DELL S50V User Manual

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802.1X | 121
Guest and Authentication-Fail VLANs
Typically, the authenticator (Dell Force10 system) denies the supplicant access to the network until the 
supplicant is authenticated. If the supplicant is authenticated, the authenticator enables the port and places 
it in either the VLAN for which the port is configured, or the VLAN that the authentication server indicates 
in the authentication data.
If the supplicant fails authentication, the authenticator typically does not enable the port. In some cases this 
behavior is not appropriate. External users of an enterprise network, for example, might not be able to be 
authenticated, but still need access to the network. Also, some dumb-terminals such as network printers do 
not have 802.1X capability and therefore cannot authenticate themselves. To be able to connect such 
devices, they must be allowed access the network without compromising network security.
The Guest VLAN 802.1X extension addresses this limitation with regard to non-802.1X capable devices, 
and the Authentication-fail VLAN 802.1X extension addresses this limitation with regard to external users.
If the supplicant fails authentication a specified number of times, the authenticator places the port in 
the Authentication-fail VLAN.
If a port is already forwarding on the Guest VLAN when 802.1X is enabled, then the port is moved out 
of the Guest VLAN, and the authentication process begins.
Configuring a Guest VLAN
If the supplicant does not respond to a Request Identity frame within a determined amount of time 
([
reauth-max
 + 1] * 
tx-period
) the system 
assumes that the host does not have 802.1X capability, and the port is placed in the Guest VLAN.
Configure a port to be placed in the Guest VLAN after failing to respond within the timeout period using 
the command 
dot1x guest-vlan
 from INTERFACE mode, as shown in 
.
Figure 7-12.  Configuring a Guest VLAN
View your configuration using the command 
show config
 from INTERFACE mode, as shown in 
show dot1x interface
 command from EXEC Privilege mode as shown 
.
Note: Ports cannot be dynamically assigned to the default VLAN.
FTOS(conf-if-gi-1/2)#dot1x guest-vlan 200
FTOS(conf-if-gi-1/2)#show config
!
interface GigabitEthernet 1/2
 switchport
 dot1x guest-vlan 200
 no shutdown
FTOS(conf-if-gi-1/2)#