RADIUS Server Status Alert

The RADIUS Server Status alert is generated when the reachability or operational status of a configured RADIUS server changes. This alert indicates that the network device is unable to successfully communicate with the RADIUS authentication server.

A RADIUS server status issue can impact client authentication, access control, and network onboarding until connectivity to the server is restored.

Figure 1: RADIUS Server Status Alert Sample

Alert Triggering and Clearing Conditions

  • Triggering Condition—The alert is triggered when the configured RADIUS server becomes unreachable, non-responsive, or its status changes to down based on connectivity checks.

  • Clearing Condition—The alert automatically clears when the RADIUS server becomes reachable and responsive again and successful communication is restored.

Common Causes

RADIUS server status issues may occur due to the following reasons:

  • RADIUS server unreachable due to network connectivity issues.

  • Incorrect server IP address or configuration.

  • Firewall blocking RADIUS ports (UDP 1812/1813).

  • Authentication server downtime or maintenance.

  • Routing or DNS resolution issues.

  • Incorrect shared secret configuration.

  • High latency or packet loss between device and RADIUS server.

Alert Behavior

When an RADIUS Server Status alert is triggered:

  • Classic Central detects the change in RADIUS server reachability or health.

  • The affected device and RADIUS server details are displayed in the alert view.

  • The system may run connectivity checks (such as ping) to validate server reachability.

  • Diagnostic insights and remediation guidance are provided in the Action and Troubleshooting sections.

Summary Card

The Summary card provides a concise overview of the alert, including:

  • Affected device and RADIUS server address.

  • Server status and reachability details.

  • Alert priority level, first occurred, last occurred, and duration.

  • Number of occurrences.

  • Firmware version and alert scope.

Impact Card

The Impact section indicates whether the event affects: clients, access points, network services using centralized authentication, and switches.

Action Card (Root Cause and Actions)

The Action card provides probable root causes and recommended remediation steps to restore RADIUS server reachability and authentication services.

  • Possible Root Causes:

    • There may be an IP connectivity issue between the switch and the RADIUS server.

    • The RADIUS service on the server may be experiencing issues, leading to failed or delayed authentication responses.

    • The RADIUS server may be overloaded or encountering high resource utilization (CPU or memory).

    • The RADIUS server may become unreachable, causing authentication failures for new clients.

  • Recommended Actions

    • Connectivity Issue—Check IP connectivity between the switch and the RADIUS server using PING or traceroute. Verify routing paths and network reachability to the server.

    • RADIUS Service Issues or Delayed Responses—Verify that the RADIUS service is running on the server. Check server resource usage (CPU and memory) and logs to identify overload, crashes, or error conditions. Ensure proper load distribution to avoid overloading a single RADIUS server. Implement load balancing across multiple RADIUS servers to distribute authentication requests.

    • RADIUS Server Unreachable— If the RADIUS server becomes unreachable, new client authentications and re-authentications may fail. Use authentication survivability mechanisms such as cached authentication and cached critical roles (if previously authenticated clients exist). Validate firewall rules, server availability, and network path stability to restore server reachability.

Troubleshooting Card

Provides quick diagnostics such as connectivity checks (for example, Ping Check to the RADIUS server). Displays test results indicating whether the server is reachable. Highlights high-level authentication or reachability issues. Includes an expand option for deeper diagnostics when available.

  • ORCA View (Expanded Diagnostics)

    Click the expand icon in the Troubleshooting card to view the ORCA tab. The ORCA provides detailed diagnostics that include:

    • Server reachability test results.

    • Device-to-server communication status.

    • Network path validation insights.

    • Identified root cause impacting authentication connectivity.

Related Events

The Events card displays related alert events such as, RADIUS server reachability changes, connectivity check failures, and status change timestamps.

Additional Notes

RADIUS Server Status alerts are generated per configured RADIUS server. Alerts automatically clear once server reachability is restored. Prolonged RADIUS outages may result in client authentication failures and access disruptions and should be resolved promptly.