A2.2.1 — Network Topologies
What is Network Topology?
The arrangement of devices (nodes) and connections (links) within a network. Can be physical (actual layout of cables and hardware) or logical (how data flows, regardless of physical arrangement).
Star Topology
- Structure: Each device connects directly to a central switch/hub. Star shape with central device at centre.
- Reliability: High — a single cable or device failure only isolates that device. If the central switch fails, the whole network fails.
- Speed: Generally fast. Direct connections reduce bottlenecks.
- Scalability: Easy — just connect to an available port. Limited by the number of ports on the central switch.
- Collisions: Rare — modern switches eliminate most collisions.
- Cost: Higher cabling cost — each device needs its own dedicated line to the centre.
- Examples: Home networks, business LANs with centralised managed switches.
Mesh Topology
- Structure: Devices connect directly to as many other nodes as possible. Full mesh = every node connected to every other. Partial mesh = some but not all.
- Reliability: Very high — if one node or connection fails, data is rerouted automatically. No single point of failure.
- Speed: Can be fast but depends on number of hops, connection strength, and traffic. (A hop = packet passing through one device to another.)
- Scalability: Easy — add a node, power it on, automatic configuration. Many mesh protocols handle this automatically.
- Collisions: Uncommon — intelligent routing algorithms find efficient paths.
- Cost: Varies — simple mesh affordable; enterprise-grade nodes expensive.
- Examples: Google Nest/Eero Wi-Fi mesh systems, community internet access, IoT sensor networks in manufacturing.
Hybrid Topology
A combination of two or more different topology types (e.g. star + mesh) to optimise performance, reliability, and scalability based on specific needs.
- Reliability: Very high — inherits the combined strengths of incorporated topologies. Multiple data paths ensure the network continues even if components fail.
- Speed: Varies by configuration. Direct connections (mesh-style) enhance speed in some segments; centralised elements streamline routing in others.
- Scalability: Flexible — can expand using the easier-to-scale component type (e.g. adding to the star portion).
- Cost: Can be high — more complex to implement and maintain than a single topology.
- Examples: Large corporate networks (star for central offices, mesh for peripheral devices), smart city infrastructure, complex enterprise environments.
Comparison
| Feature | Star | Mesh | Hybrid |
|---|---|---|---|
| Reliability | High (fails if switch fails) | Very high (no single failure point) | Very high |
| Speed | Fast | Variable (hops) | Variable |
| Scalability | Limited by switch ports | Easy, auto-config | Flexible |
| Cost | Higher cabling | Depends on nodes | High |
| Collisions | Rare | Uncommon | Varies |