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Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-02
Chapter10 Configuring IEEE 802.1x Port-Based Authentication
Understanding IEEE 802.1x Port-Based Authentication
frame with a username and password based on the MAC address. If authorization succeeds, the switch
grants the client access to the network. If authorization fails, the switch assigns the port to the guest
VLAN if one is configured.
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 uses IEEE 802.1x
authentication (not MAC authentication bypass) to authorize the interface. EAPOL history is cleared if
the interface link status goes down.
If the switch already authorized a port by using MAC authentication bypass and detects an IEEE 802.1x
supplicant, the switch does not unauthorize the client connected to the port. When re-authentication
occurs, the switch uses IEEE 802.1x authentication as the preferred re-authentication process if the
previous session ended because the Termination-Action RADIUS attribute value is DEFAULT.
Clients that were authorized with MAC authentication bypass can be re-authenticated. The
re-authentication process is the same as that for clients that were authenticated with IEEE 802.1x.
During re-authentication, the port remains in the previously assigned VLAN. If re-authentication is
successful, the switch keeps the port in the same VLAN. If re-authentication fails, the switch assigns the
port to the guest VLAN, if one is configured.
If re-authentication is based on the Session-Timeout RADIUS attribute (Attribute[27]) and the
Termination-Action RADIUS attribute (Attribute [29]) and if the Termination-Action RADIUS attribute
(Attribute [29]) action is Initialize, (the attribute value is DEFAULT), the MAC authentication bypass
session ends, and connectivity is lost during re-authentication. If MAC authentication bypass is enabled
and the IEEE 802.1x authentication times out, the switch uses the MAC authentication bypass feature to
initiate re-authorization. For more information about these AV pairs, see RFC 3580, “IEEE 802.1X
Remote Authentication Dial In User Service (RADIUS) Usage Guidelines.”
MAC authentication bypass interacts with the features:
• IEEE 802.1x authentication—You can enable MAC authentication bypass only if IEEE 802.1x
authentication is enabled on the port.
• Guest VLAN—If a client has an invalid MAC address identity, the switch assigns the client to a
guest VLAN if one is configured.
• Restricted VLAN—This feature is not supported when the client connected to an IEEE 802.lx port
is authenticated with MAC authentication bypass.
• Port security—See the “Using IEEE 802.1x Authentication with Port Security” section on
page 10-16.
• Voice VLAN—See the “Using IEEE 802.1x Authentication with Voice VLAN Ports” section on
page 10-15.
• VLAN Membership Policy Server (VMPS)—IEEE802.1x and VMPS are mutually exclusive.
• Private VLAN—You can assign a client to a private VLAN.
• Network admission control (NAC) Layer 2 IP validation—This feature takes effect after an
IEEE 802.1x port is authenticated with MAC authentication bypass, including hosts in the exception
list.