📡 Network Topologies

What is a Network Topology?

A network topology describes the physical or logical arrangement of devices and links in a network. It defines how devices are connected and how data flows.

Common Topologies

1. Point‑to‑Point

A direct link between two devices. Simple, low latency, but limited scalability.

Device A ─────────── Device B

2. Bus Topology (Legacy)

All devices share a single communication line (backbone). Terminators at ends absorb signals. Inefficient because collisions are common; rarely used today.

     ┌────┐  ┌────┐  ┌────┐
     │ A  │  │ B  │  │ C  │
     └─┬──┘  └─┬──┘  └─┬──┘
       └───────┼───────┘
            Backbone (Coaxial)

3. Star Topology (Hub‑and‑Spoke)

All devices connect to a central device (hub or switch). Easy to install and manage; failure of one device does not affect others, but central device is a single point of failure.

        ┌────┐
        │Hub/│
        │Sw  │
        └─┬──┘
    ┌─────┼─────┬─────┐
    │     │     │     │
 ┌─┴──┐ ┌┴───┐┌┴───┐┌┴───┐
 │ A  │ │ B  ││ C  ││ D  │
 └────┘ └────┘└────┘└────┘

4. Extended Star

Multiple star networks connected by a backbone switch. Common in larger buildings or campuses.

        Central Switch
           ┌───┴───┐
        Switch1   Switch2
        ┌─┼─┐     ┌─┼─┐
        A B C     D E F

5. Full Mesh

Every device has a direct link to every other device. Highest redundancy and fault tolerance, but expensive and hard to scale.

    A ───── B
    │＼    ／│
    │  ＼／  │
    │  ／＼  │
    │／    ＼│
    C ───── D

6. Partial Mesh

Some devices are interconnected, but not all. Balances cost and redundancy.

    A ───── B
     ＼     ／
      ＼   ／
       ＼ ／
        C

Practical Considerations

• Star is most common in modern LANs because of ease of troubleshooting and scalability.
• Full mesh is used in backbone networks or critical links (e.g., between core routers).
• In medical environments, redundancy is often required; extended star with redundant links is typical.