自己也遇到了这问题，挖坟
interface GigabitEthernet0/23
switchport mode access 这个一定开，不然没法用以下命令
authentication host-mode multi-auth 新版本功能多客户端认证，老版本如果交换机下面接了小交换机，其中一个客户端通过了，那小交换机的其他客户端就不需要认证，这个功能就是可以让所有小交换机上的客户端都需要认证。
authentication port-control auto 这个一定要开
dot1x pae authenticator 这个一定要开
spanning-tree portfast 这个无所谓，建议开，不然验证太慢
http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960/software/release/15-0_1_se/configuration/guide/scg2960/sw8021x.html#wp1430313
Step 1 configure terminal Enter global configuration mode.
Step 2 aaa new-model Enable AAA.
Step 3 aaa authentication dot1x {default}method1 Create an 802.1x authentication method list.To create a default list to use when a named list is not specified in the authenticationcommand, use the default keyword followed by the method to use in default situations. The default method list is automatically applied to all ports.For method1, enter the group radius keywords to use the list of all RADIUS servers for authentication.Note Though other keywords are visible in the command-line help string, only thegroup radius keywords are supported.
Step 4 dot1x system-auth-control Enable 802.1x authentication globally on the switch.
Step 5 aaa authorization network {default}group radius (Optional) Configure the switch to use user-RADIUS authorization for all network-related service requests, such as VLAN assignment.
Step 6 radius-server host ip-address (Optional) Specify the IP address of the RADIUS server.
Step 7 radius-server key string (Optional) Specify the authentication and encryption key used between the switch and the RADIUS daemon running on the RADIUS server.
Step 8 interfaceinterface-id Specify the port connected to the client to enable for 802.1x authentication, and enter interface configuration mode.
Step 9 switchport mode access (Optional) Set the port to access mode only if you configured the RADIUS server in Step 6 and Step 7.
Step 10 authentication port-control auto Enable 802.1x authentication on the port.For feature interaction information, see the "802.1x Authentication Configuration Guidelines" section.
Step 11 dot1x pae authenticator Set the interface Port Access Entity to act only as an authenticator and ignore messages meant for a supplicant.
Step 12 end Return to privileged EXEC mode.
Step 13 show authentication Verify your entries.
Step 14 copy running-config startup-config (Optional) Save your entries in the configuration file.
interface GigabitEthernet0/23
switchport mode access 这个一定开，不然没法用以下命令
authentication host-mode multi-auth 新版本功能多客户端认证，老版本如果交换机下面接了小交换机，其中一个客户端通过了，那小交换机的其他客户端就不需要认证，这个功能就是可以让所有小交换机上的客户端都需要认证。
authentication port-control auto 这个一定要开
dot1x pae authenticator 这个一定要开
spanning-tree portfast 这个无所谓，建议开，不然验证太慢
http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960/software/release/15-0_1_se/configuration/guide/scg2960/sw8021x.html#wp1430313
Step 1 configure terminal Enter global configuration mode.
Step 2 aaa new-model Enable AAA.
Step 3 aaa authentication dot1x {default}method1 Create an 802.1x authentication method list.To create a default list to use when a named list is not specified in the authenticationcommand, use the default keyword followed by the method to use in default situations. The default method list is automatically applied to all ports.For method1, enter the group radius keywords to use the list of all RADIUS servers for authentication.Note Though other keywords are visible in the command-line help string, only thegroup radius keywords are supported.
Step 4 dot1x system-auth-control Enable 802.1x authentication globally on the switch.
Step 5 aaa authorization network {default}group radius (Optional) Configure the switch to use user-RADIUS authorization for all network-related service requests, such as VLAN assignment.
Step 6 radius-server host ip-address (Optional) Specify the IP address of the RADIUS server.
Step 7 radius-server key string (Optional) Specify the authentication and encryption key used between the switch and the RADIUS daemon running on the RADIUS server.
Step 8 interfaceinterface-id Specify the port connected to the client to enable for 802.1x authentication, and enter interface configuration mode.
Step 9 switchport mode access (Optional) Set the port to access mode only if you configured the RADIUS server in Step 6 and Step 7.
Step 10 authentication port-control auto Enable 802.1x authentication on the port.For feature interaction information, see the "802.1x Authentication Configuration Guidelines" section.
Step 11 dot1x pae authenticator Set the interface Port Access Entity to act only as an authenticator and ignore messages meant for a supplicant.
Step 12 end Return to privileged EXEC mode.
Step 13 show authentication Verify your entries.
Step 14 copy running-config startup-config (Optional) Save your entries in the configuration file.
