Y8 - Computer Networks Explained
This resource explains how computer networks work, starting with simple local networks and building up to how data travels across the internet.
1. Basic Network (No Switch – Mesh Topology)
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This is a very simple network where each computer is connected directly to the others. There is no central device such as a switch.
This type of network can be cheap to set up for a very small business, as no switch is required.
However:
- As more computers are added, the amount of cabling increases
- Maintenance becomes difficult
- If one cable fails, it can affect communication
Because of this, mesh-style local networks are rarely used in practice.
2. Star Network Using a Switch
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In a star network, all computers connect to a central switch.
A switch is a device that receives data and forwards it only to the intended destination device.
- Easy to add or remove computers
- If one cable fails, only one computer is affected
- Less cabling than a mesh network
- If the switch fails, the whole network stops working
- More expensive than a simple mesh network
3. Star Network with a File Server
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A file server is a powerful computer that stores files and user accounts.
In a school network, this allows students to:
- Log on to any computer
- Access their files from anywhere on the network
- Save work centrally rather than on one machine
The switch allows computers to communicate efficiently with the file server without sending data to every device.
4. Connecting the Network to the Internet (Using a Router)
star_network_w_router.gif)
A router connects a local network (LAN) to external networks, such as the internet.
When a computer wants to access a website:
- The data is sent to the switch
- The switch forwards it to the router
- The router sends the data to the internet
The router also ensures that incoming data from the internet is sent back to the correct computer.
5. How Web Data Travels Across the Internet (Packet Switching)
Internet_packet_switching.gif)
When a web page is requested from a web server, it is split into packets.
Each packet:
- Contains part of the data
- May take a different route through the internet
- Is routed independently by routers
Once all packets reach the client computer:
- They are reassembled
- Placed back into the correct order
- The web page is displayed correctly
This method is called packet switching and makes the internet fast, reliable, and fault tolerant.