OSI_Model_Presentationcyber security class

OSI_Model_Presentation cyber security class

1. Data Communication: OSI Model Unit II Lecture 03 Cyber Security

2. The OSI Model Introduced in 1983 The OSI model has seven layers The OSI model is not a network architecture — lt does not specify the exact services ant protocols It specifies what kind of functions each layer should perform ISO has produced standards for each layer as separate documents Good model to study networking concepts

3. Introduction to OSI Model The OSI (Open Systems Interconnection) model is a conceptual framework for designing network architecture. It consists of seven distinct layers that work together to facilitate communication between diverse systems. Each layer has unique responsibilities, ranging from application-level user interaction to physical signal transmission. Understanding the OSI model ensures data is properly formatted, transmitted, and received across different networks. Knowledge of this model is crucial for effective data communication and network management.

4. Origins and Purpose of OSI Model The OSI model was introduced by the International Standards Organization (ISO) in 1972 as a universal reference for communication systems. Its goal is to standardize network communication and ensure interoperability between devices, systems, and architectures. The model divides communication into seven functional layers, each performing specific tasks to enhance overall efficiency. This layered approach simplifies troubleshooting and development by isolating issues within specific layers. The OSI model is also essential for cybersecurity as it helps in identifying vulnerabilities within each communication layer.

5. Data Transmission in OSI model Sarding T‹ /t Treneport Dna Tink 5H OT Physical

6. Flow of Data Across Layers Data flows through various OSI layers, moving from higher to lower levels as it is transmitted across the network. The Application layer serves as the interface for users, enabling communication through applications such as browsers and messaging tools. Network protocols like FTP (File Transfer Protocol) facilitate reliable file transfer across different systems, ensuring data integrity. The Presentation layer translates data into a format suitable for transmission, including tasks like encryption and compression. This process ensures seamless interaction between applications and the underlying network infrastructure.

7. The Data Link Laye r Providing error-free transmission line for upper layers between two adjacent nodes Breaking information into frames and using services of physical layer Error- detecting codes Error-correcting codes Ensuring uniqueness and correctness of frames Flow control between sender and receiver Access to shared communication channel

8. Data Compression and Security Data compression reduces the size of information, making it easier to store and transmit efficiently across networks. The Presentation layer plays a central role in data management, handling compression, translation, and formatting of information. Efficient data handling is essential for maintaining both storage efficiency and security. Authorization mechanisms such as email and password validation ensure that only authenticated users gain access to sensitive resources. This layered security protects systems from unauthorized access and potential cyber threats.

9. Transport Layer Functions The Transport layer is responsible for reliable end-to-end delivery of data between systems across a network. It segments data into smaller units called segments, which are then reassembled at the destination. Flow control mechanisms manage the pace of data transfer, preventing congestion and data loss. Protocols like TCP (Transmission Control Protocol) operate at this layer to ensure reliability, sequencing, and error checking. This layer guarantees that data is delivered accurately and in the correct order.

10. The Physical Layer Transmission of raw bits over communication channel Transmission media, its physical properties Magnetic media Twisted pair Coaxial cable Fiber optics Wireless transmission Data rate of communication channel

11. Logical and Physical Addressing Logical addressing using IP addresses provides unique identities for devices, enabling smooth communication over the internet. The Data Link layer converts data packets into frames, preparing them for transmission over the physical medium. Each device has a unique MAC address, which identifies the source and destination during data transmission. This ensures precise routing of information within a network, minimizing misdelivery or errors. Different OSI layers collaborate to ensure accurate sending, routing, and receiving of data.

12. Physical and Data Link Layers The Physical layer is responsible for converting data into signals suitable for transmission, such as electrical pulses or radio waves. This conversion enables data to travel over different types of media including cables, fiber optics, and wireless channels. The Data Link layer validates destination MAC addresses, ensuring that information reaches the intended device without errors. The Transport layer adds encapsulation, ensuring reliable transmission of data packets across the network. Each OSI layer contributes specific functions to maintain accuracy and efficiency in communication.

13. The Netwo rk Laye r Routing of data packets from source host to destination host Controlling network congestion Accounting of network traffic Internetworking - interconnection of multiple heterogeneous networks — Addressing issues Packet sizes Protocol differences

14. The Transport Layer Transmission of data between software entities on end-point hosts Providing channel for each application, mapping channels to Network Layer connection Ensuring uniqueness and correctness transmitted of data units Quality of Service (QoS) management Connection management, naming Flow control and buffering

15. The Session Laye r Establishment of sessions between applications Enhancing Transport Layer services Dialogue control: directions, etc. Token management Synchronization: checkpoints

16. The Presentation Laye r Providing general solutions to syntax and semantics transmitted data Encoding of data “on the wire” into intemediate format Compression of data Encryption of data

17. The Application Layer All the network application software Network virtual terminals File transmission Electronic mail File servers Database servers Application servers Object servers Transaction servers