How a Network works

Table of Contents

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1 Learning Objectives

  • In this lesson you will develop an understanding of the learning strand Network and Communications on your progress ladder, working towards blue/indigo level.

Understanding and being able to explain:

  • What a Computer Network is
  • Different types of Computer Networks
  • What a router is and how it connects to devices
  • What packets are and how we use them to transfer data

2 What is a Computer Network?

A Computer Network is when we connect two or more computers together so they can communicate with eachother.

Learn It

  • There are many different types of network, with names like mesh, bus and ring.


  • Most networks you will have used will have been star networks.
  • Star networks are named because of the shape they have in diagrams.


  • Even though in reality they look more like this:


  • With the cables tucked away out of sight and leading back to the central hub.


Research It

  • The video below will give you an overview of how a Network works.

Document It

  • Having watched the video, try and produce a summary of it for your notes.

3 Packets and Routers

Learn It

  • The image below shows the devices that might make up a home network
  • Download the image (right click on it), and then open it up in a graphics package such as Paint or Photoshop.


Try It

  • Now label the devices using the list below.
    • Desktop Computer
    • Smartphone
    • Router
    • Media Player
    • Games Console.
    • Notebook

Learn It

  • We can connect up devices on a network using cable called Patch cables. You've probably got one coming out of the back of the computer you are using right now.
  • Patch cables are plugged into Ethernet Ports on devices.

Try It

  • On your diagram, draw on wires that link the the Ethernet ports on the Desktop Computer, Media Player and Games Console to the Router


Learn It

  • Some devices connect wirelessly.
  • WiFi stands for Wireless Fidelity.
  • WiFi uses radio waves to allow devices to communicate with each other.

Try It

  • On your diagram, add in something to indicate that the Router is able to connect to the Smartphone and Notebook using WiFi.

Research It

  • Devices can connect with each other using a few other methods. Use the Web to try and answer the following questions:
    • What is Bluetooth?
    • What is the range of Bluetooth communications
    • What are Fibre Optic cables?
    • What does 4G mean?

Learn It

  • Your diagram should probably look something like this now.


  • Let's imagine that the Desktop Computer is going to send an image file to the Media Player.
  • The image is called tree.jpg and has a size of 1.5MB (That's 1.5 Million bytes)


  • 1.5 Million bytes is too large to send in one go, so the Desktop Computer needs to break up the file into small chunks called packets
  • Each packet has an average size of about 1.5KB (That's 1500 bytes)
  • The Desktop Computer breaks up the image into packets, and adds some extra data onto the packet as well


  • Each packet is then sent to the Router.
  • When the Router receives a packet, it looks at the receiver's IP Address, and then sends the packet onto the correct device on the network.
  • The receiving device (in this case the Media Player) receives all these packets, and uses the packet number to assemble them all in the correct order.
  • Sometimes a packet get's lost or destroyed on the way. The receiving device will know that a packet is missing, and can use the sender's IP address to ask for the packet to be sent again.

4 A Presentation on Networks

Badge It

  • Imagine you had to try and explain how an image is sent over a network, from one device to another.
  • Create a presentation (using any software you like), and the image you drew earlier of a network, to explain how a file is sent over a network.
  • Your teacher will award you a silver, gold or platinum badge, depending on the clarity of your presentation.