ITC Lesson 10 Notes | Network Topologies

L10

Lesson overview

What is a network topology

A network topology describes how computers and devices are arranged and connected in a network. It shows the pattern of cables, switches, and devices and how data travels between them. Choosing the right topology affects how easy it is to expand the network, how much it costs, and how the network behaves when there is a problem.

In local area networks inside schools or offices, common topologies include star, bus, ring, and mesh. Many modern networks also use a mix of these patterns in a hybrid design.

Star topology

In a star topology, all devices connect to a central device such as a switch or hub. Each computer has its own cable that goes directly to the center.

Advantages:

Easy to add or remove devices without affecting the rest of the network.
Problems in one cable usually do not bring down the entire network.
Issues are easier to locate because each device connects through the central point.

The main disadvantage is that if the central switch or hub fails, the whole network stops working.

Bus topology

In a bus topology, all devices share a single main cable called the backbone. Each computer taps into this cable to send and receive data.

Advantages:

Uses less cable compared to a star topology.
Can be cheaper and simpler in very small networks.

However, if the main cable fails, the entire network goes down. Performance can also slow down as more devices share the same bus and collisions increase.

Ring topology

In a ring topology, each device connects to exactly two neighbors, forming a closed loop. Data travels around the ring from one device to the next.

Advantages:

Data can flow in an orderly way around the ring.
Sometimes easier to predict network performance compared to a shared bus.

One major drawback is that if a single connection in the ring breaks, the whole network can be affected, unless there is a backup path.

Mesh topology

In a mesh topology, devices are connected by multiple paths. In a full mesh, every device connects directly to every other device. In a partial mesh, only some devices have multiple connections.

Advantages:

Very high reliability because there are alternate paths for data.
Network can continue to work even if one link fails.

The downside is that mesh networks can be expensive and complex to set up because they require more cabling and network interfaces.

Choosing a topology

In practice, network designers mix different topologies to balance cost, performance, and reliability. Star is popular for modern LANs, while mesh is common in critical backbone networks where uptime is very important.

Bus and ring for simple or older networks → Star for typical LANs → Mesh for high reliability

Lesson 10

Quick reviewer

Common network topologies and when to use them.

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Lesson 10 Cheat Sheet

Short lines you can reuse in quizzes and IDs.

L10 · Reviewer

Network topology
The physical or logical layout of devices and cables in a network and the path that data follows.
Star topology
All devices connect to a central switch or hub. Easy to manage and expand. One cable failure usually affects only one device, but the central device is a single point of failure.
Bus topology
All devices share a single main cable. Uses less cable but one backbone failure can take down the whole network and performance drops as more devices join.
Ring topology
Each device connects to two neighbors in a loop. Data travels around the ring. Failure of one link can stop communication unless there is a backup path.
Mesh topology
Devices have multiple paths between them. Very reliable but more expensive and complex because it needs more cabling and interfaces.
One sentence answer
“Network topologies such as star, bus, ring, and mesh describe how devices are arranged and each has its own trade off between cost, performance, and reliability.”