Star Topology Diagram Code Example - Network Topology Guide

Most network engineers and students working on network diagrams eventually need a quick, reliable way to build a star topology layout using code. Whether you're documenting a small office network or creating a teaching resource, having a working star topology diagram code example saves hours of guesswork. This article gives you exactly that real code samples, clear explanations, and practical guidance you can use right away.

What Does a Star Topology Diagram Actually Look Like?

A star topology connects every device (called a node or endpoint) to one central device usually a switch or hub. If you picture a bicycle wheel, the hub in the center is your switch, and each spoke is a cable running to a computer, printer, or server. No device connects directly to another. All traffic passes through that central point.

This layout is one of the most common network topology codes and symbols you'll encounter in both home and enterprise setups. It's simple, easy to troubleshoot, and scales predictably.

How Do You Draw a Star Topology Diagram with Code?

You have several options depending on your tools and comfort level. Below are three practical approaches with working examples.

Using Python with NetworkX and Matplotlib

This is a popular choice for anyone comfortable with Python. NetworkX handles graph structures, and Matplotlib renders the image.

Code example:

import networkx as nx import matplotlib.pyplot as plt G = nx.Graph() central = "Switch" nodes = ["PC1", "PC2", "PC3", "PC4", "Printer", "Server"] for node in nodes: G.add_edge(central, node) pos = nx.shell_layout(G) nx.draw(G, pos, with_labels=True, node_color='skyblue', node_size=2000, font_size=10, font_weight='bold', edge_color='gray', width=2) plt.title("Star Topology Diagram") plt.show()

This produces a clean visual where the switch sits in the center and all other devices radiate outward. You can customize node colors, labels, and sizes to match your documentation style.

Using Mermaid.js for Web-Based Diagrams

If you're embedding diagrams in documentation, wikis, or markdown files, Mermaid.js is lightweight and easy to read.

Code example:

graph TD SW[Switch] --- PC1[PC 1] SW --- PC2[PC 2] SW --- PC3[PC 3] SW --- PC4[PC 4] SW --- PR[Printer] SW --- SRV[Server]

Mermaid renders this directly in many platforms including GitHub, Notion, and VS Code extensions. It's one of the fastest ways to generate a readable network topology diagram using codes without installing extra software.

Using Graphviz (DOT Language)

Graphviz is a tried-and-true tool for generating graph images from plain text descriptions.

Code example:

graph star { layout=neato node [shape=box, style=filled, fillcolor=lightblue] Switch [shape=circle, fillcolor=yellow] Switch -- PC1 Switch -- PC2 Switch -- PC3 Switch -- PC4 Switch -- Printer Switch -- Server }

Save this as star.dot and run dot -Tpng star.dot -o star.png to generate an image file. Graphviz gives you tight control over layout and styling.

Why Would You Use Code Instead of a Drawing Tool?

Manual tools like Visio or draw.io work fine for one-off diagrams. But code-based diagrams offer clear advantages in specific situations:

Version control You can track changes in Git just like any other file.
Reproducibility Anyone on your team can regenerate the same diagram from the same code.
Automation You can generate diagrams from live network inventory data using scripts.
Consistency Templates ensure every diagram in your documentation looks uniform.

If your team already uses standardized network topology symbols, code-based diagrams make it easier to enforce those standards across all documentation.

What Are Common Mistakes When Writing Star Topology Code?

A few issues come up regularly, especially for beginners:

Forgetting the central node Without defining a hub or switch node first, your edges have nothing to connect to.
Using directed edges in an undirected graph Star topologies are symmetric. Using DiGraph in NetworkX or digraph in Graphviz adds unnecessary arrow directions that misrepresent the layout.
Overcrowding the diagram If your star has 30+ nodes, the diagram gets hard to read. Consider splitting into sub-diagrams or using a hierarchical layout.
Ignoring labels Unlabeled nodes make diagrams useless for documentation. Always include meaningful device names or IP addresses.

How Do You Add Labels and IP Addresses to Your Diagram?

In the Python example above, you can replace plain device names with IP-labeled strings:

nodes = ["PC1\n192.168.1.10", "PC2\n192.168.1.11", "Printer\n192.168.1.50"]

In Mermaid, use the bracket syntax to add detail:

PC1[PC 1 - 192.168.1.10]

This level of detail is especially useful when your diagram serves as a quick reference during troubleshooting or when handing off network documentation to another team member.

Can You Code a Star Topology Diagram for a Network Simulation?

Yes. Tools like GNS3 and Cisco Packet Tracer let you define star topologies in simulation environments using their own scripting or drag-and-drop interfaces. For programmatic network simulations, Python libraries like Mininet allow you to script a star topology and test traffic behavior between nodes.

This overlaps with broader network diagram coding methods, where the same principles apply define nodes, define connections, render or simulate.

Quick Checklist Before You Publish Your Diagram

Central device (switch or hub) is clearly labeled and positioned at the center.
All peripheral nodes are connected only to the central device no direct node-to-node links.
Every node has a meaningful label (device name, IP, or both).
You used undirected edges, not directed ones.
The diagram is readable at the size you plan to display it.
You tested the code and confirmed it renders without errors.
You saved or exported the output in a format your team can use (PNG, SVG, PDF).

Start with the Python or Mermaid example above, swap in your own device names and IPs, and you'll have a working star topology diagram in under five minutes.