The ISO - OSI Model document discusses the OSI model, which was created by the International Organization for Standardization to establish a standard for how systems use protocols to communicate over a network. The OSI model defines seven layers of network functionality, each building on the layers below. It allows different hardware and software components from different vendors to communicate by standardizing network communication. The model breaks network communication into smaller, simpler parts that are easy to develop and facilitates interoperability between devices.

1. The ISO - OSI Model a.k.a. OSI Model a.k.a. ISO OSI Reference Model 1 Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

2. Why ? To allow different types of network hardware and software to communicate with each other Avoidable duplication of equipment resources Inability to communicate efficiently To breaks network communication into smaller, simpler parts that are easy to develop To facilitates standardization of network components to allow multiple – vendor development and support 2 Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

3. Introduction Established in 1947 ISO International Standard Organization Multinational body dedicated to worldwide agreement Standard of international level Covers all aspects of network communications It is Open System Interconnection MODEL Allow two different Machines to connect without change in hardware and software It is model for understanding and designing a network architecture 3 Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

4. The Model Layered framework Designed for communication across all types of computer system 7 separate but related layer Each defines segment of process of moving information across network Developers / Designers distilled the process of transmitting data to its most fundamental element Creation of Layers Related networking functions and its functionality are collected and discrete group ; became layer 4 Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

5. Layered Architecture Message from Device A to Device B Travels several intermediate Nodes These intermediate nodes involve only the first 3 layer Please Do Not Touch Steve’s Pet Alligator 5 Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

6. Related required concepts Data of L7 layer passed to layer 6 Data of L6 layer passed to layer 6 Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

7. Related required concepts … 1 Peer to Peer Process Layer 2 provides services to Layer 3 (talking about Single Machine) Layer x provides services to Layer x (talking about In Between Machine) Communication between them governed by agreed upon series of rules - “Protocol” The process on each machine that communicates at given layer – “Peer to Peer Process” Only Physical layer (direct communication) 1. Sending bit stream form Machine A to Machine B 2. Data from Higher to move down 3. Sending machine adds its own info part to message 4. Added info are called ‘Header’(beginning of message) (Layers added Header 6,5,4,3,2) 7 Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

8. Related required concepts … 5. Added info are called ‘Trailer’(end of message) (Layers added Trailer 2) Every layer transform message for next layer At receiving end the message is unwrapped (It is for every layer) Interfaces between layers All receiving and sending of information and network information (between layers) only possible by interface ; between pairs of Layers. It defines what information, services a layer must provide to layer above it; process modulation. 8 Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

9. Related required concepts … Organization of layers Three subgroups 1 Layer (1,2,3) [Network Support Layer] Deals with physical aspect of data from 1 device to other device a. Electric Specification b. Physical Connection c. Physical Address d. Transport timing 2 Layer (5,6,7) [User Support Layer] Interoperability among unread software system 3 Layer (4) End to End reliability of data transmission (Layer4) Reliable transmission of link (Layer 3) The process of putting Header and Trailer goes on Layer by Layer (except Layer 7 and Layer 1), Layer 2 both have Header and Trailer. 9 Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

10. Related required concepts … User support layer Software Link between Software + Hardware N/W support layer Hardware Physical Layer > Changed info Electromagnetic signal > Physical Link > L1 > (transformed info into bits > than Layer by Layer Corresponding Header and Trailer removed. 10 Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

12. Representation of bits.

13. Physical topology.

14. Line configuration.

15. Data rate.

16. Synchronization of bits.

18. Physical addressing.

19. Flow control.

20. Error control.

21. Access control. 1 Raw transmission from physical layer to reliably link(node to node delivery). 2. Make physical layer error free. Data Link Layer 11 Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

24. Segmentation and reassembly.

25. Connection control.

26. Flow control.

27. Error control. Source to destination delivery of entire message across multiple network. 2. Connection establish, Data transfer and Connection release. Transport Layer 12 Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

30. Encryption.

31. Compression. 1. Concerned with syntax and semantics of the information exchanged between two system. Presentation Layer 13 Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

33. File transfer, access, and management.

34. Mail services.

35. Directory services. Application Layer and Summary Enable user, (human or software) to access the network. 2. Provides user interface and support for services (email, Remote file access, shared database management system). Application Layer 14 Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

36. Conclusion 1. The International Standards Organization created a model called the Open Systems Interconnection, which allows diverse systems to communicate. 2. The seven-layer OSI model provides guidelines for the development of universally compatible networking protocols. 3. The physical layer coordinates the functions required to transmit a bit stream over a physical medium. 4. The data link layer is responsible for delivering data units from one station to the next without errors. 5. The network layer is responsible for the source-to-destination delivery of a packet across multiple network links. 6. The transport layer is responsible for the process-to-process delivery of the entire message. 7. The session layer establishes, maintains, and synchronizes the interactions between communicating devices. 8. The presentation layer ensures interoperability between communicating devices through transformation of data into a mutually agreed upon format. 15 Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

37. Reference 1. Data Communications and Networking - Behrouz A. Forouzan 2. OSI model - Wikipedia, the free encyclopedia 16 Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com