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This lesson covers the three network topologies you need to know for OCR J277 Section 1.3.1: star, mesh, and bus. A topology describes the physical or logical arrangement of devices in a network.
A network topology is the layout or structure describing how devices (nodes) in a network are arranged and connected. The topology affects the network's performance, reliability, cost, and ease of maintenance.
In a star topology, all devices are connected to a central device (usually a switch or hub). Devices do not connect directly to each other — all communication passes through the central device.
[PC1]
|
[PC2]--[SWITCH]--[PC3]
|
[PC4]
| Advantage | Explanation |
|---|---|
| Easy to add/remove devices | New devices can be connected without disrupting the network |
| Fault isolation | If one cable or device fails, only that device is affected; the rest of the network continues working |
| Good performance | The switch sends data only to the intended recipient, reducing unnecessary traffic |
| Easy to troubleshoot | Faults can be identified and fixed quickly |
| Disadvantage | Explanation |
|---|---|
| Central point of failure | If the switch/hub fails, the entire network goes down |
| More cabling | Each device needs its own cable to the central device, increasing cost |
| Cost | The central switch/hub adds to the cost |
In a mesh topology, devices are connected to multiple other devices. There are two types:
| Type | Description |
|---|---|
| Full mesh | Every device is connected directly to every other device |
| Partial mesh | Some devices are connected to all others, but some are only connected to a few |
Full Mesh (4 devices):
[PC1]---[PC2]
| \ / |
| \ / |
| X |
| / \ |
| / \ |
[PC3]---[PC4]
| Advantage | Explanation |
|---|---|
| No single point of failure | If one connection fails, alternative paths exist |
| High reliability | Multiple routes mean the network can tolerate faults |
| Data can be transmitted simultaneously | Multiple paths allow parallel data transmission |
| Good for critical systems | Used where downtime is unacceptable |
| Disadvantage | Explanation |
|---|---|
| Expensive | Requires many cables and network interfaces |
| Complex | Difficult to set up and manage |
| Impractical for large networks | The number of connections grows rapidly as devices are added |
| Maintenance | More connections mean more to maintain and troubleshoot |
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