Star / Hub-and-Spoke - Learn Tech From Zero

1.6 Compare and contrast network topologies, architectures, and types

📘CompTIA Network+ (N10-009)

Star Topology / Hub-and-Spoke Topology

Definition

A star topology is a network design where all devices (computers, printers, servers, etc.) are connected to a central device called a hub, switch, or router.

In IT terms, the hub or switch acts as a central point for managing network traffic.
Data from one device always travels through the central device to reach other devices.

A hub-and-spoke topology is basically a wide-area network (WAN) version of a star.

Here, multiple branch offices (spokes) connect to a central office (hub).
The central hub manages traffic between all the spokes.

Structure / Diagram (Conceptually)

       Device A
          |
       Device B
          |
Central Hub/Switch/Router
          |
       Device C
          |
       Device D

For hub-and-spoke:

       Branch 1
          |
       Branch 2
          |
      Central Hub Office
          |
       Branch 3

Key Features

Centralized Management
- All devices connect to one central device.
- Easy to monitor and control network traffic from the hub or switch.
Simple to Add or Remove Devices
- Adding a new computer only requires a connection to the central device.
- Removing a device doesn’t affect the rest of the network.
Common Devices Used
- Switch – Most common today; can forward data only to the intended device (more efficient than a hub).
- Hub – Older technology; sends data to all devices (less efficient).
- Router – Can act as a hub in WAN scenarios.
Fault Isolation
- If one device fails, the rest of the network keeps working.
- If the central device fails, the whole network goes down.
Performance
- Good performance for smaller networks.
- Switches can reduce collisions using full-duplex communication.
- Performance may degrade if the hub is overloaded.

Advantages

Easy to manage and troubleshoot because all connections converge at a central point.
Flexible to expand; just plug in more devices.
Fault isolation is easier — problem in one device doesn’t affect others.
Compatible with modern networking hardware like Ethernet switches and routers.

Disadvantages

Single point of failure: If the central hub or switch fails, the whole network fails.
More cabling required because each device needs its own cable to the hub.
Cost can be higher for large networks due to cabling and the central device.

Use in IT Environments

LAN (Local Area Network)
- Offices often use a star topology.
- Example: Computers and printers in a floor connect to a central Ethernet switch.
WAN (Wide Area Network) – Hub-and-Spoke
- Branch offices connect to the main data center via a router (hub).
- Central office manages all communication, such as email, file access, or VPN connections.
Data Centers
- Core switches act as hubs connecting multiple servers.
- Provides high control over traffic flow between servers.
VPN Connections
- A central VPN server (hub) allows remote users (spokes) to securely connect to company resources.

Exam Tips

Remember the “central device” concept: All data goes through the hub/switch/router.
Fault tolerance: One device failing is okay; central device failing is critical.
Star = LAN; Hub-and-Spoke = WAN version of Star.
Know the difference between hub and switch: hub sends to all, switch sends to intended device only.
Common question: “Which topology isolates faults better?” → Star is preferred over bus.

✅ Quick Summary Table

Feature	Star Topology	Hub-and-Spoke Topology
Central Device	Hub/Switch/Router	Central Hub/Router
Device Failure Impact	Only failed device affected	Only failed branch affected; hub failure affects all
Scalability	Easy	Easy, but depends on hub capacity
Common Use	LAN	WAN (branch offices)
Cabling	Requires individual cables	Requires connection to central hub