Networks & Protocols Grade 11
Building on Grade 10 networks — this page covers topologies, network devices in depth, protocols, VoIP, VPN and acceptable use.
Network Topologies
A network topology is the layout or "shape" of a network — it describes how the computers and devices are physically or logically arranged and connected to one another. The topology you choose affects how easy the network is to set up, how it copes with a fault, and how easy it is to add new devices later.
Star Topology
In a star topology every device connects to one central point — usually a switch. Nothing connects directly to anything else; all traffic passes through the middle.
Picture a bicycle wheel: the hub in the centre is the switch, and each spoke is a cable running out to one computer. If a single spoke breaks the rest of the wheel is fine — but if the hub itself fails, the whole wheel falls apart. That is exactly why a star network keeps working when one PC fails, yet goes completely down if the central switch fails.
| Topology | Layout | Advantages | Disadvantages |
|---|---|---|---|
| Star | All devices connect to a central switch | One failure doesn't affect others; easy to add devices | If switch fails, entire network fails |
| Ring | Devices in a closed loop | Equal opportunity to transmit; no collision | One break can down the whole network |
Ring Topology in Detail
In a ring topology, every device connects to exactly two neighbours, forming a closed loop. Data travels in a single direction around the ring, passing through each device in turn — every node acts as a repeater, regenerating the signal and passing it on to the next node until it reaches its destination.
| Advantages | Disadvantages |
|---|---|
| Organised and efficient — each node gets an equal opportunity to transmit, and one-way flow reduces data collisions | Single point of failure — one broken cable or dead device can bring the whole ring down (unless it's a dual-ring setup) |
| No central server required to control connectivity between workstations | Hard to troubleshoot — difficult to identify exactly where a fault occurred |
| Reliability depends on every single connection in the loop working |
Thin vs Thick Client
| Thin Client | Thick (Fat) Client | |
|---|---|---|
| Processing | Done mostly on server | Done on local computer |
| Storage | Minimal local storage | Large local storage |
| Cost | Cheaper | More expensive |
| Example | School lab PC connected to server | Personal desktop PC |
Key Protocols
| Protocol | Purpose |
|---|---|
| HTTP | Transfer web pages (unencrypted) |
| HTTPS | Secure web transfer (SSL/TLS encryption) |
| SMTP | Send emails |
| POP3 | Download emails to device |
| IMAP | Access emails online without downloading |
| FTP | Transfer large files between computers |
| VoIP | Voice calls over the Internet |
VoIP
Voice over Internet Protocol allows phone/video calls using the Internet instead of traditional phone lines.
Your voice is broken into tiny digital packets, sent across the internet just like any other data, and reassembled at the other end. Because it rides on your existing internet connection, calls to other VoIP users are usually free no matter how far away they are — which makes it far cheaper than a traditional long-distance phone call.
- Examples: WhatsApp calls, Skype, Discord, Zoom
- Requires: stable internet, low latency, sufficient bandwidth
VPN
A Virtual Private Network creates an encrypted "tunnel" over the Internet.
- Allows remote users to access a private network securely
- Hides IP address and encrypts all data in transit
- Used by companies for remote workers
Internet vs Intranet vs Extranet
| Network | Access | Description |
|---|---|---|
| Internet | Public | Global network open to all |
| Intranet | Private | Internal company/school network |
| Extranet | Controlled external | Intranet accessible from outside (VPN) |
Acceptable Use Policies (AUP)
Rules governing how ICT resources may be used in an organisation. Key rules:
- No downloading illegal content
- Use computers for educational/work purposes
- No cyberbullying or harassment
- Respect copyright laws