Authentication Restart; 802.1X Interaction; Authentication Priority - Dell Networking N4000 Series Configuration Manual

When a client is connected to a port, the switch tries to authenticate the
user/client using the methods in configuration order. If any authentication
method times out (an error), then the next authentication method is tried. If
all authentication methods configured for the port error out, the switch starts
a timer whose value is equal to the authentication restart timer. At the expiry
of the timer, the switch restarts the authentication process from the first
method. This timer starts only when all of the authentication methods error
out.
The authentication manager controls only the order in which the
authentication methods are executed. The switch administrator is responsible
for implementing the required configuration for the respective methods to
authenticate successfully.

Authentication Restart

Authentication restarts from the first configured method on any of the
following events:
• Link flap
• Authentication fails for all configured methods
• Authentication priority (802.1X packet received when a lower priority
method is active)

802.1X Interaction

By default, 802.1X drops all traffic prior to successful 802.1X (or MAB)
authentication. If captive portal is configured as a method, authentication
allows certain traffic types, such as DHCP or DNS, access to the network
during the captive portal method invocation.

Authentication Priority

The default authentication priority of a method is equivalent to its position
in the order of the authentication list. If authentication method priorities are
not configured, then the relative priorities (first is highest) are in the same
order as that of the per-port based authentication list.
Configuring Port and System Security
579