10-23
Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-08
Chapter 10 Configuring IEEE 802.1x Port-Based Authentication
Understanding IEEE 802.1x Port-Based Authentication
re-authentication. If you do this, the only way to restart the authentication process is for the port to
receive a link down or EAP logoff event. We recommend that you keep re-authentication enabled if a
client might connect through a hub. When a client disconnects from the hub, the port might not receive
the link down or EAP logoff event.
After a port moves to the restricted VLAN, a simulated EAP success message is sent to the client. This
pr
events clients from indefinitely attempting authentication. Some clients (for example, devices running
Windows XP) cannot implement DHCP without EAP success.
Restricted VLANs are supported only on 802.1x ports in single-host mode and on Layer 2 ports.
You can configure any active VLAN except an RSPAN VLAN, a primary private VLAN, or a voice
V
LAN as an 802.1x restricted VLAN. The restricted VLAN feature is not supported on internal VLANs
(routed ports) or trunk ports; it is supported only on access ports.
This feature works with port security. As soon as the port is authorized, a MAC address is provided to
por
t security. If port security does not permit the MAC address or if the maximum secure address count
is reached, the port becomes unauthorized and error disabled.
Other port security features such as dynamic ARP Inspection, DHCP snooping, and IP source guard can
be
configured independently on a restricted VLAN.
For more information, see the “
Configuring a Restricted VLAN” section on page 10-52.
802.1x Authentication with Inaccessible Authentication Bypass
Use the inaccessible authentication bypass feature, also referred to as critical authentication or the AAA
fail policy, when the switch cannot reach the configured RADIUS servers and new hosts cannot be
authenticated. You can configure the switch to connect those hosts to critical ports.
When a new host tries to connect to the critical port, that host is moved to a user-specified access VLAN,
th
e critical VLAN. The administrator gives limited authentication to the hosts.
When the switch tries to authenticate a host connected to a critical port, the switch checks the status of
th
e configured RADIUS server. If a server is available, the switch can authenticate the host. However, if
all the RADIUS servers are unavailable, the switch grants network access to the host and puts the port
in the critical-authentication state, which is a special case of the authentication state.
Support on Multiple-Authentication Ports
To support inaccessible bypass on multiple-authentication (multiauth) ports, you can use the
authentication event server dead action reinitialize vlan vlan-id. When a new host tries to connect to
the critical port, that port is reinitialized and all the connected hosts are moved to the user-specified
access VLAN.
The au
thentication event server dead action reinitialize vlan vlan-id interface configuration
command is supported on all host modes.
Authentication Results
The behavior of the inaccessible authentication bypass feature depends on the authorization state of the
port:
• If the port is unauthorized when a host connected to a critical port tries to authenticate and all servers
are unavailable, the switch puts the port in the critical-authentication state in the
RADIUS-configured or user-specified access VLAN.
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