Configuring IEEE 802.1x Port-Based Authentication

This chapter describes how to configure IEEE 802.1x port-based authentication. IEEE 802.1x authentication prevents unauthorized devices (clients) from gaining access to the network. Unless otherwise noted, the term switch refers to a standalone switch or a switch stack.

Restrictions for IEEE 802.1x Port-Based Authentication

  • Switchports are always unauthorized when used with private VLANs. Dynamic VLANs pushed from the Authentication, Authorization, and Accounting (AAA) server is not supported on private VLAN ports. The data client session is expected to authorize on the secondary VLAN of the private VLAN dot1x port.

  • Only interface-configured private VLAN-based authorization and dynamic VLAN on a normal access VLAN port is supported.

  • If the dot1q tag vlan native command is configured globally, the dot1x reauthentication will fail on trunk ports.

  • Do not configure the same VLAN ID for both voice VLAN and access VLAN at the same time, because it may cause authentication failures.

  • If a downloadable ACL contains any type of duplicate entries, the entries are not auto merged. As a result, the 802.1X session authorization fails. Ensure that the downloadable ACL is optimized without any duplicate entries, for example port-based and name-based entries for the same port.

  • Port security is not supported with IEEE 802.1x port-based authentication.

  • If you overwrite the running configuration of interfaces with a configuration file loaded in flash, some ports may fail to authenticate the endpoints.

  • Wake-on-LAN (WoL) feature is not supported.

Information About IEEE 802.1x Port-Based Authentication

The 802.1x standard defines a client-server-based access control and authentication protocol that prevents unauthorized clients from connecting to a LAN through publicly accessible ports unless they are properly authenticated. The authentication server authenticates each client connected to a switch port before making available any services offered by the switch or the LAN.


Note
TACACS is not supported with 802.1x authentication.

Until the client is authenticated, 802.1x access control allows only Extensible Authentication Protocol over LAN (EAPOL), Cisco Discovery Protocol, and Spanning Tree Protocol (STP) traffic through the port to which the client is connected. After authentication is successful, normal traffic can pass through the port.

The table shown below lists the maximum number of session each client supports:

Client session

Maximum sessions supported

Maximum dot1x or MAB client sessions

2000

Maximum web-based authentication sessions

2000

Maximum dot1x sessions with critical-auth VLAN enabled and server re-initialized

2000

Maximum MAB sessions with various session features applied

2000

Maximum dot1x sessions with service templates or session features applied

2000

Overview of IEEE 802.1x Port-Based Authentication

The 802.1x standard defines a client-server-based access control and authentication protocol that prevents unauthorized clients from connecting to a LAN through publicly accessible ports unless they are properly authenticated. The authentication server authenticates each client connected to a switch port before making available any services offered by the switch or the LAN.


Note
TACACS is not supported with 802.1x authentication.

Until the client is authenticated, 802.1x access control allows only Extensible Authentication Protocol over LAN (EAPOL), Cisco Discovery Protocol, and Spanning Tree Protocol (STP) traffic through the port to which the client is connected. After authentication is successful, normal traffic can pass through the port.

Port-Based 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 802.1x port-based authentication is enabled and the client supports 802.1x-compliant client software, these events occur:

  • If the client identity is valid and the 802.1x authentication succeeds, the switch grants the client access to the network.

  • If 802.1x authentication times out while waiting for an EAPOL message exchange and MAC authentication bypass is enabled, the switch can use the client MAC address for authorization. If the client MAC address is valid and the authorization succeeds, the switch grants the client access to the network. If the client MAC address is invalid and the authorization fails, the switch assigns the client to a guest VLAN that provides limited services if a guest VLAN is configured.

  • If the switch gets an invalid identity from an 802.1x-capable client and a restricted VLAN is specified, the switch can assign the client to a restricted VLAN that provides limited services.

  • If the RADIUS authentication server is unavailable (down) and inaccessible authentication bypass is enabled, the switch grants the client access to the network by putting the port in the critical-authentication state in the RADIUS-configured or the user-specified access VLAN.


    Note

    Inaccessible authentication bypass is also referred to as critical authentication or the AAA fail policy.

If Multi Domain Authentication (MDA) is enabled on a port, this flow can be used with some exceptions that are applicable to voice authorization.

Figure 1. Authentication Flowchart. This figure shows the authentication process.

The switch re-authenticates a client when one of these situations occurs:

  • Periodic re-authentication is enabled, and the re-authentication timer expires.

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

    After 802.1x authentication using a RADIUS server is configured, the switch 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 re-authentication occurs. The range is 1 to 65535 seconds.

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

  • You manually re-authenticate the client by entering the dot1x re-authenticate interface interface-id privileged EXEC command.

Port-Based Authentication Initiation and Message Exchange

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

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


Note

If 802.1x authentication is not enabled or supported on the network access device, any EAPOL frames from the client are dropped. If the client does not receive an EAP-request/identity frame after three attempts to start authentication, the client sends frames as if the port is in the authorized state. A port in the authorized state effectively means that the client has been successfully authenticated.

When the client supplies its identity, the switch begins its role as the intermediary, passing EAP frames between the client and the authentication server until authentication succeeds or fails. If the authentication succeeds, the switch 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.

The specific exchange of EAP frames depends on the authentication method being used.

Figure 2. Message Exchange. This figure shows a message exchange initiated by the client when the client uses the One-Time-Password (OTP) authentication method with a RADIUS server.

If 802.1x authentication times out while waiting for an EAPOL message exchange and MAC authentication bypass is enabled, the switch can authorize the client when the switch detects an Ethernet packet from the client. The switch uses the MAC address of the client as its identity and includes this information in the RADIUS-access/request frame that is sent to the RADIUS server. After the server sends the switch the RADIUS-access/accept frame (authorization is successful), the port becomes authorized. If authorization fails and a guest VLAN is specified, the switch assigns the port to the guest VLAN. If the switch detects an EAPOL packet while waiting for an Ethernet packet, the switch stops the MAC authentication bypass process and starts 802.1x authentication.

Figure 3. Message Exchange During MAC Authentication Bypass. This figure shows the message exchange during MAC authentication bypass.

Port-Based Authentication Methods

Table 1. 802.1x Features

Authentication method

Mode

Single host

Multiple host

MDA

Multiple Authentication

802.1x

VLAN assignment

Per-user ACL

Filter-ID attribute

Downloadable ACL

Redirect URL

VLAN assignment

VLAN assignment

Per-user ACL

Filter-Id attribute

Downloadable ACL

Redirect URL

VLAN assignment

Per-user ACL

Filter-Id attribute

Downloadable ACL

Redirect URL

MAC authentication bypass

VLAN assignment

Per-user ACL

Filter-ID attribute

Downloadable ACL

Redirect URL

VLAN assignment

VLAN assignment

Per-user ACL

Filter-Id attribute

Downloadable ACL

Redirect URL

VLAN assignment

Per-user ACL

Filter-Id attribute

Downloadable ACL

Redirect URL

Standalone web authentication

Proxy ACL, Filter-Id attribute, downloadable ACL

NAC Layer 2 IP validation

Filter-Id attribute

Downloadable ACL

Redirect URL

Filter-Id attribute

Downloadable ACL

Redirect URL

Filter-Id attribute

Downloadable ACL

Redirect URL

Filter-Id attribute

Downloadable ACL

Redirect URL

Web authentication as fallback method

Proxy ACL

Filter-Id attribute

Downloadable ACL

Proxy ACL

Filter-Id attribute

Downloadable ACL

Proxy ACL

Filter-Id attribute

Downloadable ACL

Proxy ACL

Filter-Id attribute

Downloadable ACL

1 Supported in Cisco IOS Release 12.2(50)SE and later.
2 For clients that do not support 802.1x authentication.

Per-User ACLs and Filter IDs


Note

Using role-based ACLs as Filter ID is not recommended.

More than one host can be authenticated on MDA-enabled and multiauth ports. The ACL policy applied for one host does not effect the traffic of another host. If only one host is authenticated on a multi-host port, and the other hosts gain network access without authentication, the ACL policy for the first host can be applied to the other connected hosts by specifying any in the source address.

Ports in Authorized and Unauthorized States

During 802.1x authentication, depending on the switch port state, the switch can grant a client 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 and egress traffic except for 802.1x authentication, Cisco Discovery Protocol, and STP packets. When a client is successfully authenticated, the port changes to the authorized state, allowing all traffic for the client to flow normally. If the port is configured as a voice VLAN port, the port allows VoIP traffic and 802.1x protocol packets before the client is successfully authenticated.


Note
Cisco Discovery Protocol bypass is not supported and may cause a port to go into err-disabled state.

If a client that does not support 802.1x authentication connects to an unauthorized 802.1x port, the switch requests the client’s identity. In this situation, 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 802.1x-enabled client connects to a port that is not running the 802.1x standard, the client initiates the authentication process by sending the EAPOL-start frame. When no response is received, the client sends the request for a fixed number of times. Because no response is received, the client begins sending frames as if the port is in the authorized state.

You control the port authorization state by using the authentication port-control interface configuration command and these keywords:

  • force-authorized : Disables 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 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 client to authenticate. The switch cannot provide authentication services to the client through the port.

  • auto : Enables 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 switch requests the identity of the client and begins relaying authentication messages between the client and the authentication server. Each client attempting to access the network is uniquely identified by the switch by using the client MAC address.

If the client is successfully authenticated (receives an Accept frame from the authentication server), the port state changes to authorized, and all frames from the authenticated client 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 switch 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 client logs off, it sends an EAPOL-logoff message, causing the switch 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.

802.1x Host Mode

You can configure an 802.1x port for single-host or for multiple-hosts mode. In single-host mode, only one client can be connected to the 802.1x-enabled switch 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 multiple-hosts mode, you can attach multiple hosts to a single 802.1x-enabled port. In this mode, only one of the attached clients must be authorized for all clients to be granted network access. If the port becomes unauthorized (reauthentication fails or an EAPOL-logoff message is received), the switch denies network access to all of the attached clients.

In this topology, the wireless access point is responsible for authenticating the clients attached to it, and it also acts as a client to the switch.

Figure 4. Multiple Host Mode Example



Note
For all host modes, the line protocol stays up before authorization when port-based authentication is configured.

The switch supports multidomain authentication (MDA), which allows both a data device and a voice device, such as an IP Phone, to connect to the same switch port.

Access Session Limit Profile

An access session limit profile will allow you to limit the number of voice and data hosts connecting to a port. An access session limit profile will have higher priority compared to any host mode configuration. When an access session limit profile is configured the host mode configuration will be ignored.

You can create an access session limit profile by using the access-session limit profile command in the global configuration mode. You can configure the profile to limit the number of data and voice sessions allowed per interface. The profile can be configured to allow multiple hosts and to bypass authentication based on CDP packets if CDP bypass is supported.

The access session limit profile needs to be applied at an interface level.

You can also attach the access session limit profile to an interface template.

MAC Move

When a MAC address is authenticated on one switch port, that address is not allowed on another authentication manager-enabled port of the switch. If the switch detects that same MAC address on another authentication manager-enabled port, the address is not allowed.

There are situations where a MAC address might need to move from one port to another on the same switch. For example, when there is another device (for example a hub or an IP phone) between an authenticated host and a switch port, you might want to disconnect the host from the device and connect it directly to another port on the same switch.

You can globally enable MAC move so the device is reauthenticated on the new port. When a host moves to a second port, the session on the first port is deleted, and the host is reauthenticated on the new port. MAC move is supported on all host modes. (The authenticated host can move to any port on the switch, no matter which host mode is enabled on that port.) When a MAC address moves from one port to another, the switch terminates the authenticated session on the original port and initiates a new authentication sequence on the new port. The MAC move feature applies to both voice and data hosts.


Note

In open authentication mode, a MAC address is immediately moved from the original port to the new port, with no requirement for authorization on the new port.

MAC Replace

The MAC Replace feature can be configured to address the violation that occurs when a host attempts to connect to a port where another host was previously authenticated.


Note

This feature does not apply to ports in multi-auth mode, because violations are not triggered in that mode. It does not apply to ports in multiple host mode, because in that mode, only the first host requires authentication.

If you configure the authentication violation interface configuration command with the replace keyword, the authentication process on a port in multidomain mode is:

  • A new MAC address is received on a port with an existing authenticated MAC address.

  • The authentication manager replaces the MAC address of the current data host on the port with the new MAC address.

  • The authentication manager initiates the authentication process for the new MAC address.

  • If the authentication manager determines that the new host is a voice host, the original voice host is removed.

If a port is in open authentication mode, any new MAC address is immediately added to the MAC address table.

802.1x Accounting

The 802.1x standard defines how users are authorized and authenticated for network access but does not keep track of network usage. 802.1x accounting is disabled by default. You can enable 802.1x accounting to monitor this activity on 802.1x-enabled ports:

  • User successfully authenticates.

  • User logs off.

  • Link-down occurs.

  • Reauthentication successfully occurs.

  • Reauthentication fails.

The switch does not log 802.1x accounting information. Instead, it sends this information to the RADIUS server, which must be configured to log accounting messages.

802.1x Accounting Attribute-Value Pairs

The information sent to the RADIUS server is represented in the form of Attribute-Value (AV) pairs. These AV pairs provide data for different applications. (For example, a billing application might require information that is in the Acct-Input-Octets or the Acct-Output-Octets attributes of a RADIUS packet.)

AV pairs are automatically sent by a switch that is configured for 802.1x accounting. Three types of RADIUS accounting packets are sent by a switch:

  • START–sent when a new user session starts

  • INTERIM–sent during an existing session for updates

  • STOP–sent when a session terminates

This table lists the AV pairs and when they are sent are sent by the switch.

Table 2. Accounting AV Pairs

Attribute Number

AV Pair Name

START

INTERIM

STOP

Attribute[1]

User-Name

Always

Always

Always

Attribute[4]

NAS-IP-Address

Always

Always

Always

Attribute[5]

NAS-Port

Always

Always

Always

Attribute[8]

Framed-IP-Address

Never

Sometimes3

Sometimes

Attribute[30]

Called-Station-ID

Always

Always

Always

Attribute[31]

Calling-Station-ID

Always

Always

Always

Attribute[40]

Acct-Status-Type

Always

Always

Always

Attribute[41]

Acct-Delay-Time

Always

Always

Always

Attribute[42]

Acct-Input-Octets

Never

Always

Always

Attribute[43]

Acct-Output-Octets

Never

Always

Always

Attribute[47]

Acct-Input-Packets

Never

Always

Always

Attribute[48]

Acct-Output-Packets

Never

Always

Always

Attribute[44]

Acct-Session-ID

Always

Always

Always

Attribute[45]

Acct-Authentic

Always

Always

Always

Attribute[46]

Acct-Session-Time

Never

Always

Always

Attribute[49]

Acct-Terminate-Cause

Never

Never

Always

Attribute[61]

NAS-Port-Type

Always

Always

Always

3 The Framed-IP-Address AV pair is sent when a valid static IP address is configured or w when a Dynamic Host Control Protocol (DHCP) binding exists for the host in the DHCP snooping bindings table.

802.1x Readiness Check

The 802.1x readiness check monitors 802.1x activity on all the switch ports and displays information about the devices connected to the ports that support 802.1x. You can use this feature to determine if the devices connected to the switch ports are 802.1x-capable. You use an alternate authentication such as MAC authentication bypass or web authentication for the devices that do not support 802.1x functionality.

This feature only works if the supplicant on the client supports a query with the NOTIFY EAP notification packet. The client must respond within the 802.1x timeout value.

Switch-to-RADIUS Server Communication

RADIUS security servers are identified by their hostname or IP address, hostname and specific UDP port numbers, or IP address and specific UDP port numbers. The combination of the IP address and UDP port number creates a unique identifier, which enables RADIUS requests to be sent to multiple UDP ports on a server at the same IP address. If two different host entries on the same RADIUS server are configured for the same service, for example, authentication, the second host entry configured acts as the fail-over backup to the first one. The RADIUS host entries are tried in the order that they were configured.

IEEE 802.1x Authentication

802.1x Authentication

These are the 802.1x authentication configuration guidelines:

  • You must enable SISF-Based device tracking to use 802.1x authentication. By default, SISF-Based device tracking is disabled on a switch.

  • When 802.1x authentication is enabled, ports are authenticated before any other Layer 2 or Layer 3 features are enabled.

  • If the VLAN to which an 802.1x-enabled port is assigned changes, this change is transparent and does not affect the switch. For example, this change occurs if a port is assigned to a RADIUS server-assigned VLAN and is then assigned to a different VLAN after re-authentication.

    If the VLAN to which an 802.1x port is assigned to 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.

  • The 802.1x protocol is supported on Layer 2 static-access ports, voice VLAN ports, and Layer 3 routed ports, but it is not supported on these port types:

    • Dynamic ports—A port in dynamic mode can negotiate with its neighbor to become a trunk port. If you try to enable 802.1x authentication on a dynamic port, an error message appears, and 802.1x authentication is not enabled. If you try to change the mode of an 802.1x-enabled port to dynamic, an error message appears, and the port mode is not changed.

    • EtherChannel port—Do not configure a port that is an active or a not-yet-active member of an EtherChannel as an 802.1x port. If you try to enable 802.1x authentication on an EtherChannel port, an error message appears, and 802.1x authentication is not enabled.

    • Switched Port Analyzer (SPAN) and Remote SPAN (RSPAN) destination ports—You can enable 802.1x authentication on a port that is a SPAN or RSPAN destination port. However, 802.1x authentication is disabled until the port is removed as a SPAN or RSPAN destination port. You can enable 802.1x authentication on a SPAN or RSPAN source port.

  • Before globally enabling 802.1x authentication on a switch by entering the dot1x system-auth-control global configuration command, remove the EtherChannel configuration from the interfaces on which 802.1x authentication and EtherChannel are configured.

  • Filtering of system messages related to 802.1x authentication is supported.


Note

We recommend that you configure all the dependent 802.1x CLIs under the same interface or on the same template.

Port-Based Authentication Manager CLI Commands

The authentication-manager interface-configuration commands control all the authentication methods, such as 802.1x, MAC authentication bypass, and web authentication. The authentication manager commands determine the priority and order of authentication methods applied to a connected host.

The authentication manager commands control generic authentication features, such as host-mode, violation mode, and the authentication timer. Generic authentication commands include the authentication host-mode , authentication violation , and authentication timer interface configuration commands.

802.1x-specific commands begin with the dot1x keyword. For example, the authentication port-control auto interface configuration command enables authentication on an interface.

To disable dot1x on a switch, remove the configuration globally by using the no dot1x system-auth-control , and also remove it from all configured interfaces.


Note

If 802.1x authentication is globally disabled, other authentication methods are still enabled on that port, such as web authentication.

The authentication manager commands provide the same functionality as earlier 802.1x commands.

When filtering out verbose system messages generated by the authentication manager, the filtered content typically relates to authentication success. You can also filter verbose messages for 802.1x authentication and MAB authentication. There is a separate command for each authentication method:

  • The no authentication logging verbose global configuration command filters verbose messages from the authentication manager.

  • The no dot1x logging verbose global configuration command filters 802.1x authentication verbose messages.

  • The no mab logging verbose global configuration command filters MAC authentication bypass (MAB) verbose messages

Default 802.1x Authentication Configuration

Table 3. Default 802.1x Authentication Configuration

Feature

Default Setting

Switch 802.1x enable state

Disabled.

Per-port 802.1x enable state

Disabled (force-authorized).

The port sends and receives normal traffic without 802.1x-based authentication of the client.

AAA

Disabled.

RADIUS server

  • IP address

  • UDP authentication port

  • Default accounting port

  • Key

  • None specified.

  • 1645.

  • 1646.

  • None specified.

Host mode

Single-host mode.

Control direction

Bidirectional control.

Periodic re-authentication

Disabled.

Number of seconds between re-authentication attempts

3600 seconds.

Re-authentication number

2 times (number of times that the switch restarts the authentication process before the port changes to the unauthorized state).

Quiet period

60 seconds (number of seconds that the switch remains in the quiet state following a failed authentication exchange with the client).

Retransmission time

30 seconds (number of seconds that the switch should wait for a response to an EAP request/identity frame from the client before resending the request).

Maximum retransmission number

2 times (number of times that the switch will send an EAP-request/identity frame before restarting the authentication process).

Client timeout period

30 seconds (when relaying a request from the authentication server to the client, the amount of time the switch waits for a response before resending the request to the client.)

Authentication server timeout period

30 seconds (when relaying a response from the client to the authentication server, the amount of time the switch waits for a reply before resending the response to the server.)

You can change this timeout period by using the dot1x timeout server-timeout interface configuration command.

Inactivity timeout

Disabled.

Guest VLAN

None specified.

Inaccessible authentication bypass

Disabled.

Restricted VLAN

None specified.

Authenticator (switch) mode

None specified.

MAC authentication bypass

Disabled.

Voice-aware security

Disabled.

Port-Based Authentication and Switch Stacks

If a switch is added to or removed from a switch stack, 802.1x authentication is not affected as long as the IP connectivity between the RADIUS server and the stack remains intact. This statement also applies if the stack's active switch is removed from the switch stack. Note that if the active switch fails, a member switch in the stack becomes the new active switch by using the election process, and the 802.1x authentication process continues as usual.

If IP connectivity to the RADIUS server is interrupted because the switch that was connected to the server is removed or fails, these events occur:

  • Ports that are already authenticated and that do not have periodic reauthentication enabled remain in the authenticated state. Communication with the RADIUS server is not required.

  • Ports that are already authenticated and that have periodic reauthentication enabled (with the dot1x re-authentication global configuration command) fail the authentication process when the reauthentication occurs. Ports return to the unauthenticated state during the reauthentication process. Communication with the RADIUS server is required.

    For an ongoing authentication, the authentication fails immediately because there is no server connectivity.

If the switch that failed comes up and rejoins the switch stack, the authentications might or might not fail depending on the boot-up time and whether the connectivity to the RADIUS server is re-established by the time the authentication is attempted.

To avoid loss of connectivity to the RADIUS server, you should ensure that there is a redundant connection to it. For example, you can have a redundant connection to the active switch and another to a member switch, and if the active switch fails, the switch stack still has connectivity to the RADIUS server.

802.1x Authentication with VLAN Assignment

The switch supports 802.1x authentication with VLAN assignment. After successful 802.1x authentication of a port, the RADIUS server sends the VLAN assignment to configure the switch port. The RADIUS server database maintains the username-to-VLAN mappings, assigning the VLAN based on the username of the client connected to the switch port. You can use this feature to limit network access for certain users.

When a voice device is authorized and the RADIUS server returned an authorized VLAN, the voice VLAN on the port is configured to send and receive packets on the assigned voice VLAN. Voice VLAN assignment behaves the same as data VLAN assignment on multidomain authentication (MDA)-enabled ports.

When configured on the switch and the RADIUS server, 802.1x authentication with VLAN assignment has these characteristics:

  • If no VLAN is supplied by the RADIUS server or if 802.1x authentication is disabled, the port is configured in its access VLAN after successful authentication. Recall that an access VLAN is a VLAN assigned to an access port. All packets sent from or received on this port belong to this VLAN.

  • If 802.1x authentication is enabled but the VLAN information from the RADIUS server is not valid, authorization fails and configured VLAN remains in use. This prevents ports from appearing unexpectedly in an inappropriate VLAN because of a configuration error.

    Configuration errors could include specifying a VLAN for a routed port, a malformed VLAN ID, a nonexistent or internal (routed port) VLAN ID, an RSPAN VLAN, a shut down or suspended VLAN. In the case of a multidomain host port, configuration errors can also be due to an attempted assignment of a data VLAN that matches the configured or assigned voice VLAN ID (or the reverse).

  • If 802.1x authentication is enabled and all information from the RADIUS server is valid, the authorized device is placed in the specified VLAN after authentication.

  • If the multiple-hosts mode is enabled on an 802.1x port, all hosts are placed in the same VLAN (specified by the RADIUS server) as the first authenticated host.

  • Enabling port security does not impact the RADIUS server-assigned VLAN behavior.

  • If 802.1x authentication is disabled on the port, it is returned to the configured access VLAN and configured voice VLAN.

  • If an 802.1x port is authenticated and put in the RADIUS server-assigned VLAN, any change to the port access VLAN configuration does not take effect. In the case of a multidomain host, the same applies to voice devices when the port is fully authorized with these exceptions:

    • If the VLAN configuration change of one device results in matching the other device configured or assigned VLAN, then authorization of all devices on the port is terminated and multidomain host mode is disabled until a valid configuration is restored where data and voice device configured VLANs no longer match.

    • If a voice device is authorized and is using a downloaded voice VLAN, the removal of the voice VLAN configuration, or modifying the configuration value to dot1p or untagged results in voice device unauthorization and the disablement of multi-domain host mode.

When the port is in the force authorized, force unauthorized, unauthorized, or shutdown state, it is put into the configured access VLAN.

To configure VLAN assignment you need to perform these tasks:

  • Enable AAA authorization by using the network keyword to allow interface configuration from the RADIUS server.

  • Enable 802.1x authentication. (The VLAN assignment feature is automatically enabled when you configure 802.1x authentication on an access port).

  • Assign vendor-specific tunnel attributes in the RADIUS server. The RADIUS server must return these attributes to the switch:

    • [64] Tunnel-Type = VLAN

    • [65] Tunnel-Medium-Type = 802

    • [81] Tunnel-Private-Group-ID = VLAN name or VLAN ID

    • [83] Tunnel-Preference

    Attribute [64] must contain the value VLAN (type 13). Attribute [65] must contain the value 802 (type 6). Attribute [81] specifies the VLAN name or VLAN ID assigned to the IEEE 802.1x-authenticated user.

802.1x Authentication with Per-User ACLs

You can enable per-user access control lists (ACLs) to provide different levels of network access and service to an 802.1x-authenticated user. When the RADIUS server authenticates a user connected to an 802.1x port, it retrieves the ACL attributes based on the user identity and sends them to the switch. The switch applies the attributes to the 802.1x port for the duration of the user session. The switch removes the per-user ACL configuration when the session is over, if authentication fails, or if a link-down condition occurs. The switch does not save RADIUS-specified ACLs in the running configuration. When the port is unauthorized, the switch removes the ACL from the port.

You can configure router ACLs and input port ACLs on the same switch. However, a port ACL takes precedence over a router ACL. If you apply input port ACL to an interface that belongs to a VLAN, the port ACL takes precedence over an input router ACL applied to the VLAN interface. Incoming packets received on the port, to which a port ACL is applied, are filtered by the port ACL. Incoming routed packets received on other ports are filtered by the router ACL. Outgoing routed packets are filtered by the router ACL. To avoid configuration conflicts, you should carefully plan the user profiles stored on the RADIUS server.

RADIUS supports per-user attributes, including vendor-specific attributes. These vendor-specific attributes (VSAs) are in octet-string format and are passed to the switch during the authentication process. The VSAs used for per-user ACLs are inacl#<n> for the ingress direction and outacl#<n> for the egress direction. MAC ACLs are supported only in the ingress direction. The switch supports VSAs only in the ingress direction. It does not support port ACLs in the egress direction on Layer 2 ports.

Use only the extended ACL syntax style to define the per-user configuration stored on the RADIUS server. When the definitions are passed from the RADIUS server, they are created by using the extended naming convention. However, if you use the Filter-Id attribute, it can point to a standard ACL.

You can use the Filter-Id attribute to specify an inbound or outbound ACL that is already configured on the switch. The attribute contains the ACL number followed by .in for ingress filtering or .out for egress filtering. If the RADIUS server does not allow the .in or .out syntax, the access list is applied to the outbound ACL by default. The user is marked unauthorized if the Filter-Id sent from the RADIUS server is not configured on the device. The Filter-Id attribute is supported only for IP ACLs numbered in the range of 1 to 199 (IP standard ACLs) and 1300 to 2699 (IP extended ACLs).

The maximum size of the per-user ACL is 4000 ASCII characters but is limited by the maximum size of RADIUS-server per-user ACLs.

You must meet the following prerequisites to configure per-user ACLs:

  • Enable AAA authentication.

  • Enable AAA authorization by using the network keyword to allow interface configuration from the RADIUS server.

  • Enable 802.1x authentication.

  • Configure the user profile and VSAs on the RADIUS server.

  • Configure the 802.1x port for single-host mode.


    Note

    Per-user ACLs are supported only in single-host mode.

802.1x Authentication with Downloadable ACLs and Redirect URLs

You can download ACLs and redirect URLs from a RADIUS server to the switch during 802.1x authentication or MAC authentication bypass of the host. You can also download ACLs during web authentication. A downloadable ACL is also referred to as a dACL.

If more than one host is authenticated and the host is in single-host, MDA, or multiple-authentication mode, the switch changes the source address of the ACL to the host IP address.

You can apply the ACLs and redirect URLs to all the devices connected to the 802.1x-enabled port.

If no ACLs are downloaded during 802.1x authentication, the switch applies the static default ACL on the port to the host. On a voice VLAN port configured in multi-auth or MDA mode, the switch applies the ACL only to the phone as part of the authorization policies.

The limit for dACL with stacking is 64 ACEs per dACL per port. The limit without stacking is the number of available TCAM entries which varies based on the other ACL features that are active.

The 802.1x and MAB authentication methods support two authentication modes, open and closed. If there is no static ACL on a port in closed authentication mode:

  • When the first host authenticates, the authorization policy is applied without IP address insertion.

  • When a second host is detected, the policies for the first host are refreshed, and policies for the first and subsequent sessions are enforced with IP address insertion.

If there is no static ACL on a port in open authentication mode:

  • Policies are enforced with IP address insertion to prevent security breaches.

To control access for hosts with no authorization policy, you can configure a directive. The supported values for the directive are open and default. When you configure the open directive, all traffic is allowed. The default directive subjects traffic to the access provided by the port. You can configure the directive either in the user profile on the AAA server or on the switch. To configure the directive on the AAA server, use the authz-directive =<open/default> global command. To configure the directive on the switch, use the epm access-control open global configuration command.


Note

The default value of the directive is default.

For a URL redirect ACL:

  • Packets that match a permit access control entry (ACE) rule are sent to the CPU for forwarding to the AAA server.

  • Packets that match a deny ACE rule are forwarded through the switch.

  • Packets that match neither the permit ACE rule or deny ACE rule are processed by the next dACL, and if there is no dACL, the packets hit the implicit-deny ACL and are dropped.

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.

IEEE 802.1x Authentication with MAC Authentication Bypass

You can configure the switch to authorize clients based on the client MAC address by using the MAC authentication bypass feature. For example, you can enable this feature on IEEE 802.1x ports connected to devices such as printers.

If IEEE 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 IEEE 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 IEEE 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. This process works for most client devices; however, it does not work for clients that use an alternate MAC address format. You can configure how MAB authentication is performed for clients with MAC addresses that deviate from the standard format or where the RADIUS configuration requires the user name and password to differ.

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 IEEE 802.1x supplicant, the switch does not unauthorize the client connected to the port. When re-authentication occurs, the switch uses the authentication or re-authentication methods configured on the port, 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 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

  • Voice VLAN

  • Private VLAN—You can assign a client to a private VLAN.

  • Network Edge Access Topology (NEAT)—MAB and NEAT are mutually exclusive. You cannot enable MAB when NEAT is enabled on an interface, and you should not enable NEAT when MAB is enabled on an interface.

MAC Authentication Bypass Configuration Guidelines

These are the MAC authentication bypass configuration guidelines:

  • Unless otherwise stated, the MAC authentication bypass guidelines are the same as the 802.1x authentication guidelines.

  • If you disable MAC authentication bypass from a port after the port has been authorized with its MAC address, the port state is not affected.

  • If the port is in the unauthorized state and the client MAC address is not the authentication-server database, the port remains in the unauthorized state. However, if the client MAC address is added to the database, the switch can use MAC authentication bypass to re-authorize the port.

  • If the port is in the authorized state, the port remains in this state until re-authorization occurs.

  • You can configure a timeout period for hosts that are connected by MAC authentication bypass but are inactive. The range is 1to 65535 seconds.

802.1x Multiple Authentication Mode

Multiple-authentication (multiauth) mode allows multiple authenticated clients on the data VLAN and voice VLAN. Each host is individually authenticated. There is no limit to the number of data or voice device that can be authenticated on a multiauthport.

If a hub or access point is connected to an 802.1x-enabled port, each connected client must be authenticated. For non-802.1x devices, you can use MAC authentication bypass or web authentication as the per-host authentication fallback method to authenticate different hosts with different methods on a single port.

You can assign a RADIUS-server-supplied VLAN in multi-auth mode, under the following conditions:

  • The host is the first host authorized on the port, and the RADIUS server supplies VLAN information

  • Subsequent hosts are authorized with a VLAN that matches the operational VLAN.

  • A host is authorized on the port with no VLAN assignment, and subsequent hosts either have no VLAN assignment, or their VLAN information matches the operational VLAN.

  • The first host authorized on the port has a group VLAN assignment, and subsequent hosts either have no VLAN assignment, or their group VLAN matches the group VLAN on the port. Subsequent hosts must use the same VLAN from the VLAN group as the first host. If a VLAN list is used, all hosts are subject to the conditions specified in the VLAN list.

  • After a VLAN is assigned to a host on the port, subsequent hosts must have matching VLAN information or be denied access to the port.

  • The behavior of the critical-auth VLAN is not changed for multi-auth mode. When a host tries to authenticate and the server is not reachable, all authorized hosts are reinitialized in the configured VLAN.

Multi-auth Per User VLAN assignment

The Multi-auth Per User VLAN assignment feature allows you to create multiple operational access VLANs based on VLANs assigned to the clients on the port that has a single configured access VLAN. The port configured as an access port where the traffic for all the VLANs associated with data domain is not dot1q tagged, and these VLANs are treated as native VLANs.

The number of hosts per multi-auth port is 8, however there can be more hosts.

The following scenarios are associated with the multi-auth Per User VLAN assignments:

Scenario One

When a hub is connected to an access port, and the port is configured with an access VLAN (V0).

The host (H1) is assigned to VLAN (V1) through the hub. The operational VLAN of the port is changed to V1. This behaviour is similar on a single-host or multi-domain-auth port.

When a second host (H2) is connected and gets assigned to VLAN ( V2), the port will have two operational VLANs (V1 and V2). If H1 and H2 sends untagged ingress traffic, H1 traffic is mapped to VLAN (V1) and H2 traffic to VLAN (V2), all egress traffic going out of the port on VLAN (V1) and VLAN (V2) are untagged.

If both the hosts, H1 and H2 are logged out or the sessions are removed due to some reason then VLAN (V1) and VLAN (V2) are removed from the port, and the configured VLAN (V0) is restored on the port.

Scenario Two

When a hub is connected to an access port, and the port is configured with an access VLAN (V0). The host (H1) is assigned to VLAN (V1) through the hub. The operational VLAN of the port is changed to V1.

When a second host (H2) is connected and gets authorized without explicit vlan policy, H2 is expected to use the configured VLAN (V0) that is restored on the port. A ll egress traffic going out of two operational VLANs, VLAN (V0) and VLAN (V1) are untagged.

If host (H2 ) is logged out or the session is removed due to some reason then the configured VLAN (V0) is removed from the port, and VLAN (V1) becomes the only operational VLAN on the port.

Scenario Three

When a hub is connected to an access port in open mode, and the port is configured with an access VLAN (V0) .

The host (H1) is assigned to VLAN (V1) through the hub. The operational VLAN of the port is changed to V1. When a second host (H2) is connected and remains unauthorized, it still has access to operational VLAN (V1) due to open mode.

If host H1 is logged out or the session is removed due to some reason, VLAN (V1) is removed from the port and host (H2) gets assigned to VLAN (V0).


Note

The combination of Open mode and VLAN assignment has an adverse affect on host (H2) because it has an IP address in the subnet that corresponds to VLAN (V1).

Limitation in Multi-Auth Per User VLAN assignment

In the Multi-Auth Per User VLAN Assignment feature, egress traffic from multiple VLANs are untagged on a port where the hosts receive traffic that is not meant for them. This can be a problem with broadcast and multicast traffic.

  • IPv4 ARPs: Hosts receive ARP packets from other subnets. This is a problem if two subnets in different Virtual Routing and Forwarding (VRF) tables with overlapping IP address range are active on the port. The host ARP cache may get invalid entries.

  • IPv6 Control Packets: In IPv6 deployments, Router Advertisements (RA) are processed by hosts that are not supposed to receive them. When a host from one VLAN receives RA from a different VLAN, the host assign incorrect IPv6 address to itself. Such a host is unable to get access to the network.

    The workaround is to enable the IPv6 first hop security so that the broadcast ICMPv6 packets are converted to unicast and sent out from multi-auth enabled ports.. The packet is replicated for each client in multi-auth port belonging to the VLAN and the destination MAC is set to an individual client. Ports having one VLAN, ICMPv6 packets broadcast normally.

  • IP Multicast: Multicast traffic destined to a multicast group gets replicated for different VLANs if the hosts on those VLANs join the multicast group. When two hosts in different VLANs join a multicast group (on the same mutli-auth port), two copies of each multicast packet are sent out from that port.

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:

  • Enter the authentication event no-response action authorize vlan vlan-id interface 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.

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.


Note

If an EAPOL packet is detected after the interface has changed to the guest VLAN, the interface reverts to an unauthorized state, and 802.1x authentication restarts.

Any number of 802.1x-incapable clients are allowed access when the switch port is moved to the guest VLAN. If an 802.1x-capable client joins the same port on which the guest VLAN is configured, the port is put into the unauthorized state in the user-configured access VLAN, and authentication is restarted.

Guest VLANs are supported on 802.1x ports in single host, multiple host, multi-auth and multi-domain modes.

You can configure any active VLAN except an RSPAN VLAN, a private VLAN, or a voice VLAN as an 802.1x guest VLAN. The guest VLAN feature is not supported on internal VLANs (routed ports) or trunk ports; it is supported only on access ports.

The switch supports MAC authentication bypass. When MAC authentication bypass is enabled on an 802.1x port, the switch can authorize clients based on the client MAC address when IEEE 802.1x authentication times out while waiting for an EAPOL message exchange. 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 specified.

802.1x Authentication with Restricted VLAN

You can configure a restricted VLAN (also referred to as an authentication failed VLAN) for each IEEE 802.1x port on a switch stack or a switch to provide limited services to clients that cannot access the guest VLAN. These clients are 802.1x-compliant and cannot access another VLAN because they fail the authentication process. A restricted VLAN allows users without valid credentials in an authentication server (typically, visitors to an enterprise) to access a limited set of services. The administrator can control the services available to the restricted VLAN.


Note

You can configure a VLAN to be both the guest VLAN and the restricted VLAN if you want to provide the same services to both types of users.

Without this feature, the client attempts and fails authentication indefinitely, and the switch port remains in the spanning-tree blocking state. With this feature, you can configure the switch port to be in the restricted VLAN after a specified number of authentication attempts (the default value is 3 attempts).

The authenticator counts the failed authentication attempts for the client. When this count exceeds the configured maximum number of authentication attempts, the port moves to the restricted VLAN. The failed attempt count increments when the RADIUS server replies with either an EAP failure or an empty response without an EAP packet. When the port moves into the restricted VLAN, the failed attempt counter resets.

Users who fail authentication remain in the restricted VLAN until the next re-authentication attempt. A port in the restricted VLAN tries to re-authenticate at configured intervals (the default is 60 seconds). If re-authentication fails, the port remains in the restricted VLAN. If re-authentication is successful, the port moves either to the configured VLAN or to a VLAN sent by the RADIUS server. You can disable re-authentication. If you do this, the only way to restart the authentication process is for the port to receive a link down or EAP logoff event. We recommend that you keep re-authentication enabled if a client might connect through a hub. When a client disconnects from the hub, the port might not receive the link down or EAP logoff event.

After a port moves to the restricted VLAN, a simulated EAP success message is sent to the client. This prevents clients from indefinitely attempting authentication. Some clients (for example, devices running Windows XP) cannot implement DHCP without EAP success.

Restricted VLANs are supported on 802.1x ports in all host modes and on Layer 2 ports.

You can configure any active VLAN except an RSPAN VLAN, a primary private VLAN, or a voice VLAN as an 802.1x restricted VLAN. The restricted VLAN feature is not supported on internal VLANs (routed ports) or trunk ports; it is supported only on access ports.

Other security port features such as dynamic ARP Inspection, DHCP snooping, and IP source guard can be configured independently on a restricted VLAN.

802.1x Authentication with Inaccessible Authentication Bypass

Use the inaccessible authentication bypass feature, also referred to as critical authentication or the AAA fail policy, when the switch cannot reach the configured RADIUS servers and new hosts cannot be authenticated. You can configure the switch to connect those hosts to critical ports.

When a new host tries to connect to the critical port, that host is moved to a user-specified access VLAN, the critical VLAN. The administrator gives limited authentication to the hosts.

When the switch tries to authenticate a host connected to a critical port, the switch checks the status of the configured RADIUS server. If a server is available, the switch can authenticate the host. However, if all the RADIUS servers are unavailable, the switch grants network access to the host and puts the port in the critical-authentication state, which is a special case of the authentication state.


Note

If critical authentication is configured on interface, then vlan used for critical authorization (critical vlan) should be active on the switch. If the critical vlan is inactive (or) down, critical authentication session will keep trying to enable inactive vlan and fail repeatedly. This can lead to large amount of memory holding.

Inaccessible Authentication Bypass Support on Multiple-Authentication Ports

When a port is configured on any host mode and the AAA server is unavailable, the port is then configured to multi-host mode and moved to the critical VLAN. To support this inaccessible bypass on multiple-authentication (multiauth) ports, use the authentication event server dead action reinitialize vlan vlan-id command. When a new host tries to connect to the critical port, that port is reinitialized and all the connected hosts are moved to the user-specified access VLAN.

This command is supported on all host modes.

Inaccessible Authentication Bypass Authentication Results

The behavior of the inaccessible authentication bypass feature depends on the authorization state of the port:

  • If the port is unauthorized when a host connected to a critical port tries to authenticate and all servers are unavailable, the switch puts the port in the critical-authentication state in the RADIUS-configured or user-specified access VLAN.

  • If the port is already authorized and reauthentication occurs, the switch puts the critical port in the critical-authentication state in the current VLAN, which might be the one previously assigned by the RADIUS server.

  • If the RADIUS server becomes unavailable during an authentication exchange, the current exchange times out, and the switch puts the critical port in the critical-authentication state during the next authentication attempt.

You can configure the critical port to reinitialize hosts and move them out of the critical VLAN when the RADIUS server is again available. When this is configured, all critical ports in the critical-authentication state are automatically re-authenticated.

Inaccessible Authentication Bypass Feature Interactions

Inaccessible authentication bypass interacts with these features:

  • Guest VLAN: Inaccessible authentication bypass is compatible with guest VLAN. When a guest VLAN is enabled on 8021.x port, the features interact as follows:

    • If at least one RADIUS server is available, the switch assigns a client 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.

    • If all the RADIUS servers are not available and the client is connected to a critical port, the switch authenticates the client and puts the critical port in the critical-authentication state in the RADIUS-configured or user-specified access VLAN.

    • If all the RADIUS servers are not available and the client is not connected to a critical port, the switch might not assign clients to the guest VLAN if one is configured.

    • If all the RADIUS servers are not available and if a client is connected to a critical port and was previously assigned to a guest VLAN, the switch keeps the port in the guest VLAN.

  • Restricted VLAN: If the port is already authorized in a restricted VLAN and the RADIUS servers are unavailable, the switch puts the critical port in the critical-authentication state in the restricted VLAN.

  • 802.1x accounting: Accounting is not affected if the RADIUS servers are unavailable.

  • Private VLAN: You can configure inaccessible authentication bypass on a private VLAN host port. The access VLAN must be a secondary private VLAN.

  • Voice VLAN: Inaccessible authentication bypass is compatible with voice VLAN, but the RADIUS-configured or user-specified access VLAN and the voice VLAN must be different.

  • Remote Switched Port Analyzer (RSPAN): Do not configure an RSPAN VLAN as the RADIUS-configured or user-specified access VLAN for inaccessible authentication bypass.

In a switch stack:

When a member switch is added to the stack, the active switch sends the member switch the server status.

VLAN Assignment, Guest VLAN, Restricted VLAN, and Inaccessible Authentication Bypass

These are the configuration guidelines for VLAN assignment, guest VLAN, restricted VLAN, and inaccessible authentication bypass:

  • When 802.1x authentication is enabled on a port, you cannot configure a port VLAN that is equal to a voice VLAN.

  • You can configure any VLAN except an RSPAN VLAN or a voice VLAN as an 802.1x guest VLAN. The guest VLAN feature is not supported on internal VLANs (routed ports) or trunk ports; it is supported only on access ports.

  • After you configure a guest VLAN for an 802.1x port to which a DHCP client is connected, you might need to get a host IP address from a DHCP server. You can change the settings for restarting the 802.1x authentication process on the switch before the DHCP process on the client times out and tries to get a host IP address from the DHCP server. Decrease the settings for the 802.1x authentication process (authentication timer inactivity and authentication timer reauthentication interface configuration commands). The amount to decrease the settings depends on the connected 802.1x client type.

  • When configuring the inaccessible authentication bypass feature, follow these guidelines:

    • The feature is supported on 802.1x port in single-host mode and multihosts mode.

    • If the client is running Windows XP and the port to which the client is connected is in the critical-authentication state, Windows XP might report that the interface is not authenticated.

    • If the Windows XP client is configured for DHCP and has an IP address from the DHCP server, receiving an EAP-Success message on a critical port might not re-initiate the DHCP configuration process.

    • You can configure the inaccessible authentication bypass feature and the restricted VLAN on an 802.1x port. If the switch tries to re-authenticate a critical port in a restricted VLAN and all the RADIUS servers are unavailable, switch changes the port state to the critical authentication state and remains in the restricted VLAN.

  • You can configure any VLAN except an RSPAN VLAN or a voice VLAN as an 802.1x restricted VLAN. The restricted VLAN feature is not supported on internal VLANs (routed ports) or trunk ports; it is supported only on access ports.

802.1x Critical Voice VLAN

When an IP phone connected to a port is authenticated by the Cisco Identity Services Engine (ISE), the phone is put into the voice domain. If the ISE is not reachable, the switch cannot determine if the device is a voice device. If the server is unavailable, the phone cannot access the voice network and therefore cannot operate.

For data traffic, you can configure inaccessible authentication bypass, or critical authentication, to allow traffic to pass through on the native VLAN when the server is not available. If the RADIUS authentication server is unavailable (down) and inaccessible authentication bypass is enabled, the switch grants the client access to the network and puts the port in the critical-authentication state in the RADIUS-configured or the user-specified access VLAN. When the switch cannot reach the configured RADIUS servers and new hosts cannot be authenticated, the switch connects those hosts to critical ports. A new host trying to connect to the critical port is moved to a user-specified access VLAN, the critical VLAN, and granted limited authentication.


Note

Dynamic assignment of critical voice VLAN is not supported with nested service templates. It causes the device to switch between VLANs continuously in a loop.

You can enter the authentication event server dead action authorize voice interface configuration command to configure the critical voice VLAN feature. When the ISE does not respond, the port goes into critical authentication mode. When traffic coming from the host is tagged with the voice VLAN, the connected device (the phone) is put in the configured voice VLAN for the port. The IP phones learn the voice VLAN identification through Cisco Discovery Protocol (Cisco devices) or through LLDP or DHCP.

You can configure the voice VLAN for a port by entering the switchport voice vlan vlan-id interface configuration command.

This feature is supported in multidomain and multi-auth host modes. Although you can enter the command when the switch in single-host or multi-host mode, the command has no effect unless the device changes to multidomain or multi-auth host mode.

IEEE 802.1x Authentication with Voice VLAN Ports

A voice VLAN port is a special access port associated with two VLAN identifiers:

  • VVID to carry voice traffic to and from the IP phone. The VVID is used to configure the IP phone connected to the port.

  • PVID to carry the data traffic to and from the workstation connected to the switch through the IP phone. The PVID is the native VLAN of the port.

The IP phone uses the VVID for its voice traffic, regardless of the authorization state of the port. This allows the phone to work independently of IEEE 802.1x authentication.

In single-host mode, only the IP phone is allowed on the voice VLAN. In multiple-hosts mode, additional clients can send traffic on the voice VLAN after a supplicant is authenticated on the PVID. When multiple-hosts mode is enabled, the supplicant authentication affects both the PVID and the VVID.

A voice VLAN port becomes active when there is a link, and the device MAC address appears after the first Cisco Discovery Protocol message from the IP phone. Cisco IP phones do not relay Cisco Discovery Protocol messages from other devices. As a result, if several IP phones are connected in series, the switch recognizes only the one directly connected to it. When IEEE 802.1x authentication is enabled on a voice VLAN port, the switch drops packets from unrecognized IP phones more than one hop away.

When IEEE 802.1x authentication is enabled on a switch port, you can configure an access port VLAN that is also a voice VLAN.

When IP phones are connected to an 802.1x-enabled switch port that is in single host mode, the switch grants the phones network access without authenticating them. We recommend that you use multidomain authentication (MDA) on the port to authenticate both a data device and a voice device, such as an IP phone


Note

If you enable IEEE 802.1x authentication on an access port on which a voice VLAN is configured and to which a Cisco IP Phone is connected, the Cisco IP phone loses connectivity to the switch for up to 30 seconds.

Flexible Authentication Ordering

You can use flexible authentication ordering to configure the order of methods that a port uses to authenticate a new host. The IEEE 802.1X Flexible Authentication feature supports three authentication methods:

  • dot1X—IEEE 802.1X authentication is a Layer 2 authentication method.

  • mab—MAC-Authentication Bypass is a Layer 2 authentication method.

  • webauth—Web authentication is a Layer 3 authentication method.

Using this feature, you can control which ports use which authentication methods, and you can control the failover sequencing of methods on those ports. For example, MAC authentication bypass and 802.1x can be the primary or secondary authentication methods, and web authentication can be the fallback method if either or both of those authentication attempts fail.

The IEEE 802.1X Flexible Authentication feature supports the following host modes:

  • multi-auth—Multiauthentication allows one authentication on a voice VLAN and multiple authentications on the data VLAN.

  • multi-domain—Multidomain authentication allows two authentications: one on the voice VLAN and one on the data VLAN.

Open1x Authentication

Open1x authentication allows a device access to a port before that device is authenticated. When open authentication is configured, a new host can pass traffic according to the access control list (ACL) defined on the port. After the host is authenticated, the policies configured on the RADIUS server are applied to that host.

You can configure open authentication with these scenarios:

  • Single-host mode with open authentication–Only one user is allowed network access before and after authentication.

  • MDA mode with open authentication–Only one user in the voice domain and one user in the data domain are allowed.

  • Multiple-hosts mode with open authentication–Any host can access the network.

  • Multiple-authentication mode with open authentication–Similar to MDA, except multiple hosts can be authenticated.


    Note

    If open authentication is configured, it takes precedence over other authentication controls. This means that if you use the authentication open interface configuration command, the port will grant access to the host irrespective of the authentication port-control interface configuration command.

Multidomain Authentication

The switch supports multidomain authentication (MDA), which allows both a data device and voice device, such as an IP phone, to authenticate on the same switch port. The port is divided into a data domain and a voice domain.


Note
For all host modes, the line protocol stays up before authorization when port-based authentication is configured.

MDA does not enforce the order of device authentication. However, for best results, we recommend that a voice device is authenticated before a data device on an MDA-enabled port.

Follow these guidelines for configuring MDA:

  • You must configure a switch port for MDA.

  • You must configure the voice VLAN for the IP phone when the host mode is set to multidomain.

  • Voice VLAN assignment on an MDA-enabled port is supported.

  • To authorize a voice device, the AAA server must be configured to send a Cisco Attribute-Value (AV) pair attribute with a value of device-traffic-class=voice. Without this value, the switch treats the voice device as a data device.


    Note

    When traffic-class=voice is downloaded from AAA servers as a service-template, a session will be created in DATA domain instead of VOICE domain.

  • The guest VLAN and restricted VLAN features only apply to the data devices on an MDA-enabled port. The switch treats a voice device that fails authorization as a data device.

  • If more than one device attempts authorization on either the voice or the data domain of a port, it is error disabled.

  • Until a device is authorized, the port drops its traffic. Non-Cisco IP phones or voice devices are allowed into both the data and voice VLANs. The data VLAN allows the voice device to contact a DHCP server to obtain an IP address and acquire the voice VLAN information. After the voice device starts sending on the voice VLAN, its access to the data VLAN is blocked.

  • A voice device MAC address that is binding on the data VLAN is not counted towards the port security MAC address limit.

  • MDA can use MAC authentication bypass as a fallback mechanism to allow the switch port to connect to devices that do not support IEEE 802.1x authentication.

  • When a data or a voice device is detected on a port, its MAC address is blocked until authorization succeeds. If the authorization fails, the MAC address remains blocked for 5 minutes.

  • If more than five devices are detected on the data VLAN or more than one voice device is detected on the voice VLAN while a port is unauthorized, the port is error disabled.

  • When a port host mode is changed from single- or multihost to multidomain mode, an authorized data device remains authorized on the port. However, a Cisco IP phone that has been allowed on the port voice VLAN is automatically removed and must be reauthenticated on that port.

  • Active fallback mechanisms such as guest VLAN and restricted VLAN remain configured after a port changes from single- or multihost mode to multidomain mode.

  • Switching a port host mode from multidomain to single- or multihost mode removes all authorized devices from the port.

  • If a data domain is authorized first and placed in the guest VLAN, non-IEEE 802.1x-capable voice devices need to tag their packets on the voice VLAN to trigger authentication.

  • We do not recommend per-user ACLs with an MDA-enabled port. An authorized device with a per-user ACL policy might impact traffic on both the voice and data VLANs of the port. If used, only one device on the port should enforce per-user ACLs.

802.1x Supplicant and Authenticator Switches with Network Edge Access Topology

The Network Edge Access Topology (NEAT) feature extends identity to areas outside the wiring closet (such as conference rooms). This allows any type of device to authenticate on the port.

  • 802.1x switch supplicant: You can configure a switch to act as a supplicant to another switch by using the 802.1x supplicant feature. This configuration is helpful in a scenario, where, for example, a switch is outside a wiring closet and is connected to an upstream switch through a trunk port. A switch configured with the 802.1x switch supplicant feature authenticates with the upstream switch for secure connectivity. Once the supplicant switch authenticates successfully the port mode changes from access to trunk in an authenticator switch. In a supplicant switch you must manually configure trunk when enabling CISP.

  • If the access VLAN is configured on the authenticator switch, it becomes the native VLAN for the trunk port after successful authentication.

In the default state, when you connect a supplicant switch to an authenticator switch that has BPDU guard enabled, the authenticator port could be error-disabled if it receives a Spanning Tree Protocol (STP) bridge protocol data unit (BPDU) packets before the supplicant switch has authenticated. You can control traffic exiting the supplicant port during the authentication period. Entering the dot1x supplicant controlled transient global configuration command temporarily blocks the supplicant port during authentication to ensure that the authenticator port does not shut down before authentication completes. If authentication fails, the supplicant port opens. Entering the no dot1x supplicant controlled transient global configuration command opens the supplicant port during the authentication period. This is the default behavior.

We strongly recommend using the dot1x supplicant controlled transientcommand on a supplicant switch when BPDU guard is enabled on the authenticator switch port with the spanning-tree bpduguard enable interface configuration command.


Note
If you globally enable BPDU guard on the authenticator switch by using the spanning-tree portfast bpduguard default global configuration command, entering the dot1x supplicant controlled transient command does not prevent the BPDU violation.

You can enable MDA or multiauth mode on the authenticator switch interface that connects to one more supplicant switches. Multihost mode is not supported on the authenticator switch interface.

When you reboot an authenticator switch with single-host mode enabled on the interface, the interface may move to err-disabled state before authentication. To recover from err-disabled state, flap the authenticator port to activate the interface again and initiate authentication.

Use the dot1x supplicant force-multicast global configuration command on the supplicant switch for Network Edge Access Topology (NEAT) to work in all host modes.

  • Host Authorization: Ensures that only traffic from authorized hosts (connecting to the switch with supplicant) is allowed on the network. The switches use Client Information Signalling Protocol (CISP) to send the MAC addresses connecting to the supplicant switch to the authenticator switch.

  • Auto enablement: Automatically enables trunk configuration on the authenticator switch, allowing user traffic from multiple VLANs coming from supplicant switches. Configure the cisco-av-pair as device-traffic-class=switch at the ISE. (You can configure this under the group or the user settings.)

    Figure 5. Authenticator and Supplicant Switch using CISP

1

Workstations (clients)

2

Supplicant switch (outside wiring closet)

3

Authenticator switch

4

Cisco ISE

5

Trunk port


Note

The switchport nonegotiate command is not supported on supplicant and authenticator switches with NEAT. This command should not be configured at the supplicant side of the topology. If configured on the authenticator side, the internal macros will automatically remove this command from the port.

802.1x User Distribution

You can configure 802.1x user distribution to load-balance users with the same group name across multiple different VLANs.

The VLANs are either supplied by the RADIUS server or configured through the switch CLI under a VLAN group name.

  • Configure the RADIUS server to send more than one VLAN name for a user. The multiple VLAN names can be sent as part of the response to the user. The 802.1x user distribution tracks all the users in a particular VLAN and achieves load balancing by moving the authorized user to the least populated VLAN.

  • Configure the RADIUS server to send a VLAN group name for a user. The VLAN group name can be sent as part of the response to the user. You can search for the selected VLAN group name among the VLAN group names that you configured by using the switch CLI. If the VLAN group name is found, the corresponding VLANs under this VLAN group name are searched to find the least populated VLAN. Load balancing is achieved by moving the corresponding authorized user to that VLAN.

    Whenever the RADIUS server sends a VLAN group name in the attribute as a result of authorization, the least populated VLAN out of the group is assigned to the end-user. In case of reauthentication (authentication session present) and CoA (session alive), the same VLAN is kept even if it is not the least populated VLAN in the group.


    Note

    The RADIUS server can send the VLAN information in any combination of VLAN-IDs, VLAN names, or VLAN groups.

802.1x User Distribution Configuration Guidelines

  • Confirm that at least one VLAN is mapped to the VLAN group.

  • You can map more than one VLAN to a VLAN group.

  • You can modify the VLAN group by adding or deleting a VLAN.

  • When you clear an existing VLAN from the VLAN group name, none of the authenticated ports in the VLAN are cleared, but the mappings are removed from the existing VLAN group.

  • If you clear the last VLAN from the VLAN group name, the VLAN group is cleared.

  • You can clear a VLAN group even when the active VLANs are mapped to the group. When you clear a VLAN group, none of the ports or users that are in the authenticated state in any VLAN within the group are cleared, but the VLAN mappings to the VLAN group are cleared.

Network Admission Control Layer 2 IEEE 802.1x Validation

The switch supports the Network Admission Control (NAC) Layer 2 IEEE 802.1x validation, which checks the antivirus condition or posture of endpoint systems or clients before granting the devices network access. With NAC Layer 2 IEEE 802.1x validation, you can do these tasks:

  • Download the Session-Timeout RADIUS attribute (Attribute[27]) and the Termination-Action RADIUS attribute (Attribute[29]) from the authentication server.

  • Set the number of seconds between re-authentication attempts as the value of the Session-Timeout RADIUS attribute (Attribute[27]) and get an access policy against the client from the RADIUS server.

  • Set the action to be taken when the switch tries to re-authenticate the client by using the Termination-Action RADIUS attribute (Attribute[29]). If the value is the DEFAULT or is not set, the session ends. If the value is RADIUS-Request, the re-authentication process starts.

  • Set the list of VLAN number or name or VLAN group name as the value of the Tunnel Group Private ID (Attribute[81]) and the preference for the VLAN number or name or VLAN group name as the value of the Tunnel Preference (Attribute[83]). If you do not configure the Tunnel Preference, the first Tunnel Group Private ID (Attribute[81]) attribute is picked up from the list.

  • View the NAC posture token, which shows the posture of the client, by using the show authentication privileged EXEC command.

  • Configure secondary private VLANs as guest VLANs.

Configuring NAC Layer 2 IEEE 802.1x validation is similar to configuring IEEE 802.1x port-based authentication except that you must configure a posture token on the RADIUS server.

Voice Aware 802.1x Security


Note
To use voice aware IEEE 802.1x authentication, the switch must be running the LAN base image.

You use the voice aware 802.1x security feature to configure the switch to disable only the VLAN on which a security violation occurs, whether it is a data or voice VLAN. In previous releases, when an attempt to authenticate the data client caused a security violation, the entire port shut down, resulting in a complete loss of connectivity.

You can use this feature in IP phone deployments where a PC is connected to the IP phone. A security violation found on the data VLAN results in the shutdown of only the data VLAN. The traffic on the voice VLAN flows through the switch without interruption.

Common Session ID

Authentication manager uses a single session ID (referred to as a common session ID) for a client no matter which authentication method is used. This ID is used for all reporting purposes, such as the show commands and MIBs. The session ID appears with all per-session syslog messages.

The session ID includes:

  • The IP address of the Network Access Device (NAD)

  • A monotonically increasing unique 32 bit integer

  • The session start time stamp (a 32 bit integer)

This example shows how the session ID appears in the output of the show authentication command. The session ID in this example is 160000050000000B288508E5: 


Device# show authentication sessions
Interface  MAC Address     Method   Domain   Status         Session ID
Fa4/0/4    0000.0000.0203  mab      DATA     Authz Success  160000050000000B288508E5

This is an example of how the session ID appears in the syslog output. The session ID in this example is also160000050000000B288508E5:


1w0d: %AUTHMGR-5-START: Starting 'mab' for client (0000.0000.0203) on Interface Fa4/0/4
AuditSessionID 160000050000000B288508E5
1w0d: %MAB-5-SUCCESS: Authentication successful for client (0000.0000.0203) on Interface
Fa4/0/4 AuditSessionID 160000050000000B288508E5
1w0d: %AUTHMGR-7-RESULT: Authentication result 'success' from 'mab' for client
(0000.0000.0203) on Interface Fa4/0/4 AuditSessionID 160000050000000B288508E5

The session ID is used by the NAD, the AAA server, and other report-analyzing applications to identify the client. The ID appears automatically. No configuration is required.

Maximum Number of Allowed Devices Per Port

This is the maximum number of devices allowed on an 802.1x-enabled port:

  • In single-host mode, only one device is allowed on the access VLAN. If the port is also configured with a voice VLAN, an unlimited number of Cisco IP phones can send and receive traffic through the voice VLAN.

  • In multidomain authentication (MDA) mode, one device is allowed for the access VLAN, and one IP phone is allowed for the voice VLAN.

  • In multihost mode, only one 802.1x supplicant is allowed on the port, but an unlimited number of non-802.1x hosts are allowed on the access VLAN. An unlimited number of devices are allowed on the voice VLAN.

How to Configure IEEE 802.1x Port-Based Authentication

Configuring 802.1x Authentication

To allow per-user ACLs or VLAN assignment, you must enable AAA authorization to configure the switch for all network-related service requests.

This is the 802.1x AAA process:

Before you begin

To configure 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.

Procedure

  Command or Action Purpose

Step 1

A user connects to a port on the switch.

Step 2

Authentication is performed.

Step 3

VLAN assignment is enabled, as appropriate, based on the RADIUS server configuration.

Step 4

The switch sends a start message to an accounting server.

Step 5

Re-authentication is performed, as necessary.

Step 6

The switch sends an interim accounting update to the accounting server that is based on the result of re-authentication.

Step 7

The user disconnects from the port.

Step 8

The switch sends a stop message to the accounting server.

Configuring 802.1x Port-Based Authentication

Perform these steps to configure 802.1x port-based authentication:

Procedure

  Command or Action Purpose

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} method1

Example:


Device(config)# aaa authentication dot1x default group radius

Creates an 802.1x authentication method list.

To create a default list that is used when a named list is not specified in the authentication command, use the default keyword followed by the method that is to be used 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 the group radius keywords are supported.

Step 5

dot1x system-auth-control

Example:


Device(config)# dot1x system-auth-control

Enables 802.1x authentication globally on the switch.

Step 6

aaa authorization network {default} group radius

Example:


Device(config)# aaa authorization network default group radius

(Optional) Configures the switch to use user-RADIUS authorization for all network-related service requests, such as per-user ACLs or VLAN assignment.

Step 7

radius server server name

Example:


Device(config)# radius server rsim address ipv4 124.2.2.12

(Optional) Specifies the IP address of the RADIUS server.

Step 8

address {ipv4 | ipv6} ip address

Example:


Device(config-radius-server)# address ipv4 10.0.1.12

Configures the IP address for the RADIUS server.

Step 9

key string

Example:


Device(config-radius-server)# key rad123

(Optional) Specifies the authentication and encryption key used between the switch and the RADIUS daemon running on the RADIUS server.

Step 10

exit

Example:


Device(config-radius-server)# exit

Exits the RADIUS server mode and enters the global configuration mode.

Step 11

interface interface-id

Example:


Device(config)# interface gigabitethernet 1/0/2

Specifies the port connected to the client that is to be enabled for IEEE 802.1x authentication, and enter interface configuration mode.

Step 12

switchport mode access

Example:


Device(config-if)# switchport mode access

(Optional) Sets the port to access mode only if you configured the RADIUS server in Step 6 and Step 7.

Step 13

authentication port-control auto

Example:


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

Enables 802.1x authentication on the port.

Step 14

dot1x pae authenticator

Example:


Device(config-if)# dot1x pae authenticator

Sets the interface Port Access Entity to act only as an authenticator and ignore messages meant for a supplicant.

Step 15

end

Example:


Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Configuring Periodic Re-Authentication

You can enable periodic 802.1x client re-authentication and specify how often it occurs. If you do not specify a time period before enabling re-authentication, the number of seconds between attempts is 3600.

Follow these steps to enable periodic re-authentication of the client and to configure the number of seconds between re-authentication attempts. This procedure is optional.

Procedure

  Command or Action Purpose

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

interface interface-id

Example:


Device(config)# interface gigabitethernet 2/0/1

Specifies the port to be configured, and enter interface configuration mode.

Step 4

authentication periodic

Example:


Device(config-if)# authentication periodic

Enables periodic re-authentication of the client, which is disabled by default.

Note

 

The default value is 3600 seconds. To change the value of the reauthentication timer or to have the switch use a RADIUS-provided session timeout, enter the authentication timer reauthenticate command.

Step 5

authentication timer {{[inactivity | reauthenticate | restart | unauthorized]} {value}}

Example:


Device(config-if)# authentication timer reauthenticate 180

Sets the number of seconds between re-authentication attempts.

The authentication timer keywords have these meanings:

  • inactivity —Interval in seconds after which if there is no activity from the client then it is unauthorized

  • reauthenticate —Time in seconds after which an automatic re-authentication attempt is initiated

  • restart value —Interval in seconds after which an attempt is made to authenticate an unauthorized port

  • unauthorized value —Interval in seconds after which an unauthorized session will get deleted

This command affects the behavior of the switch only if periodic re-authentication is enabled.

Step 6

end

Example:


Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Configuring 802.1x Violation Modes

You can configure an 802.1x port so that it shuts down, generates a syslog error, or discards packets from a new device when:

  • A device connects to an 802.1x-enabled port

  • The maximum number of allowed about devices have been authenticated on the port

Beginning in privileged EXEC mode, follow these steps to configure the security violation actions on the switch:

Procedure

  Command or Action Purpose

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} method1

Example:


Device(config)# aaa authentication dot1x default group radius

Creates an 802.1x authentication method list.

To create a default list that is used when a named list is not specified in the authentication command, use the default keyword followed by the method that is to be used 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.

Step 5

interface interface-type interface-number

Example:


Device(config)# interface gigabitethernet 1/0/4

Specifies the port connected to the client that is to be enabled for IEEE 802.1x authentication, and enter interface configuration mode.

Step 6

switchport mode access

Example:


Device(config-if)# switchport mode access

Sets the port to access mode.

Step 7

authentication violation {shutdown | restrict | protect | replace}

Example:


Device(config-if)# authentication violation restrict

Configures the violation mode. The keywords have these meanings:

  • shutdown –Error disable the port.

  • restrict –Generate a syslog error.

  • protect –Drop packets from any new device that sends traffic to the port.

  • replace –Removes the current session and authenticates with the new host.

Step 8

end

Example:


Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Changing the Quiet Period

When the switch cannot authenticate the client, the switch remains idle for a set period of time and then tries again. The authentication timer restart interface configuration command controls the idle period. A failed authentication of the client might occur because the client provided an invalid password. You can provide a faster response time to the user by entering a number smaller than the default.

Beginning in privileged EXEC mode, follow these steps to change the quiet period. This procedure is optional.

Procedure

  Command or Action Purpose

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

interface interface-id

Example:


Device(config)# interface gigabitethernet 2/0/1

Specifies the port to be configured, and enters interface configuration mode.

Step 4

authentication timer restart seconds

Example:


Device(config-if)# authentication timer restart 30

Sets the number of seconds that the switch remains in the quiet state following a failed authentication exchange with the client.

The range is 1 to 65535 seconds; the default is 60.

Step 5

end

Example:


Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Step 6

show authentication sessions interface interface-id

Example:


Device# show authentication sessions interface gigabitethernet2/0/1

Verifies your entries.

Step 7

copy running-config startup-config

Example:


Device# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Changing the Switch-to-Client Retransmission Time

The client responds to the EAP-request/identity frame from the switch with an EAP-response/identity frame. If the switch does not receive this response, it waits a set period of time (known as the retransmission time) and then resends the frame.


Note

You should change the default value of this command only to adjust for unusual circumstances such as unreliable links or specific behavioral problems with certain clients and authentication servers.

Beginning in privileged EXEC mode, follow these steps to change the amount of time that the switch waits for client notification. This procedure is optional.

Procedure

  Command or Action Purpose

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

interface interface-id

Example:


Device(config)# interface gigabitethernet2/0/1

Specifies the port to be configured, and enters interface configuration mode.

Step 4

authentication timer reauthenticate seconds

Example:


Device(config-if)# authentication timer reauthenticate 60

Sets the number of seconds that the switch waits for a response to an EAP-request/identity frame from the client before resending the request.

The range is 1 to 65535 seconds; the default is 5.

Step 5

end

Example:


Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Step 6

show authentication sessions interface interface-id

Example:


Device# show authentication sessions interface gigabitethernet 2/0/1

Verifies your entries.

Step 7

copy running-config startup-config

Example:


Device# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Setting the Switch-to-Client Frame-Retransmission Number

In addition to changing the switch-to-client retransmission time, you can change the number of times that the switch sends an EAP-request/identity frame (assuming no response is received) to the client before restarting the authentication process.


Note

You should change the default value of this command only to adjust for unusual circumstances such as unreliable links or specific behavioral problems with certain clients and authentication servers.

Beginning in privileged EXEC mode, follow these steps to set the switch-to-client frame-retransmission number. This procedure is optional.

Procedure

  Command or Action Purpose

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

interface interface-id

Example:


Device(config)# interface gigabitethernet2/0/1

Specifies the port to be configured, and enters interface configuration mode.

Step 4

dot1x max-reauth-req count

Example:


Device(config-if)# dot1x max-reauth-req 5

Sets the number of times that the switch sends an EAP-request/identity frame to the client before restarting the authentication process. The range is 1 to 10; the default is 2.

Step 5

end

Example:


Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Configuring the Host Mode

Beginning in privileged EXEC mode, follow these steps to allow multiple hosts (clients) on an IEEE 802.1x-authorized port that has the authentication port-control interface configuration command set to auto . Use the multi-domain keyword to configure and enable multidomain authentication (MDA), which allows both a host and a voice device, such as an IP phone (Cisco or non-Cisco), on the same switch port. This procedure is optional.

Procedure

  Command or Action Purpose

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

interface interface-id

Example:


Device(config)# interface gigabitethernet 2/0/1

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

Step 4

authentication host-mode [multi-auth | multi-domain | multi-host | single-host]

Example:


Device(config-if)# authentication host-mode multi-host

Allows multiple hosts (clients) on an 802.1x-authorized port.

The keywords have these meanings:

  • multi-auth –Allow multiple authenticated clients on both the voice VLAN and data VLAN.

    Note

     

    The multi-auth keyword is only available with the authentication host-mode command.

  • multi-host –Allow multiple hosts on an 802.1x-authorized port after a single host has been authenticated.

  • multi-domain –Allow both a host and a voice device, such as an IP phone (Cisco or non-Cisco), to be authenticated on an IEEE 802.1x-authorized port.

    Note

     

    You must configure the voice VLAN for the IP phone when the host mode is set to multi-domain .

Make sure that the authentication port-control interface configuration command is set to auto for the specified interface.

Step 5

end

Example:


Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Enabling MAC Move

MAC move allows an authenticated host to move from one port on the device to another.

Beginning in privileged EXEC mode, follow these steps to globally enable MAC move on the device. This procedure is optional.

Procedure

  Command or Action Purpose

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

authentication mac-move permit

Example:


Device(config)# authentication mac-move permit

Enables MAC move on the device. Default is deny.

In Session Aware Networking mode, the default CLI is access-session mac-move deny. To enable Mac Move in Session Aware Networking, use the no access-session mac-move global configuration command.

In legacy mode (IBNS 1.0), default value for mac-move is deny and in C3PL mode (IBNS 2.0) default value is permit .

Step 4

end

Example:


Device(config)# end

Exits global configuration mode and returns to privileged EXEC mode.

Enabling MAC Replace

MAC replace allows a host to replace an authenticated host on a port.

Beginning in privileged EXEC mode, follow these steps to enable MAC replace on an interface. This procedure is optional.

Procedure

  Command or Action Purpose

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

interface interface-id

Example:


Devic(config)# interface gigabitethernet2/0/2

Specifies the port to be configured, and enters interface configuration mode.

Step 4

authentication violation {protect | replace | restrict | shutdown}

Example:


Device(config-if)# authentication violation replace

Use the replace keyword to enable MAC replace on the interface. The port removes the current session and initiates authentication with the new host.

The other keywords have these effects:

  • protect : the port drops packets with unexpected MAC addresses without generating a system message.

  • restrict : violating packets are dropped by the CPU and a system message is generated.

  • shutdown : the port is error disabled when it receives an unexpected MAC address.

Step 5

end

Example:


Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Configuring 802.1x Accounting

Enabling AAA system accounting with 802.1x accounting allows system reload events to be sent to the accounting RADIUS server for logging. The server can then infer that all active 802.1x sessions are closed.


Note

Cisco IOS XE Everest 16.6.x, periodic AAA accounting updates are not supported. The switch does not send periodic interim accounting records to the accounting server. Periodic AAA accounting updates are available in Cisco IOS XE Fuji 16.9.x and later releases.

Because RADIUS uses the unreliable UDP transport protocol, accounting messages might be lost due to poor network conditions. If the switch does not receive the accounting response message from the RADIUS server after a configurable number of retransmissions of an accounting request, this system message appears: 


Accounting message %s for session %s failed to receive Accounting Response.

When the stop message is not sent successfully, this message appears:


00:09:55: %RADIUS-4-RADIUS_DEAD: RADIUS server 172.20.246.201:1645,1646 is not responding.

Note

You must configure the RADIUS server to perform accounting tasks, such as logging start, stop, and interim-update messages and time stamps. To turn on these functions, enable logging of “Update/Watchdog packets from this AAA client” in your RADIUS server Network Configuration tab. Next, enable “CVS RADIUS Accounting” in your RADIUS server System Configuration tab.

Beginning in privileged EXEC mode, follow these steps to configure 802.1x accounting after AAA is enabled on your switch. This procedure is optional.

Procedure

  Command or Action Purpose

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

interface interface-id

Example:


Device(config)# interface gigabitethernet 1/0/3

Specifies the port to be configured, and enters interface configuration mode.

Step 4

aaa accounting dot1x default start-stop group radius

Example:


Device(config-if)# aaa accounting dot1x default start-stop group radius

Enables 802.1x accounting using the list of all RADIUS servers.

Step 5

aaa accounting system default start-stop group radius

Example:


Device(config-if)# aaa accounting system default start-stop group radius

(Optional) Enables system accounting (using the list of all RADIUS servers) and generates system accounting reload event messages when the switch reloads.

Step 6

end

Example:


Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Configuring 802.1x Readiness Check

The 802.1x readiness check monitors 802.1x activity on all the switch ports and displays information about the devices connected to the ports that support 802.1x. You can use this feature to determine if the devices connected to the switch ports are 802.1x-capable.

The 802.1x readiness check is allowed on all ports that can be configured for 802.1x. The readiness check is not available on a port that is configured as dot1x force-unauthorized.

Follow these steps to enable the 802.1x readiness check on the switch:

Before you begin

Follow these guidelines to enable the readiness check on the switch:

  • The readiness check is typically used before 802.1x is enabled on the switch.

  • If you use the dot1x test eapol-capable privileged EXEC command without specifying an interface, all the ports on the switch stack are tested.

  • When you configure the dot1x test eapol-capable command on an 802.1x-enabled port, and the link comes up, the port queries the connected client about its 802.1x capability. When the client responds with a notification packet, it is 802.1x-capable. A syslog message is generated if the client responds within the timeout period. If the client does not respond to the query, the client is not 802.1x-capable. No syslog message is generated.

  • The readiness check can be sent on a port that handles multiple hosts (for example, a PC that is connected to an IP phone). A syslog message is generated for each of the clients that respond to the readiness check within the timer period.

Procedure

  Command or Action Purpose

Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

dot1x test eapol-capable [interface interface-id]

Example:

Device# dot1x test eapol-capable interface gigabitethernet1/0/13
DOT1X_PORT_EAPOL_CAPABLE:DOT1X: MAC 00-01-02-4b-f1-a3 on gigabitethernet1/0/13 is EAPOL 
capable

Enables the 802.1x readiness check on the switch.

(Optional) For interface-id specify the port on which to check for IEEE 802.1x readiness.

Note

 

If you omit the optional interface keyword, all interfaces on the switch are tested.

Step 3

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 4

dot1x test timeout timeout

Example:


Device(config)# dot1x test timeout 54

(Optional) Configures the timeout used to wait for EAPOL response. The range is from 1 to 65535 seconds. The default is 10 seconds.

Step 5

end

Example:


Device(config)# end

Exits global configuration mode and returns to privileged EXEC mode.

Configuring Switch-to-RADIUS-Server Communication

Follow these steps to configure the RADIUS server parameters:

Procedure

  Command or Action Purpose

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

ip radius source-interface vlan vlan interface number

Example:


Device(config)# ip radius source-interface vlan 80

Specifies that the RADIUS packets have the IP address of the indicated interface.

Step 4

radius server server name

Example:


Device(config)# radius server rsim address ipv4 172.16.0.1

(Optional) Specifies the IP address of the RADIUS server.

Step 5

address {ipv4 | ipv6} ip address

Example:


Device(config-radius-server)# address ipv4 10.0.1.2 auth-port 1550 acct-port 1560

Configures the IP address for the RADIUS server.

Step 6

key string

Example:


Device(config-radius-server)# key rad123

(Optional) Specifies the authentication and encryption key used between the switch and the RADIUS daemon running on the RADIUS server.

Step 7

exit

Example:


Device(config-radius-server)# exit

Exits the RADIUS server mode and enters the global configuration mode.

Step 8

radius-server dead-criteria tries num-tries

Example:


Device(config)# radius-server dead-criteria tries 30

Specifies the number of unanswered sent messages to a RADIUS server before considering the server to be inactive. The range of num-tries is 1 to 100.

Step 9

end

Example:


Device(config)# end

Exits global configuration mode and returns to privileged EXEC mode.

Setting the Re-Authentication Number

You can also change the number of times that the device restarts the authentication process before the port changes to the unauthorized state.


Note

You should change the default value of this command only to adjust for unusual circumstances such as unreliable links or specific behavioral problems with certain clients and authentication servers.

Beginning in privileged EXEC mode, follow these steps to set the re-authentication number. This procedure is optional.

Procedure

  Command or Action Purpose

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

interface interface-id

Example:


Device# interface gigabitethernet2/0/1

Specifies the port to be configured, and enters interface configuration mode.

Step 4

switchport mode access

Example:


Device(config-if)# switchport mode access

Sets the port to access mode only if you previously configured the RADIUS server.

Step 5

dot1x max-req count

Example:


Device(config-if)# dot1x max-req 4

Sets the number of times that the device restarts the authentication process before the port changes to the unauthorized state. The range is 0 to 10; the default is 2.

Step 6

end

Example:


Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Configuring a Guest VLAN

When you configure a guest VLAN, clients that are not 802.1x-capable are put into the guest VLAN when the server does not receive a response to its EAP request/identity frame. Clients that are 802.1x-capable but that fail authentication are not granted network access. The switch supports guest VLANs in single-host or multiple-hosts mode.

Beginning in privileged EXEC mode, follow these steps to configure a guest VLAN. This procedure is optional.

Procedure

  Command or Action Purpose

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

interface interface-id

Example:


Device(config)# interface gigabitethernet 2/0/2

Specifies the port to be configured, and enters interface configuration mode.

Step 4

dot1x port-control auto

Example:


Device(config-if)# dot1x port-control auto

Enables 802.1x authentication on the port.

Step 5

authentication event no-response action authorize vlan vlan-id

Example:


Device(config-if)# authentication event no-response action authorize vlan 2

Specifies an active VLAN as an 802.1x guest VLAN. The range is 1 to 4094.

You can configure any active VLAN except an internal VLAN (routed port), an RSPAN VLAN or a voice VLAN as an 802.1x guest VLAN.

Step 6

end

Example:


Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Configuring a Restricted VLAN

When you configure a restricted VLAN on a device, clients that are IEEE 802.1x-compliant are moved into the restricted VLAN when the authentication server does not receive a valid username and password. The device supports restricted VLANs only in single-host mode.

Beginning in privileged EXEC mode, follow these steps to configure a restricted VLAN. This procedure is optional.

Procedure

  Command or Action Purpose

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

interface interface-id

Example:


Device(config)# interface gigabitethernet 2/0/2

Specifies the port to be configured, and enters interface configuration mode.

Step 4

authentication port-control auto

Example:


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

Enables 802.1x authentication on the port.

Step 5

authentication event fail action authorize vlan vlan-id

Example:


Device(config-if)# authentication event fail action authorize vlan 2

Specifies an active VLAN as an 802.1x restricted VLAN. The range is 1 to 4094.

You can configure any active VLAN except an internal VLAN (routed port), an RSPAN VLAN or a voice VLAN as an 802.1x restricted VLAN.

Step 6

end

Example:


Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Configuring Number of Authentication Attempts on a Restricted VLAN

You can configure the maximum number of authentication attempts allowed before a user is assigned to the restricted VLAN by using the authentication event fail retry retry count interface configuration command. The range of allowable authentication attempts is 1 to 3. The default is 3 attempts.

Beginning in privileged EXEC mode, follow these steps to configure the maximum number of allowed authentication attempts. This procedure is optional.

Procedure
  Command or Action Purpose

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

interface interface-id

Example:

Device(config)# interface gigabitethernet 2/0/3

Specifies the port to be configured, and enters interface configuration mode.

Step 4

authentication port-control auto

Example:

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

Enables 802.1x authentication on the port.

Step 5

authentication event fail action authorize vlan vlan-id

Example:

Device(config-if)# authentication event fail action authorize vlan 8

Specifies an active VLAN as an 802.1x restricted VLAN. The range is 1 to 4094.

You can configure any active VLAN except an internal VLAN (routed port), an RSPAN VLAN or a voice VLAN as an 802.1x restricted VLAN.

Step 6

authentication event fail retry retry count

Example:

Device(config-if)# authentication event fail retry 2

Step 7

end

Example:

Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Configuring 802.1x Inaccessible Authentication Bypass with Critical Voice VLAN

Beginning in privileged EXEC mode, follow these steps to configure critical voice VLAN on a port and enable the inaccessible authentication bypass feature.

Procedure

  Command or Action Purpose

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

radius-server dead-criteria{time seconds } [tries number]

Example:


Device(config)# radius-server dead-criteria time 20 tries 10

Sets the conditions that determine when a RADIUS server is considered un-available or down (dead).

  • time— 1 to 120 seconds. The switch dynamically determines a default seconds value between 10 and 60.

  • number—1 to 100 tries. The switch dynamically determines a default triesnumber between 10 and 100.

Step 5

radius-serverdeadtimeminutes

Example:


Device(config)# radius-server deadtime 60

(Optional) Sets the number of minutes during which a RADIUS server is not sent requests. The range is from 0 to 1440 minutes (24 hours). The default is 0 minutes.

Step 6

radius server server name

Example:


Device(config)# radius server rsim address ipv4 124.2.2.12

(Optional) Specifies the IP address of the RADIUS server.

Step 7

address {ipv4 | ipv6} ip address auth-port port_number acct-port port_number

Example:


Device(config-radius-server)# address ipv4 10.0.1.2 auth-port 1550 acct-port 1560

Configures the IP address for the RADIUS server.

Step 8

key string

Example:


Device(config-radius-server)# key rad123

(Optional) Specifies the authentication and encryption key used between the switch and the RADIUS daemon running on the RADIUS server.

Step 9

exit

Example:


Device(config-radius-server)# exit

Exits the RADIUS server mode and enters the global configuration mode.

Step 10

dot1x critical {eapol | recovery delay milliseconds}

Example:


Device(config)# dot1x critical eapol

Device(config)# dot1x critical recovery delay 2000

(Optional) Configure the parameters for inaccessible authentication bypass:

  • eapol—Specify that the switch sends an EAPOL-Success message when the switch successfully authenticates the critical port.

  • recovery delaymilliseconds—Set the recovery delay period during which the switch waits to re-initialize a critical port when a RADIUS server that was unavailable becomes available. The range is from 1 to 10000 milliseconds. The default is 1000 milliseconds (a port can be re-initialized every second).

Step 11

interface interface-id

Example:


Device(config)# interface gigabitethernet 1/0/1

Specify the port to be configured, and enters interface configuration mode.

Step 12

authentication event server dead action {authorize | reinitialize} vlan vlan-id]

Example:


Device(config-if)# authentication event server dead action 
reinitialicze vlan 20

Use these keywords to move hosts on the port if the RADIUS server is unreachable:

  • authorize—Move any new hosts trying to authenticate to the user-specified critical VLAN.

  • reinitialize—Move all authorized hosts on the port to the user-specified critical VLAN.

Step 13

switchport voice vlan vlan-id

Example:


Device(config-if)# switchport voice vlan

Specifies the voice VLAN for the port. The voice VLAN cannot be the same as the critical data VLAN configured in Step 6.

Step 14

authentication event server dead action authorize voice

Example:


Device(config-if)#  authentication event server dead action 
authorize voice

Configures critical voice VLAN to move data traffic on the port to the voice VLAN if the RADIUS server is unreachable.

Step 15

end

Example:


Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Step 16

show authentication interface interface-id

Example:


Device(config-if)# show authentication interface gigabitethernet 1/0/1

(Optional) Verify your entries.

Example

To return to the RADIUS server default settings, use the no radius-server dead-criteria, the no radius-server deadtime, and the no radius server global configuration commands. To disable inaccessible authentication bypass, use the no authentication event server dead action interface configuration command. To disable critical voice VLAN, use the no authentication event server dead action authorize voice interface configuration command.

Configuring MAC Authentication Bypass

Beginning in privileged EXEC mode, follow these steps to enable MAC authentication bypass. This procedure is optional.

Procedure

  Command or Action Purpose

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

interface interface-id

Example:


Device(config)# interface gigabitethernet 2/0/1

Specifies the port to be configured, and enters interface configuration mode.

Step 4

authentication port-control auto

Example:


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

Enables 802.1x authentication on the port.

Step 5

mab [eap]

Example:


Device(config-if)# mab

Enables MAC authentication bypass.

(Optional) Use the eap keyword to configure the device to use EAP for authorization.

Step 6

end

Example:


Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Configuring 802.1x User Distribution

Beginning in privileged EXEC mode, follow these steps to configure a VLAN group and to map a VLAN to it:

Procedure

  Command or Action Purpose

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

vlan group vlan-group-name vlan-list vlan-list

Example:


Device(config)# vlan group eng-dept vlan-list 10

Configures a VLAN group, and maps a single VLAN or a range of VLANs to it.

Step 4

no vlan group vlan-group-name vlan-list vlan-list

Example:


Device(config)# no vlan group eng-dept vlan-list 10

Clears the VLAN group configuration or elements of the VLAN group configuration.

Step 5

end

Example:


Device(config)# end

Exits global configuration mode and returns to privileged EXEC mode.

Configuring NAC Layer 2 802.1x Validation

You can configure NAC Layer 2 802.1x validation, which is also referred to as 802.1x authentication with a RADIUS server.

Beginning in privileged EXEC mode, follow these steps to configure NAC Layer 2 802.1x validation. The procedure is optional.

Procedure

  Command or Action Purpose

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

interface interface-id

Example:


Device(config)# interface gigabitethernet2/0/3

Specifies the port to be configured, and enters interface configuration mode.

Step 4

switchport mode access

Example:


Device(config-if)# switchport mode access

Sets the port to access mode only if you configured the RADIUS server.

Step 5

authentication event no-response action authorize vlan vlan-id

Example:


Device(config-if)# authentication event no-response action authorize vlan 8

Specifies an active VLAN as an 802.1x guest VLAN. The range is 1 to 4094.

You can configure any active VLAN except an internal VLAN (routed port), an RSPAN VLAN, or a voice VLAN as an 802.1x guest VLAN.

Step 6

authentication periodic

Example:


Device(config-if)# authentication periodic

Enables periodic re-authentication of the client, which is disabled by default.

Step 7

authentication timer reauthenticate

Example:


Device(config-if)# authentication timer reauthenticate

Sets re-authentication attempt for the client (set to one hour).

This command affects the behavior of the switch only if periodic re-authentication is enabled.

Step 8

end

Example:


Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Step 9

show authentication sessions interface interface-id

Example:


Device# show authentication sessions interface gigabitethernet2/0/3

Displays information about current Auth Manager sessions on the interface.

Configuring an Authenticator Switch with NEAT

Configuring this feature requires that one switch outside a wiring closet is configured as a supplicant and is connected to an authenticator switch.


Note

  • The authenticator switch interface configuration must be restored to access mode by explicitly flapping it if a line card is removed and inserted in the chassis when CISP or NEAT session is active.

  • The cisco-av-pairs must be configured as device-traffic-class=switch on the ISE, which sets the interface as a trunk after the supplicant is successfully authenticated.

Beginning in privileged EXEC mode, follow these steps to configure a switch as an authenticator:

Procedure

  Command or Action Purpose

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

cisp enable

Example:


Device(config)# cisp enable

Enables CISP.

Step 4

interface interface-id

Example:


Device(config)# interface gigabitethernet 2/0/1

Specifies the port to be configured, and enters interface configuration mode.

Step 5

switchport mode access

Example:


Device(config-if)# switchport mode access

Sets the port mode to access .

Step 6

authentication port-control auto

Example:


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

Sets the port-authentication mode to auto.

Step 7

dot1x pae authenticator

Example:


Device(config-if)# dot1x pae authenticator

Configures the interface as a port access entity (PAE) authenticator.

Step 8

spanning-tree portfast

Example:


Device(config-if)# spanning-tree portfast trunk

Enables Port Fast on an access port connected to a single workstation or server..

Step 9

end

Example:


Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Configuring a Supplicant Switch with NEAT

Beginning in privileged EXEC mode, follow these steps to configure a switch as a supplicant:

Procedure

  Command or Action Purpose

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

cisp enable

Example:


Device(config)# cisp enable

Enables CISP.

Step 4

dot1x credential s profile

Example:


Device(config)# dot1x credentials test

Creates 802.1x credentials profile. This must be attached to the port that is configured as supplicant.

Step 5

username suppswitch

Example:


Device(config)# username suppswitch

Creates a username.

Step 6

password password

Example:


Device(config)# password myswitch

Creates a password for the new username.

Step 7

dot1x supplicant force-multicast

Example:


Device(config)# dot1x supplicant force-multicast

Forces the switch to send only multicast EAPOL packets when it receives either unicast or multicast packets.

This also allows NEAT to work on the supplicant switch in all host modes.

Step 8

interface interface-id

Example:


Device(config)# interface gigabitethernet1/0/1

Specifies the port to be configured, and enters interface configuration mode.

Step 9

switchport trunk encapsulation dot1q

Example:


Device(config-if)# switchport trunk encapsulation dot1q

Sets the port to trunk mode.

Step 10

switchport mode trunk

Example:


Device(config-if)# switchport mode trunk

Configures the interface as a VLAN trunk port.

Step 11

dot1x pae supplicant

Example:


Device(config-if)# dot1x pae supplicant

Configures the interface as a port access entity (PAE) supplicant.

Step 12

dot1x credentials profile-name

Example:


Device(config-if)# dot1x credentials test

Attaches the 802.1x credentials profile to the interface.

Step 13

end

Example:


Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Configuring 802.1x Authentication with Downloadable ACLs and Redirect URLs


Note

You must configure a downloadable ACL on the ACS before downloading it to the switch.

After authentication on the port, you can use the show ip access-list privileged EXEC command to display the downloaded ACLs on the port.


Note

The output of the show ip access-lists interface command does not display dACL or ACL filter IDs. This is because the ACLs are attached to the virtual ports created by multidomain authentication for each authentication session; instead of the physical interface. To display dACL or ACL filter IDs, use the show ip access-lists access-list-name command. The access-list-name should be taken from the show access-session interface interface-name detail command output. The access-list-name is case sensitive.

Configuring Downloadable ACLs

The policies take effect after client authentication and the client IP address addition to the IP device tracking table. The switch then applies the downloadable ACL to the port.

Beginning in privileged EXEC mode:

Before you begin

SISF-Based device tracking is a prerequisite to configuring 802.1x authentication. Ensure that you have enabled device tracking programmatically or manually. For more information, see the Confguring SISF-Based Tracking chapter.

Procedure
  Command or Action Purpose

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 authorization network default local group radius

Example:

Device(config)# aaa authorization network default local group radius

Sets the authorization method to local. To remove the authorization method, use the no aaa authorization network default local group radius command.

Step 5

radius-server vsa send authentication

Example:

Device(config)# radius-server vsa send authentication

Configures the radius vsa send authentication.

Step 6

interface interface-id

Example:

Device(config)# interface gigabitethernet2/0/4

Specifies the port to be configured, and enters interface configuration mode.

Step 7

ip access-group acl-id in

Example:

Device(config-if)# ip access-group default_acl in

Configures the default ACL on the port in the input direction.

Note

 

The acl-id is an access list name or number.

Step 8

end

Example:

Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Configuring a Downloadable Policy

Before you begin

SISF-Based device tracking is a prerequisite to configuring 802.1x authentication. Ensure that you have enabled device tracking programmatically or manually.

Procedure
  Command or Action Purpose

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

access-list access-list-number { deny | permit } { hostname | any | host } log

Example:
Device(config)# access-list 1 deny any log

Defines the default port ACL.

The access-list-number is a decimal number from 1 to 99 or 1300 to 1999.

Enter deny or permit to specify whether to deny or permit access if conditions are matched.

The source is the source address of the network or host that sends a packet, such as this:

  • hostname: The 32-bit quantity in dotted-decimal format.

  • any: The keyword any as an abbreviation for source and source-wildcard value of 0.0.0.0 255.255.255.255. You do not need to enter a source-wildcard value.

  • host: The keyword host as an abbreviation for source and source-wildcard of source 0.0.0.0.

(Optional) Applies the source-wildcard wildcard bits to the source.

(Optional) Enters log to cause an informational logging message about the packet that matches the entry to be sent to the console.

Step 4

interface interface-id

Example:

Device(config)# interface gigabitethernet 2/0/2

Enters interface configuration mode.

Step 5

ip access-group acl-id in

Example:

Device(config-if)# ip access-group default_acl in

Configures the default ACL on the port in the input direction.

Note

 

The acl-id is an access list name or number.

Step 6

exit

Example:

Device(config-if)# exit

Exits interface configuration mode and returns to global configuration mode.

Step 7

aaa new-model

Example:

Device(config)# aaa new-model

Enables AAA.

Step 8

aaa authorization network default group radius

Example:

Device(config)# aaa authorization network default group radius

Sets the authorization method to local. To remove the authorization method, use the no aaa authorization network default group radius command.

Step 9

radius-server vsa send authentication

Example:

Device(config)# radius-server vsa send authentication

Configures the network access server to recognize and use vendor-specific attributes.

Note

 

The downloadable ACL must be operational.

Step 10

end

Example:

Device(config)# end

Exits global configuration mode and returns to privileged EXEC mode.

Configuring VLAN ID Based MAC Authentication

Beginning in privileged EXEC mode, follow these steps:

Procedure

  Command or Action Purpose

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

mab request format attribute 32 vlan access-vlan

Example:


Device(config)# mab request format attribute 32 vlan access-vlan

Enables VLAN ID-based MAC authentication.

Step 4

end

Example:


Device(config)# end

Exits global configuration mode and returns to privileged EXEC mode.

Configuring Flexible Authentication Ordering

The examples used in the instructions below changes the order of Flexible Authentication Ordering so that MAB is attempted before IEEE 802.1X authentication (dot1x). MAB is configured as the first authentication method, so MAB will have priority over all other authentication methods.

Beginning in privileged EXEC mode, follow these steps:

Procedure

  Command or Action Purpose

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

interface interface-id

Example:


Device(config)# interface gigabitethernet 1/0/1

Specifies the port to be configured, and enters interface configuration mode.

Step 4

switchport mode access

Example:


Device(config-if)# switchport mode access

Sets the port to access mode only if you previously configured the RADIUS server.

Step 5

authentication order [ dot1x | mab ] | {webauth}

Example:


Device(config-if)# authentication order mab dot1x

(Optional) Sets the order of authentication methods used on a port.

Step 6

authentication priority [ dot1x | mab ] | {webauth}

Example:


Device(config-if)# authentication priority mab dot1x

(Optional) Adds an authentication method to the port-priority list.

Step 7

end

Example:


Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Configuring Open1x

Beginning in privileged EXEC mode, follow these steps to enable manual control of the port authorization state:

Procedure

  Command or Action Purpose

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

interface interface-id

Example:


Device(config)# interface gigabitethernet 1/0/1

Specifies the port to be configured, and enters interface configuration mode.

Step 4

switchport mode access

Example:


Device(config-if)# switchport mode access

Sets the port to access mode only if you configured the RADIUS server.

Step 5

authentication control-direction {both | in}

Example:


Device(config-if)# authentication control-direction both

(Optional) Configures the port control as unidirectional or bidirectional.

Step 6

authentication fallback name

Example:


Device(config-if)# authentication fallback profile1

(Optional) Configures a port to use web authentication as a fallback method for clients that do not support 802.1x authentication.

Step 7

authentication host-mode [multi-auth | multi-domain | multi-host | single-host]

Example:


Device(config-if)# authentication host-mode multi-auth

(Optional) Sets the authorization manager mode on a port.

Step 8

authentication open

Example:


Device(config-if)# authentication open

(Optional) Enables or disable open access on a port.

Step 9

authentication order [ dot1x | mab ] | {webauth}

Example:


Device(config-if)# authentication order dot1x webauth

(Optional) Sets the order of authentication methods used on a port.

Step 10

authentication periodic

Example:


Device(config-if)# authentication periodic

(Optional) Enables or disable reauthentication on a port.

Step 11

authentication port-control {auto | force-authorized | force-un authorized}

Example:


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

(Optional) Enables manual control of the port authorization state.

Step 12

end

Example:


Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Disabling 802.1x Authentication on a Port

You can disable 802.1x authentication on the port by using the no dot1x pae interface configuration command.

Beginning in privileged EXEC mode, follow these steps to disable 802.1x authentication on the port. This procedure is optional.

Procedure

  Command or Action Purpose

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

interface interface-id

Example:


Device(config)# interface gigabitethernet 2/0/1

Specifies the port to be configured, and enters interface configuration mode.

Step 4

switchport mode access

Example:


Device(config-if)# switchport mode access

(Optional) Sets the port to access mode only if you configured the RADIUS server.

Step 5

no dot1x pae authenticator

Example:


Device(config-if)# no dot1x pae authenticator

Disables 802.1x authentication on the port.

Step 6

end

Example:


Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Resetting the 802.1x Authentication Configuration to Default Values

Beginning in privileged EXEC mode, follow these steps to reset the 802.1x authentication configuration to the default values. This procedure is optional.

Procedure

  Command or Action Purpose

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

interface interface-id

Example:


Device(config)# interface gigabitethernet 1/0/2

Enters interface configuration mode, and specifies the port to be configured.

Step 4

dot1x default

Example:


Device(config-if)# dot1x default

Resets the 802.1x parameters to the default values.

Step 5

end

Example:


Device(config-if)# end

Exits interface configuration mode and returns to privileged EXEC mode.

Configuring Voice-Aware 802.1x Security

You use the voice aware 802.1x security feature on the device to disable only the VLAN on which a security violation occurs, whether it is a data or voice VLAN. You can use this feature in IP phone deployments where a PC is connected to the IP phone. A security violation found on the data VLAN results in the shutdown of only the data VLAN. The traffic on the voice VLAN flows through the device without interruption.

Follow these guidelines to configure voice aware 802.1x voice security on the device:

  • You enable voice aware 802.1x security by entering the errdisable detect cause security-violation shutdown vlan global configuration command. You disable voice aware 802.1x security by entering the no version of this command. This command applies to all 802.1x-configured ports in the device.


    Note

    If you do not include the shutdown vlan keywords, the entire port is shut down when it enters the error-disabled state.

  • If you use the errdisable recovery cause security-violation global configuration command to configure error-disabled recovery, the port is automatically re-enabled. If error-disabled recovery is not configured for the port, you re-enable it by using the shutdown and no shutdown interface configuration commands.

  • You can re-enable individual VLANs by using the clear errdisable interface interface-id vlan [vlan-list] privileged EXEC command. If you do not specify a range, all VLANs on the port are enabled.

Follow these steps to enable voice aware 802.1x security:

Procedure

  Command or Action Purpose

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

errdisable detect cause security-violation shutdown vlan

Example:


Device(config)# errdisable detect cause security-violation shutdown vlan

Shut down any VLAN on which a security violation error occurs.

Note

 
If the shutdown vlan keywords are not included, the entire port enters the error-disabled state and shuts down.

Step 4

errdisable recovery cause security-violation

Example:


Device(config)# errdisable recovery cause security-violation
Enables the automatic recovery of ports that were disabled because of 802.1X security violations..

Step 5

Enter the following:

  • shutdown
  • no shutdown

Example:


Device(config)# no shutdown
(Optional) Re-enables an error-disabled VLAN, and clear all error-disable indications.

Step 6

exit

Example:


Device(config)# exit

Exits global configuration mode and returns to privileged EXEC mode.

Step 7

clear errdisable interfaceinterface-id vlan [vlan-list]

Example:


Device# clear errdisable interface gigabitethernet 0/1/1 vlan vlan_list
(Optional) Reenables individual VLANs that have been error disabled.

  • For the interface-id argument, specify the port on which to reenable individual VLANs.

  • (Optional) For the vlan-list argument, specify a list of VLANs to be re-enabled. If vlan-list is not specified, all VLANs are re-enabled.

Step 8

show errdisable detect

Example:


Device# show errdisable detect
Displays the error-disabled detection status.

Configuration Examples for IEEE 802.1x Port-Based Authentication

The following sections provide configuration examples for IEEE 802.1x port-based authentication.

Example: Configuring Inaccessible Authentication Bypass

This example shows how to configure the Inaccessible Authentication Bypass feature:


Device> enable
Device# configure terminal
Device(config)# radius-server dead-criteria time 30 tries 20
Device(config)# radius-server deadtime 60
Device(config)# radius server server1
Device(config-radius-server)# address ipv4 172.29.36.49 acct-port 1618 auth-port 1612
Device(config-radius-server)# key abc1234
Device(config-radius-server)# exit
Device(config)# dot1x critical eapol
Device(config)# dot1x critical recovery delay 2000
Device(config)# interface gigabitethernet 1/0/1
Device(config-if)# dot1x critical
Device(config-if)# dot1x critical recovery action reinitialize
Device(config-if)# dot1x critical vlan 20
Device(config-if)# end

Example: Configuring VLAN Groups

This example shows how to configure VLAN groups, map VLANs to groups, and verify VLAN group configurations and mappings to specified VLANs: 

Device> enable
Device(config)# vlan group eng-dept vlan-list 10
Device(config)# exit
Device# show vlan group group-name eng-dept

Group Name                      Vlans Mapped
-------------                   --------------
eng-dept                        10

Device# show dot1x vlan-group all

Group Name                      Vlans Mapped
-------------                   --------------
eng-dept                        10
hr-dept                         20

This example shows how to add a VLAN to an existing VLAN group and to verify that the VLAN is added:

Device> enable
Device(config)# vlan group eng-dept vlan-list 30
Device(config)# exit
Device(config)# show vlan group eng-dept

Group Name                      Vlans Mapped
-------------                   --------------
eng-dept                        10,30

This example shows how to remove a VLAN from a VLAN group:

Device> enable
Device# no vlan group eng-dept vlan-list 10

This example shows that when all the VLANs are cleared from a VLAN group, the VLAN group is cleared:

Device> enable
Device(config)# no vlan group eng-dept vlan-list 30
Vlan 30 is successfully cleared from vlan group eng-dept.
Device(config)# exit
Device# show vlan group group-name eng-dept

This example shows how to clear all the VLAN groups:

Device> enable
Device(config)# no vlan group end-dept vlan-list all
Device(config)# exit
Device# show vlan-group all

Monitoring IEEE 802.1x Port-Based Authentication Statistics and Status

This section list the commands to monitor IEEE 802.1x port-based authentication statistics and status.

Table 4. Privileged EXEC show Commands

Command

Purpose

show dot1x all statistics

Displays 802.1x statistics for all ports

show dot1x interface interface-id statistics

Displays 802.1x statistics for a specific port

show dot1x all [count | details | statistics | summary]

Displays the 802.1x administrative and operational status for a switch

show dot1x interface interface-id

Displays the 802.1x administrative and operational status for a specific port
Table 5. Global Configuration Commands

Command

Purpose

no dot1x logging verbose

Filters verbose 802.1x authentication messages.

Feature History for IEEE 802.1x Port-Based Authentication

Release

Feature

Feature Information

Cisco IOS XE Gibraltar 16.11.1

IEEE 802.1x Port-Based Authentication

IEEE 802.1x authentication prevents unauthorized devices (clients) from gaining access to the network.

Cisco IOS XE Amsterdam 17.2.1

Session Limit - To prevent MAC address flooding DOS attack

The access-session limit profile command was introduced to limit the number of voice and data hosts connecting to a port.

Use Cisco Feature Navigator to find information about platform and software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn.