📚 Knowledge Library — Topic 3.10B — Hardware

Routers & Network Hardware

Understand how routers direct data packets, connect networks together, and assign IP addresses to devices.

Start LearningWorked Example
1. Invitation

Networks need traffic directors.

When data travels across a network, it does not move randomly.

A router helps data packets move towards the correct destination.

💡 Remember: routers help packets find their way through a network.
Figure 1.1
Network Traffic
Device
→
Router
→
Destination
2. Big Idea

A router chooses where packets go next.

A router reads the destination IP address in a packet header.

It then sends the packet towards its destination using a suitable path.

💡 A router does not read the message. It uses the address to move the packet on.
Figure 2.1
Router Decision
Packet header
↓
Destination IP
↓
Choose path
3. FutureLogic Bridge

Think of a hotel receptionist.

A hotel receptionist gives guests room numbers and directs them where to go.

A router does something similar on a network. It gives devices IP addresses and directs packets to the correct destination.

💡 Bridge: router = receptionist for network traffic.
Figure 3.1
Receptionist Model
Guest arrives
↓
Room number assigned
↓
Directed to room
4. Worked Example

A laptop joins a home network.

When a laptop connects to Wi-Fi, the router can assign it an IP address.

When the laptop sends or receives data, the router helps direct packets between the home network and the wider internet.

Simple home network

Laptop
needs address
Router
assigns IP
Internet
packets routed
The router connects the home network to other networks.
Figure 4.1
Home Router
Laptop
↔
Router
↔
Internet
5. Connecting Networks

Routers join networks together.

A router can connect a local network to another network, such as the internet.

This is why home routers allow phones, laptops and tablets to communicate beyond the home.

💡 Key idea: routers connect networks, not just individual devices.
Figure 5.1
Network to Network
Home network
↔
Router
↔
Internet
6. Exam Tip

Router assigns IP addresses, not MAC addresses.

A router can assign IP addresses to devices on a network.

A MAC address is different. It is assigned by the manufacturer of the network hardware.

🎯 Exam Tip: router assigns IP address. Manufacturer assigns MAC address.
Figure 6.1
Do Not Mix These Up
Router
= IP address

Manufacturer
= MAC address
7. Common Mistake

Replace vague answers with precise ones.

In packet switching questions, Cambridge often wants the router's specific job.

A general answer may be true, but it may not answer the question.

⚠️ Common Mistake:

Student answer: “A router connects devices.”

❌ Too vague for packet switching.

Better answer: A router directs data packets towards their destination by choosing a suitable route.
Figure 7.1
Packet-Switching Answer
Weak answer
connects devices

↓

Better answer
directs packets
chooses route
8. Summary

Routers in one screen.

A router directs data packets towards their destination using the destination IP address.

Routers connect networks together and can assign IP addresses to devices on a network.

Routers do not assign MAC addresses. MAC addresses are assigned by the manufacturer.

💡 Router = packet pathfinder and network connector.
Figure 8.1
Router Summary
Connect networks
Route packets
Assign IP addresses

Not MAC addresses