How OSI model came into the picture? What is a network model? OSI Reference Model in Networking? What are the 7 layers of the OSI Model? OSI layer protocols and functions- 1. Application Layer Function and protocols 2. Presentation Layer Function and Protocols 3. Session Layer Functions and Protocols 4. Transport layer Functions and Protocols 5. Network Layer Functions and Protocols 6. Data Link Layer Functions and Protocols 7. Physical Layer Functions and Protocols