5.3.6 Dead interval function of RADIUS servers communication

If the switch does not receive a response from a RADIUS server, it will use other RADIUS servers for a period specified by the authentication radius-server dead-interval configuration command. The initial RADIUS server resumes authentication after this interval. If all RADIUS servers are unresponsive, authentication will fail for the duration of the period specified by the authentication radius-server dead-interval configuration command, even if communication is restored within the dead interval. To restore the RADIUS servers to active status, execute the following operation commands:

• Web authentication: clear web-authentication dead-interval-timer

• MAC-based authentication: clear mac-authentication dead-interval-timer

The figure below illustrates how the dead interval functionality works with RADIUS servers.

Figure 5-7: Dead interval function of RADIUS servers communication

The following table describes which Layer 2 authentication types support the use of a dead interval with RADIUS servers.

Table 5-21: Dead-interval of RADIUS server-based communication and support for Layer 2 authentication

Functionality	IEEE802.1X			Web Authentication			MAC-based Authentication
	Port-based authentication	VLAN-based authentication (static)	VLAN-based authentication (dynamic)	Fixed VLAN mode	Dynamic VLAN mode	Legacy mode	Fixed VLAN mode	Dynamic VLAN mode
Dead-interval functionality of RADIUS server communication	NG	NG	NG	OK	OK	NG	OK	OK