Cisco IE-3000-8TC Software Configuration Guide - Page 252

Understanding IEEE 802.1x Port-Based Authentication Chapter 12 Configuring IEEE 802.1x Port-Based Authentication When you configure a port as unidirectional by using the authentication control-direction in or dot1x control-direction in interface configuration command, the port changes to the spanning-tree forwarding state. The port can send packets to the host but cannot receive packets from the host. When you configure a port as bidirectional by using the authentication control-direction both or dot1x control-direction both interface configuration command, the port is access-controlled in both directions. The port does not receive packets from or send packets to the host. 802.1x Authentication with MAC Authentication Bypass You can configure the switch to authorize clients based on the client MAC address (see Figure 12-2 on page 12-4) by using the MAC authentication bypass feature. For example, you can enable this feature on 802.1x ports connected to devices such as printers. If 802.1x authentication times out while waiting for an EAPOL response from the client, the switch tries to authorize the client by using MAC authentication bypass. When the MAC authentication bypass feature is enabled on an 802.1x port, the switch uses the MAC address as the client identity. The authentication server has a database of client MAC addresses that are allowed network access. After detecting a client on an 802.1x port, the switch waits for an Ethernet packet from the client. The switch sends the authentication server a RADIUS-access/request 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 802.1x-capable supplicant and uses 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 802.1x supplicant, the switch does not unauthorize the client connected to the port. When re-authentication occurs, the switch uses 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 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 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, "802.1X Remote Authentication Dial In User Service (RADIUS) Usage Guidelines." MAC authentication bypass interacts with the features: • 802.1x authentication-You can enable MAC authentication bypass only if 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. 12-22 Cisco IE 3000 Switch Software Configuration Guide OL-13018-03