Table of Contents
Introduction
In modern enterprise Wi-Fi, centralized authentication servers (e.g., RADIUS) are used to verify client access and guarantee safety. If the server fails—due to outage, downtime, or timeout—new users cannot be authenticated, causing service disruption.
To ensure continuity, AP Failover Authentication Escape allows clients to temporarily connect under controlled conditions when the authentication server is unavailable. The following sections describe its concept, operational workflow, and Asterfusion’s specific implementation.
What is AP Failover Authentication Escape
AP Failover Authentication Escape is an engineering feature developed by vendors, leveraging concepts from IEEE wireless standards (such as 802.11r, 802.11k, and 802.11v) to address the practical requirements of enterprise and campus networks. It ensures network continuity during authentication server failures. When the server becomes unavailable, this mechanism allows already authenticated roaming clients to maintain seamless access, ensuring uninterrupted service.
Its core objective is to balance network security with business continuity, enabling clients to access necessary resources in a controlled manner during outages.
Why AP Failover Authentication Escape
In enterprise and campus network environments, clients typically need to complete access authentication through an authentication server (using methods such as Portal or 802.1X), which is a critical step in ensuring network security. However, when the authentication server fails or becomes unavailable, clients cannot successfully authenticate and, consequently, cannot access network resources.
Specifically, the following issues may arise:
- Users cannot access the network: Clients fail authentication and are unable to reach network resources, making it difficult to meet normal network usage needs.
- Conflict between security and availability: Strict dependence on the authentication server makes it challenging to provide a secure temporary access path during server outages, creating a tension between security and availability.
- Business continuity risks: If clients cannot connect while roaming due to server issues, critical services may be interrupted, potentially causing significant losses.
- Degraded user experience: Temporary visitors or other user groups may be unable to access the network smoothly, negatively impacting overall network service experience.
Therefore, the AP Failover Escape Mode plays a crucial role in mitigating these issues, allowing the network to maintain controlled access even when the authentication server is unavailable.
How does It Work
- Trigger Conditions When a client connects to an AP but the authentication server (Portal or 802.1X) is unreachable or authentication fails, the AP detects that authentication cannot be completed and triggers the failover mechanism.
- Policy Evaluation The AP evaluates pre-configured policies to determine whether a client is allowed temporary access via the “escape channel.” Access through this channel is typically restricted, for example: only to specific business systems, only to certain Internet services, or subject to controlled bandwidth or QoS limitations.
- Temporary Authorization The AP assigns the client to a temporary VLAN, providing network isolation and secure access. VLANs or ACLs are used to ensure that temporarily authorized clients cannot access sensitive business systems.
- Recovery and Revocation Once the authentication server recovers or the client successfully completes standard authentication, the AP revokes the temporary access and restores the client to its original VLAN and policy settings, ensuring network policy consistency and security.
Process Flow Diagram
How does Asterfusion OpenWiFi AP do
The Asterfusion OpenWiFi AP Failover solution is designed to ensure that already-authenticated roaming clients can access critical network resources within a controlled scope even when the authentication server (Portal or RADIUS) fails, malfunctions, or becomes unreachable. The solution configures an escape VLAN on the controller side, and when the AP detects an authentication anomaly, it automatically switches to escape mode. Once the server recovers, the AP returns to normal operation, achieving a balance of high availability, business continuity, and secure isolation.
1. Detection and Trigger
Detection: Use the nc command to check whether the Portal server is functioning normally; or use simulated client authentication to check whether the RADIUS server is operational.
Trigger: If the server is unreachable for three consecutive checks, the AP switches wireless traffic from normal authentication mode to escape mode.
2.Deployment and Configuration
It is implemented centrally by the controller.
Administrators configure the escape VLAN policy on the Asterfusion OpenWiFi Network Controller, and the One-Click Push feature allows the escape configuration to be synchronized to all selected APs via wireless templates, enabling centralized and streamlined management.
3.Coordination with Switches:
If the access/leaf switches do not have the escape VLAN preconfigured, the controller can push the VLAN configuration to ensure end-to-end network consistency. It is recommended to verify that the escape VLAN exists on the switches before deployment, or configure it centrally via the controller, to prevent clients from being unable to obtain temporary access during exceptions.
For a step‑by‑step guide to configuring AP Failover Escape Mode, click here.
Key Q&A
Q: When searching for “AP Failover” online, many discussions mention setting AP failover priority. Why doesn’t the Asterfusion OpenWiFi controller provide this parameter? Was it overlooked?
A: Absolutely not. This is a common misunderstanding caused by comparing our controller with traditional AC-based architectures.
In a traditional centralized forwarding model, the controller (AC) not only manages APs but also forwards all user traffic. When the primary AC fails, APs must reconnect to a backup AC. If resources are limited, an AP failover priority is required to decide which APs should reconnect first.
In contrast, the Asterfusion OpenWiFi architecture uses a distributed forwarding model:
- The controller is only responsible for management, configuration, and policy distribution.
- Data forwarding is distributed
- If the controller becomes unavailable, APs continue forwarding traffic and enforcing existing policies without interruption.
Because user traffic is never dependent on the controller, there is no need for AP failover priority. This is not an omission but a deliberate design choice to improve scalability, reduce latency, and enhance overall network resilience.
Want to learn more about our OpenWiFi-based controller? Read the full article here.
Find out more about APs that arrive pre-loaded with OpenWiFi.
