Network Topologies | Star, Bus, Tree & Mesh Topology | Complete Notes | CBSE Class 12 Informatics Practices (2026–27)
Class 12 · Informatics Practices
Network Topologies | Star, Bus, Tree & Mesh Topology
The physical or logical arrangement of computers and networking devices in a network is known as its Network Topology. The choice of topology affects the performance, reliability, maintenance, and cost of a network.
Different organizations use different topologies depending on the number of devices, available budget, and communication requirements.
What is Network Topology?
A Network Topology is the layout or structure in which computers, servers, switches, routers, and other networking devices are connected to each other in a computer network.
Why is Network Topology Important?
- Determines how devices communicate.
- Affects network performance and speed.
- Influences installation and maintenance costs.
- Improves fault detection and troubleshooting.
- Determines network scalability and reliability.
Types of Network Topologies
The CBSE Class 12 Informatics Practices syllabus includes the following network topologies:
- Star Topology
- Bus Topology
- Tree Topology
- Mesh Topology
1. Star Topology
In a Star Topology, every device is connected to a central device such as a switch or hub. All communication passes through this central device.
Simple Diagram
Computer
|
Computer --- Switch --- Computer
|
Computer
Advantages
- Easy to install and manage.
- Failure of one cable does not affect the entire network.
- Easy to detect faults.
- High performance in modern LANs.
Disadvantages
- Requires more cabling.
- If the central switch fails, the entire network stops working.
- Higher installation cost than Bus topology.
Examples
- School computer laboratories.
- Office LANs.
- Home Ethernet networks.
2. Bus Topology
In a Bus Topology, all computers are connected to a single communication cable called the backbone cable.
Simple Diagram
Computer ─── Computer ─── Computer ─── Computer
(Single Backbone Cable)
Advantages
- Simple and inexpensive.
- Requires less cable.
- Suitable for small networks.
Disadvantages
- If the backbone cable fails, the entire network fails.
- Difficult to identify faults.
- Performance decreases as more devices are added.
Examples
- Small office networks.
- Temporary networks.
3. Tree Topology
A Tree Topology combines the characteristics of Star and Bus topologies. It has a hierarchical structure with a root node and multiple levels of connected devices.
Simple Diagram
Main Switch
/ \
Switch A Switch B
/ \ / \
PC1 PC2 PC3 PC4
Advantages
- Easy to expand.
- Supports large networks.
- Faults can often be isolated to a branch.
Disadvantages
- Complex installation.
- Higher maintenance cost.
- Failure of the main backbone affects connected branches.
Examples
- University campuses.
- Large corporate offices.
- Government organizations.
4. Mesh Topology
In a Mesh Topology, every device is directly connected to every other device through dedicated communication links.
Simple Diagram
PC1 -------- PC2
|\ /|
| \ / |
| \ / |
| \ / |
| \ / |
| \/ |
| /\ |
| / \ |
| / \ |
| / \ |
| / \ |
PC3 -------- PC4
Advantages
- Highly reliable.
- No single point of failure between devices.
- Fast communication through dedicated links.
- Excellent security.
Disadvantages
- Very expensive.
- Requires a large number of cables.
- Difficult to install and maintain.
Examples
- Military communication systems.
- Data centers.
- Critical banking networks.
Comparison of Network Topologies
| Feature | Star | Bus | Tree | Mesh |
|---|---|---|---|---|
| Structure | Central device | Single backbone cable | Hierarchical | Every device connected to every other device |
| Installation Cost | Medium | Low | High | Very High |
| Reliability | High | Low | High | Very High |
| Scalability | Easy | Limited | Excellent | Difficult |
| Common Use | Schools & Offices | Small Networks | Large Organizations | Critical Systems |
Real-Life Applications
| Topology | Application |
|---|---|
| Star | School computer labs, offices, homes |
| Bus | Small temporary networks |
| Tree | Universities and corporate campuses |
| Mesh | Military, banking, and data centers |
Common Errors
| Mistake | Correct Concept |
|---|---|
| Star topology does not use a central device. | Star topology always uses a central switch or hub. |
| Bus topology has multiple backbone cables. | Bus topology uses a single backbone cable. |
| Mesh topology is inexpensive. | Mesh topology is the most expensive due to dedicated links. |
| Tree topology is suitable only for small networks. | Tree topology is designed for large, hierarchical networks. |
Quick Revision
| Topology | Key Feature | Best Example |
|---|---|---|
| Star | Central switch/hub | School LAN |
| Bus | Single backbone cable | Small office |
| Tree | Hierarchical structure | University campus |
| Mesh | Dedicated links between devices | Data center |
CBSE Exam Tips
- Remember that Star Topology uses a central switch or hub.
- Bus Topology uses a single backbone cable.
- Tree Topology combines the features of Star and Bus topologies.
- Mesh Topology provides the highest reliability but is also the most expensive.
- Practice comparison-based questions, as they are commonly asked in CBSE examinations.
Summary
A network topology defines how devices are connected in a computer network. The CBSE Class 12 Informatics Practices syllabus covers four important topologies: Star, Bus, Tree, and Mesh. Each topology has its own advantages, disadvantages, cost, and applications. Choosing the appropriate topology depends on the size, budget, and reliability requirements of the network.