OSI AND TCP/IP MODELS : Today, a wide variety of computers and communication technologies are being used by organizations for performing their day-to-day tasks. These include mainframe computers, local area networks, workstations, personal computers, and proprietary and standards-based networking platforms. Not all of these products are inter-operable (at least, not easily), and it is not easy to exchange data across different systems and through different applications.
Open and inter-operable systems aim at resolving the difficulty in enabling any two computers of any size, regardless of the operating system and hardware platforms, to communicate. Therefore, standards were developed to ensure the interrelationship of the different standards adopted by vendors. To develop standards to suit different vendors there are some communication protocols that will be explained in the succeeding sections.

OSI AND TCP/IP MODELS – After going through this unit. you will be able to:
- Understand the concepts of protocol and transmission control procedure and understanding their significance and necessity
- Have an view of network architectures leading to the understanding of layering the communication process and the need for layered solutions
- Understand the Open Systems Interconnection (OSI) model of seven layers and their functions
- Develop a comprehensive understanding of the TCP IP protocol and data transmission by TCP and Ethernet. data encapsulation and data routing
- Establish correspondence between IP datagram and User Datagram Protocol (UDP)
- Explore the usage of upper-layer protocols such as FTP, TELENT