Captive Portal Authentication Flow

J
Julien Robert, CTO

A network flow diagram for captive portal authentication in an educational institution — showing how student devices move through 802.1X/RADIUS authentication, dynamic VLAN assignment, and captive portal fallback. Two paths are modeled: authenticated devices go straight to the student VLAN; unauthenticated BYOD devices hit the quarantine VLAN and get redirected to the portal. Built for IT administrators and network architects who need to document or communicate their access control architecture.

How to create a Captive Portal Authentication Flow

To create a captive portal authentication flow, follow these steps:

01.
List the main components
Identify every network element: access points, switches, RADIUS server, firewall, Nginx frontend, backend API, VLANs.
02.
Define the two authentication paths
Path A: 802.1X credentials → RADIUS → student VLAN. Path B: BYOD → quarantine VLAN → captive portal.
03.
Organize with subgraphs
Group elements into labeled subgraphs: Network Access, Switch Authentication, Dynamic VLANs, Captive Portal, Internet.
04.
Model the decision point
After the firewall, use a diamond node to check for an active session. No session → redirect. Active session → internet access.
05.
Show the portal authentication flow
Redirect → Nginx → backend API → validation → session creation → redirect to internet.
06.
Add the RADIUS success path
Show how authenticated 802.1X traffic bypasses the portal and routes directly to the internet.
07.
Label edges
Annotate arrows with protocol and port details where relevant — this makes the diagram useful as actual reference documentation.

Share with others

Tags

Network ArchitectureAuthenticationCaptive Portal802.1XRADIUSVLANFlowchartIT InfrastructureEducation

You might also like

View all

System Architecture Block Diagram

Build high-level system layouts showing how components connect and interact. This template uses blocks and arrows to represent databases, services, modules, and their relationships — making complex architectures digestible at a glance. Ideal for technical documentation, architecture reviews, onboarding engineers, or planning system integrations.
M
Mermaid

Project Timeline Gantt Chart

Track project tasks, dependencies, and timelines in one visual schedule. This template shows what needs to happen when, helping teams coordinate work, spot scheduling conflicts, and keep stakeholders informed on progress. Essential for project planning, resource allocation, sprint planning, or communicating delivery timelines to clients.
M
Mermaid

Business Planning Mind Map

Organize every piece of your business strategy in one visual space. This template breaks down business planning into clear branches — from company profile and financials to market analysis and competitive positioning — making it easier to see how different aspects of your business connect. It’s a quick way to align stakeholders, prepare for investor meetings, or align your team around priorities.
M
Mermaid

System Mindmap Overview

Organize system concepts and relationships visually to improve understanding and brainstorming. This mindmap captures system origins, research, tools, and applications in a structured, scannable layout.
M
Mermaid