Open System Interconnection (OSI)

Open System Interconnection (OSI) reference model

• The ISO has created the OSI model, a seven-layer reference model for data networks.
• The model is named OSI because it focuses on connecting open systems that can communicate with other systems.
• It is an open system that is not tied to a specific system architecture, providing a standard framework for communication in telecommunication networks.
• The OSI model explains how data is transmitted between software applications on different computers through a network medium.
• It consists of seven layers, with each layer responsible for specific network functions.
• The OSI model breaks down the process of transmitting information between networked computers into seven manageable task groups.

Protocols of Computer Communications and Networks:

• Protocols are utilized for facilitating communication between computers in different computer networks. They address various aspects of communication, including what information is exchanged, how it is transmitted, when it is transmitted, and the expected conformance or structure of the exchanged data.
• The key elements of a protocol encompass:
• SYNTAX: This involves defining the data format and signal levels used for transmitting information.
• SEMANTICS: Control information is incorporated to handle coordination and manage errors during communication.
• TIMING: Synchronization, speed matching, and sequencing mechanisms are employed to ensure efficient data transmission.
• Examples of protocols include:
• WAN Protocol: TCP/IP, which is widely used for communication across wide area networks.
• LAN Protocol: Media Access Control (MAC) protocols such as Contention and Token Passing, which govern access to the shared communication medium in local area networks.

Protocol Architecture:

• The ISO/OSI Reference Model, also known as Open Systems Interconnection (OSI), is a conceptual framework for understanding and developing interfaces in computer networks.
• While the OSI model is not commonly used in practical network implementations, it serves as a valuable reference model for designing and understanding network protocols.
• The primary value of the OSI model lies in its division of communication functions into seven distinct layers, with each layer contributing its specific set of functions related to the communication process.

ISO/OSI Reference Model (2):