Chapter 12.1 - Introduction to the OSI Model
Chapter 12.2 - Physical Layer (Layer 1)
Chapter 12.3 - Data Link Layer (Layer 2)
Chapter 12.5 - Transport Layer Fundamentals (Layer 4)
Chapter 12.6 - Session Layer (Layer 5)
Chapter 12.6 - Presentation Layer (Layer 6)
Chapter 12.7 - Application Layer (Layer 7)