The document discusses the Open Systems Interconnection (OSI) model, which is a 7-layer architectural framework for implementing network communication. The OSI model allows different types of systems to communicate by standardizing network components. Each layer has a specific role, with the physical layer coordinating signal transmission and the upper layers focusing on software interoperability and end-to-end reliability.

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

2. 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 To allow different types of network hardware and software to communicate with each other Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

3. ISO International Standard Organization Established in 1947 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 Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

4. Designed for communication across all types of computer system Layered framework 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 Related networking functions and its functionality are collected and discrete group ; became layer Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

5. Message from Device A to Device B Travels several intermediate Nodes These intermediate nodes involve only the first 3 layer P lease D o N ot T ouch S teve’s P et A lligator Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

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

7. 1 Peer to Peer Process 1. Sending bit stream form Machine A to Machine B 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) 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) Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

8. 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. Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

9. 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. Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

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

15. 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. Krishna Kumar Bohra (KKB), MCA LMCST www.selectall.wordpress.com

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