Discuss in details the open system interconnection (OSI) model. In your discussion highlight on the layers and it's functionality including the references?

The Open Systems Interconnection (OSI) model is a conceptual framework that standardizes the functions of a telecommunication or computing system into seven distinct layers. Each layer in the OSI model performs a specific set of functions that enable communication between different devices on a network. The OSI model was developed by the International Organization for Standardization (ISO) in the late 1970s and early 1980s.

The seven layers of the OSI model are as follows:

1. Physical Layer: The physical layer is responsible for transmitting raw data bits over a physical medium, such as cables or wireless signals. It defines the electrical, mechanical, and procedural aspects of communication.

2. Data Link Layer: The data link layer is responsible for establishing, maintaining, and terminating connections between devices on a network. It also handles error detection and correction, as well as flow control.

3. Network Layer: The network layer is responsible for routing data packets between different networks. It determines the best path for data to travel from the source to the destination, based on factors such as network congestion and traffic.

4. Transport Layer: The transport layer is responsible for ensuring that data is delivered reliably and in the correct order. It also handles error detection and recovery, as well as flow control.

5. Session Layer: The session layer is responsible for establishing, maintaining, and terminating sessions between applications on different devices. It also handles synchronization and checkpointing of data.

6. Presentation Layer: The presentation layer is responsible for translating data into a format that can be understood by the application layer. It also handles data compression and encryption.

7. Application Layer: The application layer is the topmost layer of the OSI model and is responsible for providing network services to applications. It includes protocols such as HTTP, FTP, and SMTP.

Each layer in the OSI model communicates with the layers above and below it through defined protocols and interfaces. This modular approach to networking allows for easier troubleshooting, scalability, and interoperability between different devices and systems.

References:
1. Stallings, William. "Data and Computer Communications." Pearson, 2013.
2. Tanenbaum, Andrew S. "Computer Networks." Pearson, 2011.
3. ISO/IEC 7498-1:1994, "Information technology - Open Systems Interconnection - Basic Reference Model: The Basic Model."

Open System Interconnection (OSI) Model

The OSI model is a conceptual framework for understanding how computer systems communicate. It was developed by the International Organization for Standardization (ISO) in the 1980s and is widely used as a reference model for network design and implementation.

The OSI model consists of seven layers, each of which performs a specific function in the communication process:

1. Physical Layer
- Responsible for the physical transmission of data over a network medium (e.g., cables, fiber optics, wireless).
- Functions include: bit transmission, encoding/decoding, signal modulation/demodulation, and error detection.

2. Data Link Layer
- Establishes and maintains reliable point-to-point connections over the physical layer.
- Functions include: error checking, flow control, media access control (e.g., Ethernet, Wi-Fi), and frame addressing.

3. Network Layer
- Provides routing and network addressing services for data transmission across multiple networks.
- Functions include: IP addressing, routing protocols (e.g., TCP/IP, IPv6), network layer error detection, and traffic routing.

4. Transport Layer
- Provides reliable and sequenced transport of data between end-point applications.
- Functions include: error recovery, flow control, data segmentation/reassembly, and port addressing (e.g., TCP, UDP).

5. Session Layer
- Manages and synchronizes communication sessions between applications.
- Functions include: session establishment/termination, session negotiation (e.g., encryption, compression), and token management.

6. Presentation Layer
- Translates and formats data between different application protocols and the network.
- Functions include: data encryption/decryption, data compression/decompression, and data conversion (e.g., ASCII, Unicode).

7. Application Layer
- Provides user-specific services and applications through the network.
- Functions include: file transfer (e.g., FTP), email (e.g., SMTP), web browsing (e.g., HTTP), and multimedia applications.

Interlayer Communication

Each layer of the OSI model communicates with the adjacent layers using specific protocols. For example:

- Physical layer: Transmission Control Protocol (TCP)
- Data link layer: Ethernet frame
- Network layer: Internet Protocol (IP)

References

- [OSI Model](https://en.wikipedia.org/wiki/OSI_model)
- [ISO/IEC 7498-1:1994](https://www.iso.org/standard/14988.html)
- [Computer Networks: A Top-Down Approach, 8th Edition](https://books.google.com/books?id=z7euBwAAQBAJ&pg=PA27)
- [OSI Model in Detail: 7 Layers Explained](https://www.geeksforgeeks.org/osi-model-in-detail-7-layers-explained/)