Question

Distinguish between the following LAN topologies: ring, star, and bus.

Short answer

Ring topology connects in a circle, star uses a central hub, and bus shares a single communication line.

Step-by-step solution

Understand Ring Topology

In a ring topology, each computer is connected to two other computers, forming a circular pathway for signals. Data travels in one direction around the circle, passing through each node until it reaches its destination. This setup can make data transfer relatively efficient, but if one node fails, it can disrupt the entire network unless there are redundancies like a dual ring.

Understand Star Topology

In a star topology, all computers are connected individually to a central hub or switch. The hub acts as a repeater for data flow. It is easy to install and manage, and provides better fault tolerance (as a failure in one cable does not affect others). However, if the central hub fails, the whole network becomes inoperative.

Understand Bus Topology

In a bus topology, all devices share a single communication line or cable called a bus. Data from one computer is sent along the bus line in both directions for all other nodes to see, but only the addressed node will accept and process the data. It is a straightforward setup and inexpensive but can become slow with many devices and is prone to network failure if the main cable fails.

Compare and Contrast

All three topologies have unique characteristics: - A ring topology is efficient but sensitive to node failures. - A star topology has better fault tolerance but depends heavily on the central hub. - A bus topology is simple and cost-effective but not suitable for large or busy networks.

Key concepts

Ring Topology

In a ring topology, each computer (or node) is linked to exactly two others, forming a circular data path. This means data transmissions move sequentially from one node to the next, following the circle until they reach their destination. A significant advantage of this setup is the predictable data transfer time, as each node handles data traffic in turn. However, one crucial downside is that if any node in the circle is faulty, it can disrupt the entire network.
Fortunately, there are solutions to mitigate this risk, such as implementing a dual ring topology, where two rings are employed. This provides an alternative path for data in case one node fails, enhancing network reliability. Overall, while ring topology can be efficient and beneficial in specific scenarios, its potential for a single point of failure requires careful management.

Star Topology

In a star topology, each computer connects to a central hub or switch, creating a network layout that resembles a star. This central hub acts like an exchange, directing traffic from a sender to its intended recipient. One of the main benefits of star topology is its robustness. Since each node connects independently to the central hub, a failure in one connection typically doesn't impact others.
However, the network's efficiency heavily relies on the hub itself. If the hub or switch crashes, the entire network can become non-functional, highlighting the importance of a reliable central component. This setup is popular because adding or removing devices is straightforward, making it scalable and easy to manage. To sum up, star topology offers excellent scalability and ease of troubleshooting, as long as the central hub remains operational.

Bus Topology

A bus topology features all devices connected to a singular communication line, known as the bus. Every device on the network listens for data traveling along the bus and only processes messages intended for it. The simplicity of bus topology is a compelling advantage. It uses less cabling and is easy to set up initially, making it a cost-effective option for smaller networks.

• The network runs data in both directions along the single-tier cable.
• Each device communicates over the same bus, meaning overloading the network can slow down performance.

While low in cost, bus topology may not suffice for sophisticated networks with heavy traffic since it can get congested. Moreover, it shares a vulnerability; if the central cable fails, the entire network can be compromised. Thus, bus topology is best suited for smaller networks where high data transmission speed is not a priority.