4 – Packets and Routers

📖 Learning Objectives

Develop the Network and Communications learning strand:

  • Understand what the what a computer network is
  • Explore different types of computer networks
  • Discover what a router is and how it connect devices together
  • Understand what packets are and how we use them to transfer data
💬 Key Vocabulary

  • network
  • communication
  • router
  • packets
  • header
  • topology

📝 Starter Activity – What is a Computer Network?

  • Open a new Word file and write down a definition of what you think a computer network is at the moment.

🌐 What is a Computer Network?

  • A Computer Network is when we connect two or more computers together so they can communicate with each other.
  • There are many different types of network, with names like mesh, bus and ring.
  • The star network topology is the type you will have used the most, it is also the type used here at school.
  • Your computer is connected by copper ethernet cables to a central server elsewhere in the school.
Network topology types
Even though in reality they look more like this
With the cables tucked away out of sight and leading back to the central hub
  • The video below will give you an overview of how a network works:
  • Having watched the video, try and produce a summary of it for your notes.

🖧 Routers

  • The image here shows the devices that might make up a home network.
  • Save the image by right clicking on it, and then open it up in PowerPoint.
  • Then label the devices using the list below.
    • Desktop Computer
    • Smartphone
    • Router
    • Smart TV
    • Games Console
    • Laptop

Ethernet Cables

  • We can connect up devices on a network using cables called ethernet cables. You’ve probably got one coming out of the back of the computer you are using right now.
  • Ethernet cables are plugged into ethernet ports on devices.
Ethernet_ports.jpg
Ethernet ports, check the back of your computer to find them
  • On your diagram, draw on lines that link the the ethernet ports on the Desktop Computer, Smart TV and Games Console to the Router.
  • Think about why these devices should be connected by cables and not wirelessly.

Wi-Fi

  • Some devices connect wirelessly. Wi-Fi stands for Wireless Fidelity.
  • Wi-Fi uses radio waves to allow devices to communicate with each other.
  • On your diagram, add in a Wi-Fi icon to indicate that the Router is able to connect to the Smartphone and Laptop using WiFi.

Other Connection Technologies

  • 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 5G mean?

Your diagram should probably look something like this now:

🖧 Packets

  • Let’s imagine that the desktop computer is going to send an image file to the laptop.
  • The image is called tree.jpg and has a size of 1.5MB (That’s 1.5 Million bytes).
A high quality tree image
  • 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 laptop) 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.

🖧 A Presentation on Networks

  • Imagine you had to try and explain how an image is sent over a network, from one device to another.
  • Create a presentation using PowerPoint, 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.

In this lesson, you…

  • Explored how a network works including different types of network.
  • Looked at routers and packets and how they are used to transport data on a network.

Next lesson, you will…

  • Use Scratch to model a network including how packets move around a network.
  • Use our DNS model from last lesson to include it in our network.

🏅 Badge it

🥈 Silver Badge

  • Presentation shows some information on how a file is sent over a network.
🥇 Gold Badge

  • Presentation shows clearly how a file is sent over a network.
🥉 Platinum Badge

  • Presentation shows clearly how a file is sent over a network with extra detail and information.