2.3 Network Topologies
Network topology is the shape of how nodes connect. Bus, star, ring, mesh, tree, hybrid - each has trade-offs in cost, fault tolerance, and complexity.
2.3 Network Topologies
The six classical topologies
Trade-offs at a glance
| Topology | Cost | Fault tolerance | Typical scale |
|---|---|---|---|
| Bus | Low | Single break = down | Small |
| Star | Medium | Hub is SPoF | Medium |
| Ring | Medium | One-break tolerant | Medium |
| Mesh | High | Multi-break tolerant | Large |
| Tree | Medium | Branch isolation | Campus |
| Hybrid | Varies | Varies | Enterprise |
Enterprise patterns in practice
| Setting | Topology |
|---|---|
| Office LAN | Star (Ethernet to a switch in the IDF) |
| Campus WAN | Tree (HQ at root, buildings at branches) |
| Data centre | Leaf-spine mesh (modern fabric design) |
| Multi-site | Partial mesh + ISP redundancy |
Logical vs physical topology
Two networks can share a physical star but run different logical topologies (e.g. multiple VLANs that look like separate stars at L2). Document both - they answer different questions.
Mentor’s tip: Star for LANs, tree for campuses, mesh for data centre fabric. Document logical and physical topologies separately. The right topology is the one that meets your RTO/RPO at the lowest sustained cost.
Discussion
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