Class 12 Computer Network Network Topologies: Star, Bus, Tree, Mesh Part 2

Network topologies describe the arrangement of various elements (links, nodes, etc.) in a network. The choice of topology affects the network’s performance, scalability, and fault tolerance. Here’s a detailed overview of four common network topologies: Star, Bus, Tree, and Mesh.

1. Star Topology

Structure:

• Central Node: All devices (nodes) are connected to a central hub or switch.
• Connections: Each device has a direct connection to the central node.

Advantages:

• Ease of Installation: Adding or removing devices is simple and does not disrupt the network.
• Fault Isolation: If a single cable fails, only the affected device is impacted, not the entire network.
• Performance: The central hub/switch manages traffic efficiently, reducing collisions.

Disadvantages:

• Central Point of Failure: If the central hub or switch fails, the entire network is affected.
• Cost: Requires more cables and hardware (hubs/switches) compared to some other topologies.

Example:

• Home Network: In a typical home network, devices like computers, printers, and smart TVs are connected to a router (central node) using Ethernet cables or Wi-Fi.

2. Bus Topology

Structure:

• Single Central Cable: All devices are connected to a single central cable (the bus), which carries data in both directions.
• Terminators: The ends of the bus cable are terminated to prevent signal reflection.

Advantages:

• Cost-Effective: Requires less cabling compared to star topology.
• Simple Setup: Easy to implement in smaller networks.

Disadvantages:

• Fault Tolerance: A failure in the central cable affects the entire network.
• Performance Issues: As more devices are added, network performance can degrade due to increased collisions and traffic congestion.
• Troubleshooting: Difficult to isolate and troubleshoot issues on the bus.

Example:

• Legacy Networks: Older Ethernet networks (10BASE-2 or 10BASE-5) used a bus topology where devices were connected along a single coaxial cable.

3. Tree Topology

Structure:

• Hierarchical Structure: Combines elements of star and bus topologies. Multiple star networks are connected to a central bus, forming a tree-like structure.
• Branches: Devices are grouped in star-configured segments connected to a central backbone.

Advantages:

• Scalability: Easy to expand by adding new branches or segments.
• Fault Isolation: Problems in one segment do not necessarily affect other segments.
• Hierarchical Management: Facilitates management and organization of larger networks.

Disadvantages:

• Complexity: More complex to design and manage compared to simpler topologies.
• Central Backbone: If the central backbone fails, it can affect multiple segments.

Example:

• Corporate Networks: Large organizations often use tree topology to connect different departments or buildings, each with its own star-configured network.

4. Mesh Topology

Structure:

• Direct Connections: Each device is connected to every other device in the network, forming a mesh of interconnections.
• Full Mesh vs. Partial Mesh: In a full mesh, every device is connected to every other device. In a partial mesh, some devices are connected to all others, while others are connected to only a subset.

Advantages:

• Fault Tolerance: High fault tolerance because multiple paths exist for data transmission. If one connection fails, data can be routed through other connections.
• Reliability: Provides redundancy and high reliability, making it ideal for mission-critical applications.

Disadvantages:

• Cost: Requires a large amount of cabling and network interfaces, making it more expensive.
• Complexity: Complex to set up and manage due to the large number of connections.

Example:

• Internet Backbone: The internet itself is a form of mesh network where various data centers and routers are interconnected, ensuring that data can be rerouted if one path fails.

Summary

• Star Topology: Devices connected to a central hub or switch; easy to manage and scale but reliant on the central node.
• Bus Topology: Devices connected to a single central cable; cost-effective but can suffer from performance issues and is sensitive to cable failures.
• Tree Topology: Hierarchical structure with multiple star networks connected to a central backbone; scalable and fault-tolerant but complex and reliant on the backbone.
• Mesh Topology: Devices interconnected directly; highly reliable and fault-tolerant but expensive and complex.