Vlan Id-Based Mac Authentication - Cisco 3032 Software Configuration Manual

Understanding IEEE 802.1x Port-Based Authentication

VLAN ID-based MAC Authentication

You can use VLAN ID-based MAC authentication if you wish to authenticate hosts based on a static
VLAN ID instead of a downloadable VLAN. When you have a static VLAN policy configured on your
switch, VLAN information is sent to an IAS (Microsoft) RADIUS server along with the MAC address
of each host for authentication. The VLAN ID configured on the connected port is used for MAC
authentication. By using VLAN ID-based MAC authentication with an IAS server, you can have a fixed
number of VLANs in the network.
The feature also limits the number of VLANs monitored and handled by STP.The network can be
managed as a fixed VLAN.
This feature is not supported on Cisco ACS Server. (The ACS server ignores the sent VLAN-IDs for new
Note
hosts and only authenticates based on the MAC address.)
For configuration information, see the
page
"Configuring MAC Authentication Bypass" section on page
802.1x Authentication with Guest VLAN
You can configure a guest VLAN for each 802.1x port on the switch to provide limited services to
clients, such as downloading the 802.1x client. These clients might be upgrading their system for 802.1x
authentication, and some hosts, such as Windows 98 systems, might not be IEEE 802.1x-capable.
When you enable a guest VLAN on an 802.1x port, the switch assigns clients to a guest VLAN when the
switch does not receive a response to its EAP request/identity frame or when EAPOL packets are not
sent by the client.
The switch maintains the EAPOL packet history. If an EAPOL packet is detected on the interface during
the lifetime of the link, the switch determines that the device connected to that interface is an
IEEE 802.1x-capable supplicant, and the interface does not change to the guest VLAN state. EAPOL
history is cleared if the interface link status goes down. If no EAPOL packet is detected on the interface,
the interface changes to the guest VLAN state.
If the switch is trying to authorize an 802.1x-capable voice device and the AAA server is unavailable,
the authorization attempt fails, but the detection of the EAPOL packet is saved in the EAPOL history.
When the AAA server becomes available, the switch authorizes the voice device. However, the switch
no longer allows other devices access to the guest VLAN. To prevent this situation, use one of these
command sequences:
•
•
Use a restricted VLAN to allow clients that failed authentication access to the network by entering the
dot1x auth-fail vlan vlan-id interface configuration command.
If devices send EAPOL packets to the switch during the lifetime of the link, the switch no longer allows
clients that fail authentication access to the guest VLAN.
Cisco Catalyst Blade Switch 3130 and 3032 for Dell Software Configuration Guide
9-20
9-62. Additional configuration is similar MAC authentication bypass, as described in the
Enter the dot1x guest-vlan supplicant global configuration command to allow access to the guest
VLAN.
Enter the shutdown interface configuration command followed by the no shutdown interface
configuration command to restart the port.
Chapter 9 Configuring IEEE 802.1x Port-Based Authentication
"Configuring VLAN ID-based MAC Authentication" section on
9-56.
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