Network topologies (star, bus, ring, mesh) in Computer Networks - Mini Project: Build & Apply

Understanding Network Topologies

📖 Scenario: You are setting up a small office network. You want to understand different ways computers can be connected to share information efficiently and reliably.

🎯 Goal: Build a simple representation of four common network topologies: star, bus, ring, and mesh. You will create data structures that show how devices connect in each topology.

📋 What You'll Learn

Create a dictionary named devices with exactly four devices named 'PC1', 'PC2', 'PC3', and 'PC4'.

Create a variable named central_hub with the value 'Switch' to represent the central device in the star topology.

Create a dictionary named topologies that maps each topology name ('star', 'bus', 'ring', and 'mesh') to a list of connections representing how devices are linked.

Add a final variable named description with a short explanation string about the star topology.

💡 Why This Matters

🌍 Real World

Understanding network topologies helps in designing and troubleshooting computer networks in offices, schools, and homes.

💼 Career

Network administrators and IT professionals use knowledge of topologies to plan efficient and reliable network layouts.

1

Create the devices dictionary

Create a dictionary called devices with these exact keys and values: 'PC1': 'Computer 1', 'PC2': 'Computer 2', 'PC3': 'Computer 3', and 'PC4': 'Computer 4'.

Computer Networks

# Create the devices dictionary with four computers
# Your code here

Hint

Use curly braces {} to create a dictionary with the given keys and values.

2

Add the central hub variable

Create a variable called central_hub and set it to the string 'Switch' to represent the central device in the star topology.

Computer Networks

devices = {
    'PC1': 'Computer 1',
    'PC2': 'Computer 2',
    'PC3': 'Computer 3',
    'PC4': 'Computer 4'
}

# Create the central hub variable
# Your code here

Hint

Assign the string 'Switch' to the variable central_hub.

3

Define the topologies dictionary

Create a dictionary called topologies with these keys: 'star', 'bus', 'ring', and 'mesh'. Each key should map to a list of tuples showing connections between devices. Use the following connections exactly:

'star': connect each device to central_hub (e.g., ('PC1', central_hub))
'bus': connect devices in a line: ('PC1', 'PC2'), ('PC2', 'PC3'), ('PC3', 'PC4')
'ring': connect devices in a circle: ('PC1', 'PC2'), ('PC2', 'PC3'), ('PC3', 'PC4'), ('PC4', 'PC1')
'mesh': connect every device to every other device (all pairs).

Computer Networks

devices = {
    'PC1': 'Computer 1',
    'PC2': 'Computer 2',
    'PC3': 'Computer 3',
    'PC4': 'Computer 4'
}

central_hub = 'Switch'

# Create the topologies dictionary with connections
# Your code here

Hint

Use lists of tuples to represent connections. For mesh, list all unique pairs of devices.

4

Add a description for the star topology

Create a variable called description and set it to the string 'In a star topology, all devices connect to a central hub.' to explain the star network.

Computer Networks

devices = {
    'PC1': 'Computer 1',
    'PC2': 'Computer 2',
    'PC3': 'Computer 3',
    'PC4': 'Computer 4'
}

central_hub = 'Switch'

topologies = {
    'star': [('PC1', central_hub), ('PC2', central_hub), ('PC3', central_hub), ('PC4', central_hub)],
    'bus': [('PC1', 'PC2'), ('PC2', 'PC3'), ('PC3', 'PC4')],
    'ring': [('PC1', 'PC2'), ('PC2', 'PC3'), ('PC3', 'PC4'), ('PC4', 'PC1')],
    'mesh': [
        ('PC1', 'PC2'), ('PC1', 'PC3'), ('PC1', 'PC4'),
        ('PC2', 'PC3'), ('PC2', 'PC4'),
        ('PC3', 'PC4')
    ]
}

# Add a description of the star topology
# Your code here

Hint

Assign the exact string to the variable description.

Practice

1. Which network topology connects all devices to a single central device like a switch or hub?

easy

A. Bus topology

B. Star topology

C. Ring topology

D. Mesh topology

Solution

1. Step 1: Understand the central device concept

   Star topology connects all devices to one central device, which manages communication.

2. Step 2: Compare with other topologies

   Bus uses a single cable, ring connects devices in a circle, mesh connects devices directly to many others.

3. Final Answer:

   Star topology -> Option B

4. Quick Check:

   Central device = Star topology [OK]

Hint: Central device means star topology [OK]

Common Mistakes:

• Confusing bus with star because both use cables
• Thinking ring has a central device
• Mixing mesh with star due to multiple connections

2. Which of the following is the correct description of a bus topology?

easy

A. Devices connected in a closed loop

B. Devices connected to a central hub

C. All devices connected to a single cable

D. Each device connected to every other device

Solution

1. Step 1: Recall bus topology structure

   Bus topology connects all devices along a single communication cable.

2. Step 2: Eliminate other options

   Closed loop is ring, every device connected is mesh, central hub is star.

3. Final Answer:

   All devices connected to a single cable -> Option C

4. Quick Check:

   Single cable = Bus topology [OK]

Hint: Bus means one main cable for all devices [OK]

Common Mistakes:

• Confusing ring (closed loop) with bus
• Thinking mesh is a single cable
• Mixing star's central hub with bus

3. In a ring topology with 5 devices, if one device fails, what happens to the network communication?

medium

A. Communication switches to a central hub

B. Only the failed device loses connection

C. Communication continues normally

D. The entire network communication is disrupted

Solution

1. Step 1: Understand ring topology communication

   Devices are connected in a closed loop; data passes through each device.

2. Step 2: Analyze failure impact

   If one device fails, the loop breaks, stopping communication for all devices.

3. Final Answer:

   The entire network communication is disrupted -> Option D

4. Quick Check:

   One failure breaks ring loop = disruption [OK]

Hint: Ring breaks if one device fails [OK]

Common Mistakes:

• Assuming only failed device loses connection
• Thinking ring has a backup path like mesh
• Confusing with star topology behavior

4. A network uses a mesh topology but experiences frequent data collisions. What is the most likely cause?

medium

A. There is no central device to control traffic

B. Devices are connected in a ring causing loops

C. Devices are connected in a single cable

D. Only one device is connected to the network

Solution

1. Step 1: Understand mesh topology traffic

   Mesh connects devices directly; without control, many devices send data simultaneously.

2. Step 2: Identify cause of collisions

   Without a central controller or protocol, data packets collide causing errors.

3. Final Answer:

   There is no central device to control traffic -> Option A

4. Quick Check:

   No traffic control = collisions in mesh [OK]

Hint: No controller causes collisions in mesh [OK]

Common Mistakes:

• Confusing mesh with bus single cable
• Thinking ring causes collisions here
• Assuming one device can't cause collisions

5. A company wants a network where each device connects to every other device directly for maximum reliability. Which topology should they choose and why?

hard

A. Mesh, because every device connects directly to all others

B. Star, because it uses a central hub for easy management

C. Bus, because it uses a single cable to connect all devices

D. Ring, because devices form a closed loop for data flow

Solution

1. Step 1: Identify topology with direct device-to-device connections

   Mesh topology connects every device directly to all others, ensuring reliability.

2. Step 2: Compare other topologies for reliability

   Star depends on central hub, bus uses one cable, ring forms a loop but not all direct connections.

3. Final Answer:

   Mesh, because every device connects directly to all others -> Option A

4. Quick Check:

   Direct connections = Mesh topology [OK]

Hint: Direct all-to-all connections mean mesh [OK]

Common Mistakes:

• Choosing star for reliability ignoring central point failure
• Thinking bus provides direct connections
• Confusing ring loop with full direct connections