802.1X Authentication Services Configuration Guide, Cisco IOS Release 15E
Configuring IEEE 802.1X Port-Based Authentication
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Configuring IEEE 802.1X Port-Based Authentication

Contents

Configuring IEEE 802.1X Port-Based Authentication

IEEE 802.1X port-based authentication is configured on a device to prevent unauthorized devices (supplicants) from gaining access to the network. The device can combine the function of a router, switch, and access point, depending on the fixed configuration or installed modules. The switch functions are provided by either built-in switch ports or a plug-in module with switch ports. This feature supports both access ports and trunk ports.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

Prerequisites for Configuring IEEE 802.1X Port-Based Authentication

The following tasks must be completed before implementing the IEEE 802.1X Port-Based Authentication feature:

  • IEEE 802.1X must be enabled on the device port.
  • The device must have a RADIUS configuration and be connected to the Cisco secure access control server (ACS). You should understand the concepts of the RADIUS protocol and have an understanding of how to create and apply access control lists (ACLs).
  • EAP support must be enabled on the RADIUS server.
  • You must configure the IEEE 802.1X supplicant to send an EAP-logoff (Stop) message to the switch when the user logs off. If you do not configure the IEEE 802.1X supplicant, an EAP-logoff message is not sent to the switch and the accompanying accounting Stop message is not sent to the authentication server. See the Microsoft Knowledge Base article at the location http:/​/​support.microsoft.com and set the SupplicantMode registry to 3 and the AuthMode registry to 1.
  • Authentication, authorization, and accounting (AAA) must be configured on the port for all network-related service requests. The authentication method list must be enabled and specified. A method list describes the sequence and authentication method to be queried to authenticate a user. See the IEEE 802.1X Authenticator feature module for information.
  • The port must be successfully authenticated.
The IEEE 802.1X Port-Based Authentication feature is available only on Cisco 89x and 88x series integrated switching routers (ISRs) that support switch ports.

Note


Optimal performance is obtained with a connection that has a maximum of eight hosts per port.


The following Cisco ISR-G2 routers are supported:

  • 1900
  • 2900
  • 3900
  • 3900e

The following cards or modules support switch ports:

  • Enhanced High-speed WAN interface cards (EHWICs) with ACL support:
    • EHWIC-4ESG-P
    • EHWIC-9ESG-P
    • EHWIC-4ESG
    • EHWIC-9ESG
  • High-speed WAN interface cards (HWICs) without ACL support:
    • HWIC-4ESW-P
    • HWIC-9ESW-P
    • HWIC-4ESW
    • HWIC-9ES

Note


Not all Cisco ISR routers support all the components listed. For information about module compatibility with a specific router platform, see Cisco EtherSwitch Modules Comparison.


To determine whether your router has switch ports that can be configured with the IEEE 802.1X Port-Based Authentication feature, use the show interfaces switchport command.

Restrictions for IEEE 802.1X Port-Based Authentication

IEEE 802.1X Port-Based Authentication Configuration Restrictions

  • The IEEE 802.1X Port-Based Authentication feature is available only on a switch port.
  • If the VLAN to which an IEEE 802.1X port is assigned is shut down, disabled, or removed, the port becomes unauthorized. For example, the port is unauthorized after the access VLAN to which a port is assigned shuts down or is removed.
  • When IEEE 802.1X authentication is enabled, ports are authenticated before any other Layer 2 or Layer 3 features are enabled.
  • Changes to a VLAN to which an IEEE 802.1X-enabled port is assigned are transparent and do not affect the switch port. For example, a change occurs if a port is assigned to a RADIUS server-assigned VLAN and is then assigned to a different VLAN after reauthentication.
  • When IEEE 802.1X authentication is enabled on a port, you cannot configure a port VLAN that is equal to a voice VLAN.
  • This feature does not support standard ACLs on the switch port.
  • The IEEE 802.1X protocol is supported only on Layer 2 static-access ports, Layer 2 static-trunk ports, voice VLAN-enabled ports, and Layer 3 routed ports.

    Note


    Ethernet interfaces can be configured either as access ports or as trunk ports with the following specifications:
    • An access port can have only one VLAN configured on the interface; it can carry traffic for only one VLAN.
    • A trunk port can have two or more VLANs configured on the interface; it can carry traffic for several VLANs simultaneously.

  • The IEEE 802.1X protocol is not supported on the following port types:
    • Dynamic-access ports—If you try to enable IEEE 802.1X authentication on a dynamic-access (VLAN Query Protocol [VQP]) port, an error message appears, and IEEE 802.1X authentication is not enabled. If you try to change an IEEE 802.1X-enabled port to dynamic VLAN assignment, an error message appears, and the VLAN configuration is not changed.
    • Dynamic ports—If you try to enable IEEE 802.1X authentication on a dynamic port, an error message appears, and IEEE 802.1X authentication is not enabled. If you try to change the mode of an IEEE 802.1X-enabled port to dynamic, an error message appears, and the port mode is not changed.
    • Switched Port Analyzer (SPAN) and Remote SPAN (RSPAN) destination ports—You can enable IEEE 802.1X authentication on a port that is a SPAN or RSPAN destination port. However, IEEE 802.1X authentication is disabled until the port is removed as a SPAN or RSPAN destination port. You can enable IEEE 802.1X authentication on a SPAN or RSPAN source port.

    Note


    A port in dynamic mode can negotiate with its neighbor to become a trunk port.


  • Configuring the same VLAN ID for both access and voice traffic (using the switchport access vlan vlan-id and the switchport voice vlan vlan-id commands) fails if authentication has already been configured on the port.
  • Configuring authentication on a port on which you have already configured switchport access vlan vlan-id and switchport voice vlan vlan-id fails if the access VLAN and voice VLAN have been configured with the same VLAN ID.

Upgrading from a Previous Software Release

In Cisco IOS Release 12.4(11)T, the implementation for IEEE 802.1X authentication changed from the previous releases. When IEEE 802.1X authentication is enabled, information about Port Fast is no longer added to the configuration.


Note


To ensure that information about any IEEE 802.1x-related commands that is entered on a port is automaticallly added to the running configuration to address any backward compatibility issues, use the dot1x pae authenticator command.

Information About IEEE 802.1X Port-Based Authentication

IEEE 802.1X Device Roles

With IEEE 802.1X authentication, the devices in the network have specific roles as shown in the figure below.

Figure 1. IEEE 802.1X Device Roles

  • Supplicant—Device (workstation) that requests access to the LAN and switch services and responds to requests from the router. The workstation must be running IEEE 802.1X-compliant client software such as that offered in the Microsoft Windows XP operating system. (The supplicant is sometimes called the client.)

    Note


    To resolve Windows XP network connectivity and IEEE 802.1X authentication issues, read the Microsoft Knowledge Base article at this URL: http:/​/​support.microsoft.com/​kb/​q303597/​.


  • Authentication server—Device that performs the actual authentication of the supplicant. The authentication server validates the identity of the supplicant and notifies the router whether or not the supplicant is authorized to access the LAN and switch services. The Network Access Device (or ISR router in this instance) transparently passes the authentication messages between the supplicant and the authentication server, and the authentication process is carried out between the supplicant and the authentication server. The particular EAP method used will be decided between the supplicant and the authentication server (RADIUS server). The RADIUS security system with EAP extensions is available in Cisco Secure Access Control Server Version 3.0 or later. RADIUS operates in a client and server model in which secure authentication information is exchanged between the RADIUS server and one or more RADIUS clients.
  • Authenticator (integrated services router (ISR) or wireless access point)—Router that controls the physical access to the network based on the authentication status of the supplicant. The router acts as an intermediary between the supplicant and the authentication server, requesting identity information from the supplicant, verifying that information with the authentication server, and relaying a response to the supplicant. The router includes the RADIUS client, which is responsible for encapsulating and decapsulating the EAP frames and interacting with the authentication server.

When the authenticator receives EAPOL frames and relays them to the authentication server, the EAPOL is stripped and the remaining EAP frame is reencapsulated in the RADIUS format. The EAP frames are not modified during encapsulation, and the authentication server must support EAP within the native frame format. When the authenticator receives frames from the authentication server, the server’s frame header is removed, leaving the EAP frame, which is then encapsulated for Ethernet and sent to the client.

IEEE 802.1X Authentication Initiation and Message Exchange

During IEEE 802.1X authentication, the router or the supplicant can initiate authentication. If you enable authentication on a port by using the authentication port-control auto interface configuration command, the router initiates authentication when the link state changes from down to up or periodically if the port remains up and unauthenticated. The router sends an EAP-request/identity frame to the supplicant to request its identity. Upon receipt of the frame, the supplicant responds with an EAP-response/identity frame.


Note


Effective with Cisco IOS Release 12.2(33)SXI, the authentication port-control command replaces the dot1xport-control command.


However, if during bootup the supplicant does not receive an EAP-request/identity frame from the router, the supplicant can initiate authentication by sending an EAPOL-start frame, which prompts the router to request the supplicant’s identity.


Note


If IEEE 802.1X authentication is not enabled or supported on the network access device, any EAPOL frames from the supplicant are dropped. If the supplicant does not receive an EAP-request/identity frame after three attempts to start authentication, the supplicant sends frames as if the port is in the authorized state. A port in the authorized state effectively means that the supplicant has been successfully authenticated. For more information, see the Ports in Authorized and Unauthorized States module.


When the supplicant supplies its identity, the router begins its role as the intermediary, passing EAP frames between the supplicant and the authentication server until authentication succeeds or fails. If the authentication succeeds, the router port becomes authorized. If the authentication fails, authentication can be retried, the port might be assigned to a VLAN that provides limited services, or network access is not granted. For more information, see the Ports in Authorized and Unauthorized States module.

The specific exchange of EAP frames depends on the authentication method being used. The figure below shows a message exchange initiated by the supplicant using the One-Time-Password (OTP) authentication method with a RADIUS server.

Figure 2. Message Exchange

IEEE 802.1X Authentication Process

To configure IEEE 802.1X port-based authentication, you must enable authentication, authorization, and accounting (AAA) and specify the authentication method list. A method list describes the sequence and authentication method to be queried to authenticate a user.

The AAA process begins with authentication. When IEEE 802.1X port-based authentication is enabled and the device attempting to authenticate is IEEE 802.1x-capable (meaning it supports the supplicant functionality), this event occurs:

  • If the supplicant identity is valid and the IEEE 802.1X authentication succeeds, the router grants the supplicant access to the network.

The router reauthenticates a supplicant when this situation occurs:

  • Periodic reauthentication is enabled, and the reauthentication timer expires.

You can configure the reauthentication timer to use a router-specific value or to be based on values from the RADIUS server.

After IEEE 802.1X authentication using a RADIUS server is configured, the router uses timers based on the Session-Timeout RADIUS attribute (Attribute [27]) and the Termination-Action RADIUS attribute (Attribute [29]).

The Session-Timeout RADIUS attribute (Attribute [27]) specifies the time after which reauthentication occurs.

The Termination-Action RADIUS attribute (Attribute [29]) specifies the action to take during reauthentication. The actions can be Initialize or ReAuthenticate. When the Initialize action is set (the attribute value is DEFAULT ), the IEEE 802.1x session ends, and connectivity is lost during reauthentication. When the ReAuthenticate action is set (the attribute value is RADIUS-Request), the session is not affected during reauthentication.

You manually reauthenticate the supplicant by entering the dot1x re-authenticate interface interface-name interface-number privileged EXEC command.

IEEE 802.1X Host Mode

You can configure an IEEE 802.1X port for single-host or for multihost mode. In single-host mode (see the figure IEEE 802.1X Device Roles in the Device Roles section of this module), only one supplicant can be authenticated by the IEEE 802.1X-enabled switch port. The router detects the supplicant by sending an EAPOL frame when the port link state changes to the up state. If a supplicant leaves or is replaced with another supplicant, the router changes the port link state to down, and the port returns to the unauthorized state.

In multihost mode, you can attach multiple hosts to a single IEEE 802.1X-enabled port. In this mode, only one of the attached supplicants must be authorized for all supplicants to be granted network access. If the port becomes unauthorized (reauthentication fails or an EAPOL-logoff message is received), the router denies network access to all of the attached supplicants.


Note


Cisco 870 series platforms do not support single-host mode.


IEEE 802.1X Port Authorization States

During IEEE 802.1X authentication, depending on the port state, the router can grant a supplicant access to the network. The port starts in the unauthorized state. While in this state, the port that is not configured as a voice VLAN port disallows all ingress traffic except for IEEE 802.1X authentication, Cisco Discovery Protocol (CDP), and STP packets. When a supplicant is successfully authenticated, the port changes to the authorized state, allowing all traffic for the supplicant to flow normally. If the port is configured as a voice VLAN port, the port allows VoIP traffic and IEEE 802.1X protocol packets before the supplicant is successfully authenticated.

If a client that does not support IEEE 802.1X authentication connects to an unauthorized IEEE 802.1X port, then the router requests the client’s identity. In this situation, if the client does not respond to the request, the port remains in the unauthorized state, and the client is not granted access to the network.

In contrast, when an IEEE 802.1X-enabled supplicant connects to a port that is not running the IEEE 802.1X standard, the supplicant initiates the authentication process by sending the EAPOL-start frame. When no response is received, the supplicant sends the request for a fixed number of times. Because no response is received, the supplicant begins sending frames as if the port is in the authorized state.

If the supplicant is successfully authenticated (receives an Accept frame from the authentication server), the port state changes to authorized, and all frames from the authenticated supplicant are allowed through the port. If the authentication fails, the port remains in the unauthorized state, but authentication can be retried. If the authentication server cannot be reached, the router can resend the request. If no response is received from the server after the specified number of attempts, authentication fails, and network access is not granted.

When a supplicant logs off, it sends an EAPOL-logoff message, causing the router port to change to the unauthorized state.

If the link state of a port changes from up to down, or if an EAPOL-logoff frame is received, the port returns to the unauthorized state.

IEEE 802.1X—Conditional Logging

Use the IEEE 802.1X—Conditional Logging feature for troubleshooting. When the Conditional Logging feature is enabled, the router generates debugging messages for packets entering or leaving the router on a specified interface; the router will not generate debugging output for packets entering or leaving through a different interface. You can specify the interfaces explicitly. For example, you may want to see only debugging messages for one interface or subinterface. You can also turn on debugging for all interfaces that meet the configured condition. This feature is useful on dial access servers, which have a large number of ports.

Normally, the router will generate debugging messages for every interface, resulting in a large number of messages. The large number of messages consumes system resources, and can affect your ability to find the specific information you need. By limiting the number of debugging messages, you can receive messages related to only the ports you want to troubleshoot.

For more information on conditional logging and enabling conditionally triggered debugging, see the “Enabling Conditionally Triggered Debugging” section of the “Troubleshooting and Fault Management” chapter in the Basic System Management Configuration Guide.

IEEE 802.1X MIB Support

Cisco IOS Release 12.4(11)T provides support for the following MIBs that provide SNMP access to IEEE 802.1X feature components:

  • IEEE8021-PAE-MIB
  • Cisco-PAE-MIB

The IEEE8021-PAE-MIB supports reporting of the following information:

  • The state of the IEEE 802.1X state machine on a particular port
  • Statistics associated with the state of the IEEE 802.1X state machine

The Cisco-PAE-MIB provides SNMP support for the logging and reporting of events, including:

  • Port mode
  • Guest VLAN number (details the Guest VLAN number configured on a port)
  • InGuestVLAN (indicates whether a port is in the Guest VLAN)

How to Configure IEEE 802.1X Port-Based Authentication

Enabling IEEE 802.1X Authentication and Authorization

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    aaa new-model

    4.    aaa authentication dot1x {default | listname} method1 [method2...]

    5.    dot1x system-auth-control

    6.    identity profile default

    7.    interface type slot/port

    8.    authentication port-control {auto | force-authorized | force-unauthorized}

    9.    dot1x pae [supplicant | authenticator | both]

    10.    end

    11.    show dot1x


DETAILED STEPS
     Command or ActionPurpose
    Step 1 enable


    Example:
    Device> enable
     

    Enables privileged EXEC mode.

    • Enter your password if prompted.
     
    Step 2 configure terminal


    Example:
    Device# configure terminal
     

    Enters global configuration mode.

     
    Step 3 aaa new-model


    Example:
    Device(config)# aaa new-model
     

    Enables AAA.

     
    Step 4 aaa authentication dot1x {default | listname} method1 [method2...]


    Example:
    Device(config)# aaa authentication dot1x default group radius
     

    Creates a series of authentication methods that are used to determine user privilege to access the privileged command level so that the device can communicate with the AAA server.

     
    Step 5 dot1x system-auth-control


    Example:
    Device(config)# dot1x system-auth-control
     

    Globally enables 802.1X port-based authentication.

     
    Step 6 identity profile default


    Example:
    Device(config)# identity profile default
     

    Creates an identity profile and enters dot1x profile configuration mode.

     
    Step 7 interface type slot/port


    Example:
    Device(config-identity-prof)# interface fastethernet 0/1
     

    Enters interface configuration mode and specifies the interface to be enabled for 802.1X authentication.

     
    Step 8 authentication port-control {auto | force-authorized | force-unauthorized}


    Example:
    Device(config-if)# authentication port-control auto
     

    Enables 802.1X port-based authentication on the interface.

    • auto—Enables IEEE 802.1X authentication and causes the port to begin in the unauthorized state, allowing only EAPOL frames to be sent and received through the port. The authentication process begins when the link state of the port changes from down to up or when an EAPOL-start frame is received. The router requests the identity of the supplicant and begins relaying authentication messages between the supplicant and the authentication server. Each supplicant attempting to access the network is uniquely identified by the router by using the supplicant MAC address.
    • force-authorized-—Disables IEEE 802.1X authentication and causes the port to change to the authorized state without any authentication exchange required. The port sends and receives normal traffic without IEEE 802.1X-based authentication of the client. This is the default setting.
    • force-unauthorized—Causes the port to remain in the unauthorized state, ignoring all attempts by the supplicant to authenticate. The router cannot provide authentication services to the supplicant through the port.
    Note   

    Effective with Cisco IOS Release 12.2(33)SXI, the authentication port-control command replaces the dot1xport-control command.

     
    Step 9 dot1x pae [supplicant | authenticator | both]


    Example:
    Device(config-if)# dot1x pae authenticator
     

    Sets the Port Access Entity (PAE) type.

    • supplicant—The interface acts only as a supplicant and does not respond to messages that are meant for an authenticator.
    • authenticator-—The interface acts only as an authenticator and does not respond to any messages meant for a supplicant.
    • both—The interface behaves both as a supplicant and as an authenticator and thus does respond to all dot1x messages.
     
    Step 10 end


    Example:
    Device(config-if)# end
     

    Exits interface configuration mode and enters privileged EXEC mode.

     
    Step 11 show dot1x


    Example:
    Device# show dot1x
     

    Displays whether 802.1X authentication has been configured on the device.

     

    Configuring the IEEE 802.1X Host Mode


    Note


    This section describes IEEE 802.1X security features available only on the switch ports.


    SUMMARY STEPS

      1.    enable

      2.    configure terminal

      3.    radius-server vsa send authentication

      4.    interface type number

      5.    authentication host-mode {multi-auth | multi-domain | multi-host | single-host} [open]

      6.    switchport voice vlan vlan-id

      7.    end

      8.    show authentication interface type number

      9.    copy running-config startup-config


    DETAILED STEPS
       Command or ActionPurpose
      Step 1 enable


      Example:
      Device> enable
       

      Enables privileged EXEC mode.

      • Enter your password if prompted.
       
      Step 2 configure terminal


      Example:
      Device# configure terminal
       

      Enters global configuration mode.

       
      Step 3 radius-server vsa send authentication


      Example:
      Device(config)# radius-server vsa send authentication
       

      Configures the Network Access Server (NAS) to recognize and use vendor-specific attributes.

       
      Step 4 interface type number


      Example:
      Device(config)# interface fastethernet 2/1
       

      Specifies the port to which multiple hosts are indirectly attached, and enters interface configuration mode.

       
      Step 5 authentication host-mode {multi-auth | multi-domain | multi-host | single-host} [open]


      Example:
      Device(config-if)# authentication host-mode single-host fastethernet 2/1
       

      Allows a single host (client) or multiple hosts on the 802.1X-authorized port.

      • The multi-auth keyword specifies multiple authentications to occur on the 802.1X-authorized port.
      • The multi-domain keyword specifies multi-domain authentication (MDA), which is used to enable authentication of both a host and a voice device, such as an IP phone (Cisco or non-Cisco) on the same switch port.
      • The multi-host keyword specifies multiple hosts on the 802.1X-authorized port.
      • The single-host keyword specifies a single client on the 802.1X-authorized port.
      • (Optional) The open keyword specifies that the port is open; that is, there are no access restrictions.

       
      Step 6 switchport voice vlan vlan-id


      Example:
      Device(config-if)# switchport voice vlan 2
       

      (Optional) Configures the voice VLAN.

       
      Step 7 end


      Example:
      Device(config-if)# end
       

      Exits interface configuration mode and returns to privileged EXEC mode.

       
      Step 8 show authentication interface type number


      Example:
      Device# show authentication interface
       

      Displays your entries.

       
      Step 9 copy running-config startup-config


      Example:
      Device# copy running-config startup-config
       

      Saves your entries in the configuration file.

       

      Enabling IEEE 802.1X SNMP Notifications on Switch Ports

      SUMMARY STEPS

        1.    enable

        2.    configure terminal

        3.    snmp-server enable traps dot1x notification-type


      DETAILED STEPS
         Command or ActionPurpose
        Step 1 enable


        Example:
        Router> enable
         

        Enables privileged EXEC mode.

        • Enter your password if prompted.
         
        Step 2 configure terminal


        Example:
        Router# configure terminal
         

        Enters global configuration mode.

         
        Step 3 snmp-server enable traps dot1x notification-type


        Example:
        Router(config)# snmp-server enable traps dot1x no-guest-vlan
         

        Enables SNMP logging and reporting when no Guest VLAN is configured or available.

         

        Configuration Examples for IEEE 802.1x Port-Based Authentication

        Example: Enabling IEEE 802.1X and AAA on a Port


        Note


        Effective with Cisco IOS Release 12.2(33)SXI, the authentication port-control command replaces the dot1xport-control command.



        Note


        Whenever you configure any IEEE 802.1X parameter on a port, a dot1x authenticator is automatically created on the port. As a result, the dot1x pae authenticator command appears in the configuration to ensure that IEEE 802.1X authentication still works without manual intervention on legacy configurations. The appearance of the IEEE 802.1X information in the configuration is likely to change in future releases.


        The following example shows how to enable IEEE 802.1X and AAA on Fast Ethernet port 2/1 and how to verify the configuration:

        Note


        In this example the Ethernet interface is configured as an access port by using the switchport mode access command in interface configuration mode. The Ethernet interface can also be configured as a trunk port using the switchport mode trunk command in interface configuration mode.


        Device> enable
        Device# configure terminal
        Device(config)# dot1x system-auth-control
        Device(config)# aaa new-model
        Device(config)# aaa authentication dot1x default group radius
        Device(config)# interface fastethernet2/1
        Device(config-if)# switchport mode access
        Device(config-if)# authentication port-control auto
        Device(config-if)# dot1x pae authenticator
        Device(config-if)# end
        
        Device# show dot1x interface fastethernet7/1 details
        
        Dot1x Info for FastEthernet7/1
        -----------------------------------
        PAE                       = AUTHENTICATOR
        PortControl               = AUTO
        ControlDirection          = Both 
        HostMode                  = SINGLE_HOST
        ReAuthentication          = Disabled
        QuietPeriod               = 60
        ServerTimeout             = 30
        SuppTimeout               = 30
        ReAuthPeriod              = 3600 (Locally configured)
        ReAuthMax                 = 2
        MaxReq                    = 2
        TxPeriod                  = 30
        RateLimitPeriod           = 0
        Dot1x Authenticator Client List
        -------------------------------
        Supplicant                = 1000.0000.2e00
                Auth SM State     = AUTHENTICATED
                Auth BEND SM Stat = IDLE
        Port Status               = AUTHORIZED
                  
        Authentication Method     = Dot1x
        Authorized By             = Authentication Server
        Vlan Policy               = N/A
        
        

        Example: Configuring the IEEE 802.1X Host Mode

        The following example shows how to enable 802.1X authentication and to allow multiple hosts:

        Device> enable
        Device# configure terminal
        Device(config)# interface gigabitethernet 2/0/1
        Device(config-if)# authentication port-control auto
        Device(config-if)# authentication host-mode multihost
        Device(config-if)# end
        

        Example: Displaying IEEE 802.1X Statistics and Status

        • To display IEEE 802.1X statistics for all ports, use the show dot1x all statistics command in privileged EXEC configuration mode.
        • To display IEEE 802.1X statistics for a specific port, use the show dot1x status interface type number command in privileged EXEC configuration mode.
        • To display the IEEE 802.1X administrative and operational status for the switch, use the show dot1x all [details | statistics | summary] command in privileged EXEC configuration mode.
        • To display the IEEE 802.1X administrative and operational status for a specific port, use the show dot1x interface type number command in privileged EXEC configuration mode. For detailed information about the fields in these displays, see the command reference for this release.

        The following example displays show dot1x all command output:

        Device# show dot1x all
        
        Sysauthcontrol                 Enabled
        Dot1x Protocol Version     2
        Dot1x Info for FastEthernet1
        -----------------------------------
        PAE                       = AUTHENTICATOR
        PortControl               = AUTO
        ControlDirection          = Both 
        HostMode                  = MULTI_HOST
        ReAuthentication          = Disabled
        QuietPeriod               = 60
        ServerTimeout             = 30
        SuppTimeout               = 30
        ReAuthPeriod              = 3600 (Locally configured)
        ReAuthMax                 = 2
        MaxReq                    = 2
        TxPeriod                  = 30
        RateLimitPeriod           = 0
        Router-871#
        

        The following example displays show dot1x summary command output:

        Device# show dot1x all summary
         
        Interface             PAE             Client                         Status 
        ------------------------------------------------------------------------------------------
        Fa1                   AUTH             000d.bcef.bfdc           AUTHORIZED
        

        Additional References for IEEE 802.1X Port-Based Authentication

        Standards and RFCs

        Standard/RFC Title

        IEEE 802.1X

        Port Based Network Access Control

        RFC 3580

        IEEE 802.1X Remote Authentication Dial In User Service (RADIUS) Usage Guidelines

        MIBs

        MIB

        MIBs Link

        • Cisco-PAE-MIB
        • IEEE8021-PAE-MIB

        To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

        http:/​/​www.cisco.com/​go/​mibs

        Technical Assistance

        Description

        Link

        The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

        http:/​/​www.cisco.com/​cisco/​web/​support/​index.html

        Feature Information for IEEE 802.1X Port-Based Authentication

        The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

        Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

        Table 1 Feature Information for IEEE 802.1X Port-Based Authentication

        Feature Name

        Releases

        Feature Information

        CDP Enhancement —Host Presence TLV

        Cisco IOS 15.2(1)E

        This features allows you to ensure that only one client can be connected to the 802.1X-enabled port. The switch detects the client by sending an EAPOL frame when the port link state changes to the up state. If a client leaves or is replaced with another client, the switch changes the port link state to down, and the port returns to the unauthorized state.

        In Cisco IOS XE 15.2(1)E, this feature was supported on the following platforms:
        • Catalyst 2960-C Series Switches
        • Catalyst 2960-S Series Switches
        • Catalyst 3560-C Series Switches
        • Catalyst 3560-X Series Switches
        • Catalyst 3750-X Series Switches
        • Catalyst 4500E Supervisor Engine 6-E
        • Catalyst 4500E Supervisor Engine 6L-E

        IEEE 802.1X Authenticator

        Cisco IOS 15.2(1)E

        This feature was introduced to prevent unauthorized devices (supplicants) from gaining access to the network.

        In Cisco IOS XE 15.2(1)E, this feature was supported on the following platforms:
        • Catalyst 2960-C Series Switches
        • Catalyst 2960-S Series Switches
        • Catalyst 3560-C Series Switches
        • Catalyst 3560-X Series Switches
        • Catalyst 3750-X Series Switches
        • Catalyst 4500E Supervisor Engine 6-E
        • Catalyst 4500E Supervisor Engine 6L-E

        The following commands were introduced or modified: aaa accounting, dot1x guest-vlan, snmp-server enable traps.

        IEEE 802.1X-Conditional Logging

        Cisco IOS 15.2(1)E

        The IEEE 802.1X-Conditional Logging feature is used for troubleshooting interfaces.

        In Cisco IOS XE 15.2(1)E, this feature was supported on the following platforms:
        • Catalyst 2960-C Series Switches
        • Catalyst 2960-S Series Switches
        • Catalyst 3560-C Series Switches
        • Catalyst 3560-X Series Switches
        • Catalyst 3750-X Series Switches
        • Catalyst 4500E Supervisor Engine 6-E
        • Catalyst 4500E Supervisor Engine 6L-E

        IEEE 802.1X MIB Support

        Cisco IOS 15.2(1)E

        This feature provides support for the following MIBs:

        • Cisco-PAE-MIB
        • IEEE8021-PAE-MIB
        In Cisco IOS XE 15.2(1)E, this feature was supported on the following platforms:
        • Catalyst 2960-C Series Switches
        • Catalyst 2960-S Series Switches
        • Catalyst 3560-C Series Switches
        • Catalyst 3560-X Series Switches
        • Catalyst 3750-X Series Switches
        • Catalyst 4500E Supervisor Engine 6-E
        • Catalyst 4500E Supervisor Engine 6L-E

        IEEE 802.1X Support for Trunk Ports

        Cisco IOS 15.2(1)E

        The IEEE 802.1X Support for Trunk Ports feature is used to configure Ethernet interfaces as trunk ports.

        In Cisco IOS XE 15.2(1)E, this feature was supported on the following platforms:
        • Catalyst 2960-C Series Switches
        • Catalyst 2960-S Series Switches
        • Catalyst 3560-C Series Switches
        • Catalyst 3560-X Series Switches
        • Catalyst 3750-X Series Switches
        • Catalyst 4500E Supervisor Engine 6-E
        • Catalyst 4500E Supervisor Engine 6L-E