If RADIUS server is not accessible (non-responsive), the host instantiation phase can be:
Terminated if there is no fallback action within authentication policy specified.
Continued within LUDB if the fallback action within the authentication-policy references LUDB.
Continued without any response from RADIUS. Subscriber-host is instantiated if defaults parameters are statically configured or the instantiation fails if the defaults are not available.
The fallback action takes effect after the preconfigured RADIUS timeout period expires.
RADIUS fallback is not supported for DHCPv6 hosts for non-IPoE sessions but is supported for IPoE sessions.