3_5_4 Understand TCP/IP

You should be able to:

Describe the 4 layer TCP/IP model:

•• application layer

•• transport layer

•• internet layer

•• link layer.

Understand that the HTTP, HTTPS, SMTP, IMAP and FTP protocols operate at the application layer.
Understand that the TCP and UDP protocols operate at the transport layer.
Understand that the IP protocol operates at the internet layer.

REVISE:

Make sure that you have read and understood 3_5_2 before you revise this section.

The Four Layer TCP / IP Model

The Application Layer

PROTOCOLS: HTTP, HTTPS, SMTP, IMAP and FTP

Web browsers and email application would work in this layer of the TCP/IP model.

The Transport Layer

PROTOCOLS: TCP (checks for errors) and UDP (just sends the data)

This is where communication is agreed and set-up.

The Internet Layer

PROTOCOLS: IP

The routes and addresses are created and used with this layer.

The Link Layer

PROTOCOLS: Ethernet / Wi-Fi

The physical hardware required to make the connection.

A summary:

In order to communicate over a network you need physical hardware (wires / network interface cards / Wi-Fi cards etc). This is known as the link layer. Once you have the gear, you need a way to be recognised so that communication can happen. This is your IP address or the Internet Layer. Before you can send and receive data you need to know what you are sending / receiving and how large it is. The receiver needs to agree that this is OK as well. This is the Transport Layer. The final layer is the Application Layer. You need to be able to access the data that you have received so an application will help you to do that.

The diagram is read from BOTTOM to TOP so the order is LINK, INTERNET, TRANSPORT, APPLICATION.

How could you remember this???

TCP / IP >> DON'T DROP LITA

Link, Internet, Transport, Application

TEST:

Download and print the test paper here: https://drive.google.com/open?id=0B5fLtQ0Xgr2PNDAwTnlBaHhVR2s
Try the mock test yourself.
Use the 3.5.4 Walking Talking Mock below to guide you through answering the questions.

SOURCE RECOGNITION - PLEASE NOTE: The examination examples used in these walking talking mocks are samples from AQA from their non-confidential section of the public site. They also contain questions designed by TeachIT for AQA as part of the publicly available lesson materials.

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