Modern networks are built in layers to simplify design, ensure compatibility, and make troubleshooting easier. Each layer has a specific role and communicates only with the layers directly above and below it. In this lesson, you will explore the purpose and function of these layers, focusing on the TCP/IP model.
Learning Objectives:
Define what a network layer is and why layering is used.
Identify and describe the four layers of the TCP/IP model.
Understand the role of each layer in sending and receiving data.
Explain how data moves through the layers.
Terminology:
Layer: A level of abstraction in network communication.
Application Layer: Interfaces directly with software applications (e.g. browsers).
Transport Layer: Ensures correct and reliable delivery of data.
Internet Layer: Responsible for addressing and routing data.
Link Layer: Manages the physical transmission of data across a network.
TCP/IP Model: A set of communication protocols structured into four layers.
The TCP/IP model consists of four layers:
Application Layer – Where communication begins, such as web browsing or email.
Transport Layer – Breaks data into packets and ensures it’s delivered correctly (e.g., using TCP).
Internet Layer – Assigns addresses and routes packets across networks using IP.
Link Layer – Handles the physical connection and transmission of raw data (e.g., Ethernet or Wi-Fi).
These layers work together to manage every aspect of data exchange, from what a user sees to how it’s transmitted and received.
Imagine sending a message in a bottle across the ocean. The application layer writes your message, the transport layer seals it into a waterproof container, the internet layer decides which ocean current to follow, and the link layer tosses it into the water. Each layer has its job, and together they get your message delivered safely.
Common Mistakes:
Mixing up the layers or their order.
Thinking data skips layers—it must pass through all.
Assuming only one layer is important; each plays a role.
Revision Summary:
The TCP/IP model simplifies networking by splitting tasks into layers.
Each layer only communicates with adjacent layers.
Layers ensure compatibility and ease of troubleshooting.
Comprehension Questions:
What is the main purpose of using network layers?
List the four layers of the TCP/IP model in order.
What does the Application Layer do?
Which layer ensures data is delivered correctly?
What role does the Internet Layer play?
What is handled by the Link Layer?
How do layers help with troubleshooting?
Can one layer function without the others?
Give a real-world example that illustrates all four layers.
What would happen if the Transport Layer failed?
Individual Activity:
Draw a labelled diagram of the TCP/IP model. For each layer, add one sentence explaining its function and one example.
Pair Activity:
With a partner, act out the TCP/IP model. One student is the sender, the other the receiver. Each person walks through each layer's function as if sending a message.
Small Group Activity:
Split the group into four. Each group researches one layer of the TCP/IP model and presents how that layer works using a classroom analogy.