OBJECTIVES
This chapter covers the following CompTIA-specified objectives for the “Protocols and Standards” section of the Network+ exam:
Identify the seven layers of the OSI model and their functions.
The OSI reference model provides a theoretical framework that is used to describe the processes and technologies associated with networking.
Identify the OSI layers at which various network components operate including:
Hubs
Switches
Bridges
Routers
Network interface cards (NICs)
Understanding how devices' functions relate to the OSI model can provide a greater understanding of networking principles.
OUTLINE
Introduction
Why Do We Need a Network Model?
OSI Reference Model 101
Layer 1: The Physical Layer
Layer 2: The Data-Link Layer
Layer 3: The Network Layer
Switching Methods
Network-Layer Addressing
Layer 4: The Transport Layer
Connection-Oriented Protocols
Connectionless Protocols
Flow Control
Layer 5: The Session Layer
Layer 6: The Presentation Layer
Layer 7: The Application Layer
OSI Model Summary
The Layers at Which Devices Operate
Hubs
Switches
Bridges
Routers
NICs
Summary of the Layers at Which Devices Operate
Chapter Summary
Apply Your Knowledge
STUDY STATEGIES
Read the objectives at the beginning of the chapter.
Study the information in the chapter, paying special attention to the tables, which summarize key information.
Review the objectives again.
Answer the exam questions at the end of the chapter and check your results.
Use the ExamGear test on the CD-ROM that accompanies this book to answer additional exam questions concerning this material.
Review the notes and exam tips in this chapter. Make sure you understand the information in the exam tips. If you don't understand the topic referenced in an exam tip, refer to the information in the chapter text and then read the exam tip again.