common format to a format known to the application layer at the receiving station. The presentation layer provides: Data compression Data encryption Data conversion

15. Function of Each Layer(7) Application Layer : Provide an interference When user communicate wit ha computer hardware Applications may be: Stand alone Network application

16. CONCLUSION The authors tried to explain what exactly an OSI reference model is, OSI is basically an architecture which only gives us an idea how packets transfer over the network during any communication. OSI enhancements are done time to time for developing new technologies.