Catalyst 2960 and 2960-S Switches Software Configuration Guide, Release 15.0(1)SE

Device Roles

Figure 10-1 802.1x Device Roles

• Client —the device (workstation) that requests access to the LAN and switch services and responds to requests from the switch. The workstation must be running 802.1x-compliant client software such as that offered in the Microsoft Windows XP operating system. (The client is the supplicant in the 802.1x standard.)

Note To resolve Windows XP network connectivity and 802.1x authentication issues, read the Microsoft Knowledge Base article:
http://support.microsoft.com/support/kb/articles/Q303/5/97.ASP

• Authentication server —performs the actual authentication of the client. The authentication server validates the identity of the client and notifies the switch whether or not the client is authorized to access the LAN and switch services. Because the switch acts as the proxy, the authentication service is transparent to the client. In this release, the RADIUS security system with Extensible Authentication Protocol (EAP) extensions is the only supported authentication server. It is available in Cisco Secure Access Control Server Version 3.0 or later. RADIUS operates in a client/server model in which secure authentication information is exchanged between the RADIUS server and one or more RADIUS clients.
• Switch (edge switch or wireless access point)—controls the physical access to the network based on the authentication status of the client. The switch acts as an intermediary (proxy) between the client and the authentication server, requesting identity information from the client, verifying that information with the authentication server, and relaying a response to the client. The switch includes the RADIUS client, which is responsible for encapsulating and decapsulating the EAP frames and interacting with the authentication server. (The switch is the authenticator in the 802.1x standard.)

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

The devices that can act as intermediaries include the Catalyst 3750-E, Catalyst 3560-E, Catalyst 3750, Catalyst 3560, Catalyst 3550, Catalyst 2975, Catalyst 2970, Catalyst 2960, Catalyst 2955, Catalyst 2950, Catalyst 2940 switches, or a wireless access point. These devices must be running software that supports the RADIUS client and 802.1x authentication.

Authentication Process

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.

Figure 10-2 Authentication Flowchart

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 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.

We recommend that you specify the attribute value as RADIUS-Request.

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

If Multidomain authentication (MDA) is enabled on a port, this flow can be used with some exceptions that are applicable to voice authorization. For more information on MDA, see the “Multidomain Authentication” section.

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 boot up, 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. For more information, see the “Ports in Authorized and Unauthorized States” section.

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. For more information, see the “Ports in Authorized and Unauthorized States” section.

The specific exchange of EAP frames depends on the authentication method being used. Figure 10-3 shows a message exchange initiated by the client when the client uses the One-Time-Password (OTP) authentication method with a RADIUS server.

Figure 10-3 Message Exchange

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 stops 802.1x authentication.

Figure 10-4 shows the message exchange during MAC authentication bypass.

Figure 10-4 Message Exchange During MAC Authentication Bypass

Authentication Manager

In Cisco IOS Release 12.2(46)SE and earlier, you could not use the same authorization methods, including CLI commands and messages, on this switch and also on other network devices, such as a Catalyst 6000. You had to use separate authentication configurations. Cisco IOS Release 12.2(50)SE and later supports the same authorization methods on all Catalyst switches in a network.

Cisco IOS Release 12.2(55)SE supports filtering verbose system messages from the authentication manager. For details, see the “Authentication Manager CLI Commands” section.

• Port-Based Authentication Methods
• Per-User ACLs and Filter-Ids
• Authentication Manager CLI Commands

Port-Based Authentication Methods

Table 10-1 lists the authentication methods supported in these host modes:

• Single host–Only one data or voice host (client) can be authenticated on a port.
• Multiple host–Multiple data hosts can be authenticated on the same port. (If a port becomes unauthorized in multiple-host mode, the switch denies network access to all of the attached clients.)
• Multidomain authentication (MDA) –Both a data device and voice device can be authenticated on the same switch port. The port is divided into a data domain and a voice domain.
• Multiple authentication–M ultiple hosts can authenticate on the data VLAN. This mode also allows one client on the VLAN if a voice VLAN is configured.

Per-User ACLs and Filter-Ids

In releases earlier than Cisco IOS Release 12.2(50)SE, per-user ACLs and filter Ids were only supported in single-host mode. In Cisco IOS Release 12.2(50), support was added for MDA- and multiauth-enabled ports. In 12.2(52)SE and later, support was added for ports in multihost mode.

In releases earlier than Cisco IOS Release 12.2(50)SE, an ACL configured on the switch is not compatible with an ACL configured on another device running Cisco IOS software, such as a Catalyst 6000 switch.

In Cisco IOS Release 12.2(50)SE or later, the ACLs configured on the switch are compatible with other devices running the Cisco IOS release.

Note You can only set any as the source in the ACL.

Note For any ACL configured for multiple-host mode, the source portion of statement must be any. (For example, permit icmp any host 10.10.1.1.)

You must specify any in the source ports of any defined ACL. Otherwise, the ACL cannot be applied and authorization fails. Single host is the only exception to support backward compatibility.

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.

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 or authentication keyword. For example, the authentication port-control auto interface configuration command enables authentication on an interface. However, the dot1x system-auth-control global configuration command only globally enables or disables 802.1x authentication.

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.

Beginning with Cisco IOS Release 12.2(55)SE, you can filter 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

For more information, see the command reference for this release.

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, CDP, 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.

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 Authentication and Switch Stacks

Note Switch stacks are supported only on Catalyst 2960-S switches running the LAN base image.

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 master is removed from the switch stack. Note that if the stack master fails, a stack member becomes the new stack master by using the election process described in “Managing Switch Stacks,” 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 re-authentication enabled remain in the authenticated state. Communication with the RADIUS server is not required.
• Ports that are already authenticated and that have periodic re-authentication enabled (with the dot1x re-authentication global configuration command) fail the authentication process when the re-authentication occurs. Ports return to the unauthenticated state during the re-authentication 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 stack master and another to a stack member, and if the stack master fails, the switch stack still has connectivity to the RADIUS server.

Note Standalone switches with 64MB of DRAM may encounter system memory exhaustion when 802.1x authentication is enabled concurrently with other features.Hence, it advisable to maintain a baseline free memory of around 1Mb free.

802.1x Host Mode

You can configure an 802.1x port for single-host or for multiple-hosts mode. In single-host mode (see Figure 10-1), 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. Figure 10-5 shows 802.1x port-based authentication in a wireless LAN. 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 (re-authentication 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 10-5 Multiple Host Mode Example

The switch supports multidomain authentication (MDA), which allows both a data device and a voice device, such as an IP Phone (Cisco or non-Cisco), to connect to the same switch port. For more information, see the “Multidomain Authentication” section.

Multidomain Authentication

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

Note To use MDA, the switch must be running the LAN base image.

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:

• To configure a switch port for MDA, see the “Configuring the Host Mode” section.
• You must configure the voice VLAN for the IP phone when the host mode is set to multidomain. For more information, see Chapter13, “Configuring VLANs”
• Voice VLAN assignment on an MDA-enabled port is supported in Cisco IOS Release 12.2(40)SE and later.

Note If you use a dynamic VLAN to assign a voice VLAN on an MDA-enabled switch port on a switch running Cisco IOS Release 12.2(37)SE, the voice device fails authorization.

• 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.
• 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 802.1x authentication. For more information, see the “MAC Authentication Bypass” section.
• 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 changes from single- or multihost to multidomain mode, an authorized data device remains authorized on the port. However, a Cisco IP phone 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-host or multiple-host mode to multidomain mode.
• Switching a port host mode from multidomain to single-host or multiple-hosts mode removes all authorized devices from the port.
• If a data domain is authorized first and placed in the guest VLAN, non-802.1x-capable voice devices need their packets tagged on the voice VLAN to trigger authentication. The phone need not need to send tagged traffic. (The same is true for an 802.1x-capable phone.)
• 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 port voice and data VLANs. You can use only one device on the port to enforce per-user ACLs.

For more information, see the “Configuring the Host Mode” section.

802.1x Multiple Authentication Mode

Multiple-authentication (multiauth) mode allows multiple authenticated clients on the data VLAN. Each host is individually authenticated. If a voice VLAN is configured, this mode also allows one client on the VLAN. (If the port detects any additional voice clients, they are discarded from the port, but no violation errors occur.)

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.

There is no limit to the number of data hosts can authenticate on a multiauthport. However, only one voice device is allowed if the voice VLAN is configured. Since there is no host limit defined violation will not be trigger, if a second voice is seen we silently discard it but do not trigger violation.

For MDA functionality on the voice VLAN, multiple-authentication mode assigns authenticated devices to either a data or a voice VLAN, depending on the VSAs received from the authentication server.

Note When a port is in multiple-authentication mode, the guest VLAN and the authentication-failed VLAN features do not activate.

For more information about critical authentication mode and the critical VLAN, see the “802.1x Authentication with Inaccessible Authentication Bypass” section.

For more information about configuring multiauth mode on a port, see the “Configuring the Host Mode” section.

Beginning with Cisco IOS Release 12.2(55)SE, you can assign a RADIUS-server-supplied VLAN in multi-auth mode, under these conditions:

• The switch is running the LAN base image.
• 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.
• Only one voice VLAN assignment is supported on a multi-auth port.
• 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.
• You cannot configure a guest VLAN or an auth-fail VLAN in multi-auth mode.
• 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.

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 the 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.

For more information see the “Enabling MAC Move” section.

MAC Replace

Note To configure the MAC replace feature, the switch must be running the LAN base image.

Beginning with Cisco IOS Release 12.2(55)SE, 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 multi-domain 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.

For more information see the “Enabling MAC Replace” section.

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.
• Re-authentication successfully occurs.
• Re-authentication 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

Table 10-3 lists the AV pairs and when they are sent are sent by the switch:

You can view the AV pairs that are being sent by the switch by entering the debug radius accounting privileged EXEC command. For more information about this command, see the Cisco IOS Debug Command Reference:
http://www.cisco.com/en/US/docs/ios/12_2/debug/command/reference/122debug.html

For more information about AV pairs, see RFC 3580, “802.1x Remote Authentication Dial In User Service (RADIUS) Usage Guidelines.”

802.1x Readiness Check

Note To use 802.1x readiness check, the switch must be running the LAN base image.

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.

For information on configuring the switch for the 802.1x readiness check, see the “Configuring 802.1x Readiness Check” section.

802.1x Authentication with VLAN Assignment

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.

Voice device authentication is supported with multidomain host mode in Cisco IOS Release 12.2(37)SE. In Cisco IOS Release 12.2(40)SE and later, 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. For more information, see the “Multidomain Authentication” section.

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 malformed VLAN ID, a nonexistent VLAN ID, an RSPAN VLAN, a shut down or suspended VLAN. In the case of a mutlidomain 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 un-authorization 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.

The 802.1x authentication with VLAN assignment feature is not supported on trunk ports, dynamic ports, or with dynamic-access port assignment through a VLAN Membership Policy Server (VMPS).

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, VLAN ID, or VLAN-Group

– [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 802.1x-authenticated user.

For examples of tunnel attributes, see the “Configuring the Switch to Use Vendor-Specific RADIUS Attributes” section.

Using 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. For more information, see Chapter31, “Configuring Network Security with ACLs”

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. Because of limited support of Cisco IOS access lists on the switch, the Filter-Id attribute is supported only for IP ACLs numbered 1 to 199 and 1300 to 2699 (IP standard and 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.

For examples of vendor-specific attributes, see the “Configuring the Switch to Use Vendor-Specific RADIUS Attributes” section. For more information about configuring ACLs, see Chapter31, “Configuring Network Security with ACLs”

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

To configure per-user ACLs, you need to perform these tasks:

• 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.

For more configuration information, see the “Authentication Manager” section.

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.

Note 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.

Beginning with Cisco IOS Release 12.2(55)SE, if there is no static ACL on a port, a dynamic auth-default ACL is created, and policies are enforced before dACLs are downloaded and applied.

Note The auth-default-ACL is created only when the switch is running the LAN base image.

Note The auth-default-ACL does not appear in the running configuration.

The auth-default ACL is created when at least one host with an authorization policy is detected on the port. The auth-default ACL is removed from the port when the last authenticated session ends. You can configure the auth-default ACL by using the ip access-list extended auth-default-acl global configuration command.

Note The auth-default-ACL does not support Cisco Discovery Protocol (CDP) bypass in the single host mode. You must configure a static ACL on the interface to support CDP bypass.

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:

• An auth-default-ACL is created.
• The auth-default-ACL allows only DHCP traffic until policies are enforced.
• 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:

• An auth-default-ACL-OPEN is created and allows all traffic.
• Policies are enforced with IP address insertion to prevent security breaches.
• Web authentication is subject to the auth-default-ACL-OPEN.

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.

If a host falls back to web authentication on a port without a configured ACL:

• If the port is in open authentication mode, the auth-default-ACL-OPEN is created.
• If the port is in closed authentication mode, the auth-default-ACL is created.

The access control entries (ACEs) in the fallback ACL are converted to per-user entries. If the configured fallback profile does not include a fallback ACL, the host is subject to the auth-default-ACL associated with the port.

Note If you use a custom logo with web authentication and it is stored on an external server, the port ACL must allow access to the external server before authentication. You must either configure a static port ACL or change the auth-default-ACL to provide appropriate access to the external server.

Cisco Secure ACS and Attribute-Value Pairs for the Redirect URL

The switch uses these cisco-av-pair VSAs:

• url-redirect is the HTTP to HTTPS URL.
• url-redirect-acl is the switch ACL name or number.

The switch uses the CiscoSecure-Defined-ACL attribute value pair to intercept an HTTP or HTTPS request from the end point device. The switch then forwards the client web browser to the specified redirect address. The url-redirect attribute value pair on the Cisco Secure ACS contains the URL to which the web browser is redirected. The url-redirect-acl attribute value pair contains the name or number of an ACL that specifies the HTTP or HTTPS traffic to redirect. Traffic that matches a permit ACE in the ACL is redirected.

Note Define the URL redirect ACL and the default port ACL on the switch.

If a redirect URL is configured for a client on the authentication server, a default port ACL on the connected client switch port must also be configured.

Cisco Secure ACS and Attribute-Value Pairs for Downloadable ACLs

You can set the CiscoSecure-Defined-ACL Attribute-Value pair on the Cisco Secure ACS with the RADIUS cisco-av-pair vendor-specific attributes (VSAs). This pair specifies the names of the downloadable ACLs on the Cisco Secure ACS with the #ACL#-IP-name-number attribute.

• The name is the ACL name.
• The number is the version number (for example, 3f783768).

If a downloadable ACL is configured for a client on the authentication server, a default port ACL on the connected client switch port must also be configured.

If the default ACL is configured on the switch and the Cisco Secure ACS sends a host-access-policy to the switch, it applies the policy to traffic from the host connected to a switch port. If the policy does not apply, the switch applies the default ACL. If the Cisco Secure ACS sends the switch a downloadable ACL, this ACL takes precedence over the default ACL that is configured on the switch port. However, if the switch receives an host access policy from the Cisco Secure ACS but the default ACL is not configured, the authorization failure is declared.

For configuration details, see the “Authentication Manager” section and the “Configuring 802.1x Authentication with Downloadable ACLs and Redirect URLs” section.

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.

Note This feature is not supported on Cisco ACS Server. (The ACS server ignores the sent VLAN-IDs for new hosts and only authenticates based on the MAC address.)

For configuration information, see the “Configuring VLAN ID-based MAC Authentication” section. Additional configuration is similar MAC authentication bypass, as described in the “Configuring MAC Authentication Bypass” section.

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 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 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 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.

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.

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, or multi-domain modes.

You can configure any active VLAN except an RSPAN VLAN or a voice VLAN as an 802.1x guest VLAN. The guest VLAN feature is not supported on 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 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. For more information, see the “802.1x Authentication with MAC Authentication Bypass” section.

For more information, see the “Configuring a Guest VLAN” section.

802.1x Authentication with Restricted VLAN

You can configure a restricted VLAN (also referred to as an authentication failed VLAN) for each 802.1x port on 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 dow n 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 only on 802.1x ports in single-host mode and on Layer 2 ports.

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

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

For more information, see the “Configuring a Restricted VLAN” section.

802.1x Authentication with Inaccessible Authentication Bypass

The Inaccessible Authentication Bypass feature (formally known as Critical-Auth) provides the ability to configure an 802.1X or MAB authenticated switch port to furnish connected hosts with special network access in the event that the RADIUS servers are unavailable to provide authentication. You configure a particular access VLAN for this critical access (known as the Critical VLAN) and optionally configure the port to reinitialize authentication when a RADIUS servers becomes available.

The Inaccessible Authentication Bypass feature is triggered under either of these conditions:

• All configured RADIUS servers enter the dead state during an authentication attempt
• A port with Inaccessible Authentication Bypass comes up while all configured RADIUS servers are in the dead state

In either case, the switch immediately assigns the host attempting to authenticate on the port to the configured Critical VLAN. Hosts with established authentication sessions are not affected.

By default, any host that has been authenticated through Inaccessible Authentication Bypass remains in the Critical VLAN until the link goes down. If the authentication event server alive action reinitialize command has been configured on the port, then all authentication sessions on the port will be reauthenticated as soon as one of the configured RADIUS servers transitions into the up state.

To enable Inaccessible Authentication Bypass on a switch port, use the authentication event server dead action authorize vlan vlan-id interface configuration command.

To enable reauthentication when the RADIUS servers become available, use the authentication event server alive action reinitialize interface configuration command.

For more detailed configuration information, see the “Configuring Inaccessible Authentication Bypass and Critical Voice VLAN” section.

Overview of Authentication Results

The behavior of the Inaccessible Authentication Bypass feature varies depending on the authorization state of the switch port and RADIUS servers when the feature is triggered:

• If the port is unauthorized and the RADIUS servers are unavailable when a host attempts to authenticate, the switch places the port in the critical-authentication state, authorized in the configured Critical VLAN.
• If the port is attempting an authentication and the RADIUS servers become unavailable during the exchange, the exchange times out and the switch places the port in the critical-authentication state, authorized in the configured Critical VLAN during the next authentication attempt.
• If the port is already authorized and all of the RADIUS servers become unavailable, then the Inaccessible Authentication Bypass feature is triggered during the next reauthentication attempt. At that time, if the RADIUS servers are still unavailable, the switch moves the port into the critical-authentication state, suspends the reauthentication timers, and begins ignoring any EAPOL-Start messages on the switch port. Any VLAN assignments made during the previously successful authorizations are retained.

Single-Host Mode Port Behavior

On a single-host mode switch port, the Inaccessible Authentication Bypass feature operates as described in “Overview of Authentication Results” for a single host. As expected on a single-host mode port, if more than a single host is detected on the switch port, then the switch port enters an err-disable state.

Multi-Host Mode Port Behavior

On a multi-host mode switch port, the Inaccessible Authentication Bypass feature operates as described in “Overview of Authentication Results” for the first host authenticated or authentication attempt on the switch port. As expected in multi-host mode, subsequent hosts are granted access to whatever VLAN the port is currently authorized in: either the previously assigned VLAN from a successful authorization or the Critical VLAN if the port was authenticated using the Inaccessible Authentication Bypass feature.

Multi-Domain Mode Port Behavior

On a multi-domain mode (MDA) switch port, the Inaccessible Authentication Bypass feature operates as described in “Overview of Authentication Results” for a single host in the data domain. As expected on a multi-domain port, if another device attempts to authenticate in the data domain, the port enters an err-disable state due to security violation. The introduction of a voice domain device can have unintuitive consequences for an MDA mode port with Inaccessible Authentication Bypass enabled.

Assuming the RADIUS servers are unavailable:

• If both the data domain and voice domain are already authenticated and authorized in their respective VLANs, each domain retains its authorized VLAN during its next reauthentication attempt. The switch places the port into critical-authentication state, suspends the reauthentication timer and begins ignoring EAPOL-Start messages in the domain reauthenticating.
• If the voice domain is authenticated and the data domain is not, a reauthentication attempt in the voice domain causes the port to move into critical-authentication state, suspends the reauthentication timer in the voice domain, and causes the voice domain to begin ignoring EAPOL-Start messages. The voice domain continues to operate, retaining its authorized Voice VLAN.
• If the voice domain is authenticated and the data domain is not, an authentication attempt in the data domain causes the port to move into critical-authentication state and causes the data domain to authorize in the configured Critical VLAN. The voice domain continues to operate, retaining its authorized Voice VLAN.
• If the data domain is authenticated and the voice domain is not, a reauthentication attempt in the data domain causes the port to move into a critical-authentication state, suspends the reauthentication timer in the data domain, and causes the data domain to begin ignoring EAPOL-Start messages. The data domain continues to operate, retaining its authorized Data VLAN.
• If the data domain is authenticated and voice domain is not, and a voice device attempts to authenticate, the switch is unable to classify the device as a voice domain device (normally accomplished with the device-traffic-class = voice RADIUS attribute) and attempts to authenticate the device in the data domain. This action immediately results in a security violation because more than one device is detected in the data domain and the port enters an err-disable state.
• If neither domain is authenticated, the first authentication attempt by any device causes the port to move into a critical-authentication state, and authorizes the data domain in the Critical VLAN. If the device is a phone, it may not work properly in the Critical VLAN. Any other device attempting to authenticate is subsequently assigned to the data domain and immediately triggers a security violation, which places the port in an err-disable state.

Support on Multiple-Authentication Ports

To enable Inaccessible Authentication Bypass on ports configured with host mode multi-auth, you must use the authentication event server dead action reinitialize vlan vlan-id command.

In contrast to the authentication event server dead action authorize vlan vlan-id command, which leaves existing authentication sessions established, the reinitialize command causes all existing data domain sessions to immediately reauthenticate, placing them into the configured Critical VLAN. This reinitialization is triggered whenever the next new authentication attempt is made on the port while the RADIUS servers are unavailable. After the port has been reinitialized, any new hosts attempting to connect to the port are moved to the data domain and authorized on the Critical VLAN. The port is placed in a critical-authentication state.

During a reinitialization event, an authenticated voice domain device is not reinitialized. This device retains its authorized Voice VLAN.

Note If a port is configured with host mode multi-auth, the authentication event server dead action authorize vlan vlan-id command has no effect on the interface’s behavior in the event that the RADIUS server becomes unavailable.

Inaccessible Authentication Bypass Feature Interactions

Guest VLAN

Inaccessible Authentication Bypass is compatible with the Guest VLAN feature. When a device is authorized using the Guest VLAN feature and Inaccessible Authentication Bypass is triggered, the port enters the critical-authentication state, and the previously authorized Guest VLAN assignment is retained.

Restricted VLAN

Inaccessible Authentication Bypass is compatible with the Restricted VLAN feature. When a device is authorized using the Restricted VLAN feature and Inaccessible Authentication Bypass is triggered, the port enters the critical-authentication state, and the previously authorized Restricted VLAN assignment is retained.

Private VLAN

Inaccessible Authentication Bypass is compatible with the Private VLAN feature. However, the configured Critical VLAN must be a secondary private VLAN.

Switch Stack

The stack master switch checks the status of the RADIUS servers by periodically sending keepalive packets. When the stack master switch detects a change in the status of one of the configured RADIUS servers, it sends a notification to each stack member switch. This allows the stack members to check the status of RADIUS servers when reauthenticating switch ports with Inaccessible Authentication Bypass enabled. If a new member switch is added to the stack, the stack master switch sends the member the RADIUS server statuses.

If the new stack master switch is elected, the link between the switch stack and RADIUS server might change. Consequently, the new stack master switch immediately sends keepalive packets to update the status of every RADIUS server.

If a RADIUS server status changes from dead to up, all of the stack switches reauthenticate all switch ports currently in the critical-authentication state.

802.1x Critical Voice VLAN

When an IP phone connected to a port is authenticated by the access control server (ACS), the phone is put into the voice domain. If the ACS 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.

With this release, you can enter the authentication event server dead action authorize voic e interface configuration command to configure the critical voice VLAN feature. When the ACS 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 CDP (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.

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 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 CDP message from the IP phone. Cisco IP phones do not relay CDP 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 802.1x authentication is enabled on a voice VLAN port, the switch drops packets from unrecognized IP phones more than one hop away.

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

For more information about voice VLANs, see Chapter15, “Configuring Voice VLAN”

802.1x Authentication with Port Security

In general, Cisco does not recommend enabling port security when IEEE 802.1x is enabled. Since IEEE 802.1x enforces a single MAC address per port (or per VLAN when MDA is configured for IP telephony), port security is redundant and in some cases may interfere with expected IEEE 802.1x operations.

802.1x Authentication with Wake-on-LAN

The 802.1x authentication with the wake-on-LAN (WoL) feature allows dormant PCs to be powered when the switch receives a specific Ethernet frame, known as the magic packet. You can use this feature in environments where administrators need to connect to systems that have been powered down.

When a host that uses WoL is attached through an 802.1x port and the host powers off, the 802.1x port becomes unauthorized. The port can only receive and send EAPOL packets, and WoL magic packets cannot reach the host. When the PC is powered off, it is not authorized, and the switch port is not opened.

When the switch uses 802.1x authentication with WoL, the switch forwards traffic to unauthorized 802.1x ports, including magic packets. While the port is unauthorized, the switch continues to block ingress traffic other than EAPOL packets. The host can receive packets but cannot send packets to other devices in the network.

Note If PortFast is not enabled on the port, the port is forced to the bidirectional state.

When you configure a port as unidirectional by using the authentication control-direction in interface configuration command, the port changes to the spanning-tree forwarding state. The port can send packets to the host but cannot receive packets from the host.

When you configure a port as bidirectional by using the authentication control-direction both interface configuration command, the port is access-controlled in both directions. The port does not receive packets from or send packets to the host.

802.1x Authentication with MAC Authentication Bypass

You can configure the switch to authorize clients based on the client MAC address (see Figure 10-2) by using the MAC authentication bypass feature. For example, you can enable this feature on 802.1x ports connected to devices such as printers.

If 802.1x authentication times out while waiting for an EAPOL response from the client, the switch tries to authorize the client by using MAC authentication bypass.

When the MAC authentication bypass feature is enabled on an 802.1x port, the switch uses the MAC address as the client identity. The authentication server has a database of client MAC addresses that are allowed network access. After detecting a client on an 802.1x port, the switch waits for an Ethernet packet from the client. The switch sends the authentication server a RADIUS-access/request frame with a username and password based on the MAC address. If authorization succeeds, the switch grants the client access to the network. If authorization fails, the switch assigns the port to the guest VLAN if one is configured.

If an EAPOL packet is detected on the interface during the lifetime of the link, the switch determines that the device connected to that interface is an 802.1x-capable supplicant and uses 802.1x authentication (not MAC authentication bypass) to authorize the interface. EAPOL history is cleared if the interface link status goes down.

If the switch already authorized a port by using MAC authentication bypass and detects an 802.1x supplicant, the switch does not unauthorize the client connected to the port. When re-authentication occurs, the switch uses 802.1x authentication as the preferred re-authentication process if the previous session ended because the Termination-Action RADIUS attribute value is DEFAULT.

Clients that were authorized with MAC authentication bypass can be re-authenticated. The re-authentication process is the same as that for clients that were authenticated with 802.1x. During re-authentication, the port remains in the previously assigned VLAN. If re-authentication is successful, the switch keeps the port in the same VLAN. If re-authentication fails, the switch assigns the port to the guest VLAN, if one is configured.

If re-authentication is based on the Session-Timeout RADIUS attribute (Attribute[27]) and the Termination-Action RADIUS attribute (Attribute [29]) and if the Termination-Action RADIUS attribute (Attribute [29]) action is Initialize, (the attribute value is DEFAULT), the MAC authentication bypass session ends, and connectivity is lost during re-authentication. If MAC authentication bypass is enabled and the 802.1x authentication times out, the switch uses the MAC authentication bypass feature to initiate re-authorization. For more information about these AV pairs, see RFC 3580, “802.1X Remote Authentication Dial In User Service (RADIUS) Usage Guidelines.”

MAC authentication bypass interacts with the features:

• 802.1x authentication—You can enable MAC authentication bypass only if 802.1x authentication is enabled on the port.
• Guest VLAN—If a client has an invalid MAC address identity, the switch assigns the client to a guest VLAN if one is configured.
• Restricted VLAN—This feature is not supported when the client connected to an 802.lx port is authenticated with MAC authentication bypass.
• Port security—See the “802.1x Authentication with Port Security” section.
• Voice VLAN—See the “802.1x Authentication with Voice VLAN Ports” section.
• VLAN Membership Policy Server (VMPS)—802.1x and VMPS are mutually exclusive.
• 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 cannot enable NEAT when MAB is enabled on an interface.

For more configuration information, see the “Authentication Manager” section.

Cisco IOS Release 12.2(55)SE and later supports filtering of verbose MAB system messages. See the “Authentication Manager CLI Commands” section.

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.

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.

For more information, see the “Configuring 802.1x User Distribution” section.

Network Admission Control Layer 2 802.1x Validation

Note To use Network Admission Control, the switch must be running the LAN base image.

The switch supports the Network Admission Control (NAC) Layer 2 802.1x validation, which checks the antivirus condition or posture of endpoint systems or clients before granting the devices network access. With NAC Layer 2 802.1x 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 or show dot1x privileged EXEC command.
• Configure secondary private VLANs as guest VLANs.

Configuring NAC Layer 2 802.1x validation is similar to configuring 802.1x port-based authentication except that you must configure a posture token on the RADIUS server. For information about configuring NAC Layer 2 802.1x validation, see the “Configuring NAC Layer 2 802.1x Validation” section and the “Configuring Periodic Re-Authentication” section.

For more information about NAC, see the Network Admission Control Software Configuration Guide.

For more configuration information, see the “Authentication Manager” section.

Flexible Authentication Ordering

You can use flexible authentication ordering to configure the order of methods that a port uses to authenticate a new host. 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. For more information see the “Configuring Flexible Authentication Ordering” section.

Open1x Authentication

Open1x authentication allows a device to access 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.

For more information see the “Configuring the Host Mode” section.

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.

Using 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. When an attempt to authenticate the data client caused a security violation in previous releases, the entire port shut down, resulting in a complete loss of connectivity.

You can use this feature where a PC is connected to the IP phone. A security violation found on the data VLAN shuts down only the data VLAN. The traffic on the voice VLAN continues without interruption.

For information on configuring voice aware 802.1x security, see the “Configuring Voice Aware 802.1x Security” section.

802.1x Supplicant and Authenticator Switches with Network Edge Access Topology (NEAT)

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.

• 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. Beginning with Cisco IOS Release 15.0(1)SE, 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 do t1x 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 transient command on a supplicant switch when BPDU guard is enabled on the authenticator switch port with the spanning-tree bpduguard enable interface onfiguration 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.

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, as shown in Figure 10-6.
• 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 ACS. (You can configure this under the group or the user settings.)

Figure 10-6 Authenticator and Supplicant Switch using CISP

Guidelines

• You can configure NEAT ports with the same configurations as the other authentication ports. When the supplicant switch authenticates, the port mode is changed from access to trunk based on the switch vendor-specific attributes (VSAs). (device-traffic-class=switch).
• The VSA changes the authenticator switch port mode from access to trunk and enables 802.1x trunk encapsulation and the access VLAN if any would be converted to a native trunk VLAN. VSA does not change any of the port configurations on the supplicant
• To change the host mode and the apply a standard port configuration on the authenticator switch port, you can also use Auto Smartports user-defined macros, instead of the switch VSA. This allows you to remove unsupported configurations on the authenticator switch port and to change the port mode from access to trunk. For information, see the AutoSmartports Configuration Guide.

For more information, see the “Configuring an Authenticator and a Supplicant Switch with NEAT” section.

Using IEEE 802.1x Authentication with ACLs and the RADIUS Filter-Id Attribute

Note To use IEEE 802.1x authentication with ACLs and the Filter-Id attribute, the switch must be running the LAN base image.

The switch supports both IP standard and IP extended port access control lists (ACLs) applied to ingress ports.

• ACLs that you configure
• ACLs from the Access Control Server (ACS)

An IEEE 802.1x port in single-host mode uses ACLs from the ACS to provide different levels of service to an IEEE 802.1x-authenticated user. When the RADIUS server authenticates this type of user and port, it sends ACL attributes based on the user identity to the switch. The switch applies the attributes to the port for the duration of the user session. If the session is over, authentication fails, or a link fails, the port becomes unauthorized, and the switch removes the ACL from the port.

Only IP standard and IP extended port ACLs from the ACS support the Filter-Id attribute. It specifies the name or number of an ACL. The Filter-id attribute can also specify the direction (inbound or outbound) and a user or a group to which the user belongs.

• The Filter-Id attribute for the user takes precedence over that for the group.
• If a Filter-Id attribute from the ACS specifies an ACL that is already configure, it takes precedence over a user-configured ACL.
• If the RADIUS server sends more than one Filter-Id attribute, only the last attribute is applied.

If the Filter-Id attribute is not defined on the switch, authentication fails, and the port returns to the unauthorized state.

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:

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

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.

Default 802.1x Authentication Configuration

802.1x Authentication Configuration Guidelines

• 802.1x Authentication
• VLAN Assignment, Guest VLAN, Restricted VLAN, and Inaccessible Authentication Bypass
• MAC Authentication Bypass
• Maximum Number of Allowed Devices Per Port

802.1x Authentication

• When IEEE 802.1x authentication is enabled, ports are authenticated before any other Layer 2 feature is 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 IEEE 802.1x protocol is supported on Layer 2 static-access ports and voice VLAN ports, but it is not supported on these port types:

– Dynamic-access ports—If you try to enable 802.1x authentication on a dynamic-access (VLAN Query Protocol [VQP]) port, an error message appears, and 802.1x authentication is not enabled. If you try to change an 802.1x-enabled port to dynamic VLAN assignment, an error message appears, and the VLAN configuration 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.
• Cisco IOS Release 12.2(55)SE and later supports filtering of system messages related to 802.1x authentication. See the “Authentication Manager CLI Commands” section.

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.
• The 802.1x authentication with VLAN assignment feature is not supported on trunk ports, dynamic ports, or with dynamic-access port assignment through a VMPS.
• 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 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 trunk ports; it is supported only on access ports.

MAC Authentication Bypass

• Unless otherwise stated, the MAC authentication bypass guidelines are the same as the 802.1x authentication guidelines. For more information, see the “802.1x Authentication” section.
• 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.

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 multiple-host 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.

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 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.

Beginning in privileged EXEC mode, follow these steps to enable the 802.1x readiness check on the switch:

This example shows how to enable a readiness check on a switch to query a port. It also shows the response received from the queried port verifying that the device connected to it is 802.1x-capable:

Configuring 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 on the switch 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 switch without interruption.

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

• 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 switch.

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.

Beginning in privileged EXEC mode, follow these steps to enable voice aware 802.1x security:

This example shows how to configure the switch to shut down any VLAN on which a security violation error occurs:

This example shows how to re-enable all VLANs that were error disabled on port Gigabit Ethernet 40/2.

You can verify your settings by entering the show errdisable detect privileged EXEC command.

Configuring 802.1x Violation Modes

Note To configure violation modes, the switch must be running the LAN base image.

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:

Configuring 802.1x Authentication

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.

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

This is the 802.1x AAA process:

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.

Beginning in privileged EXEC mode, follow these steps to configure 802.1x port-based authentication:

Configuring the 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 the 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 in which they were configured.

Beginning in privileged EXEC mode, follow these steps to configure the RADIUS server parameters on the switch. This procedure is required.

To clear the specified RADIUS server, use the no radius-server host { hostname | ip-address } global configuration command.

This example shows how to specify the server with IP address 172.20.39.46 as the RADIUS server, to use port 1612 as the authorization port, and to set the encryption key to rad123, matching the key on the RADIUS server:

You can globally configure the timeout, retransmission, and encryption key values for all RADIUS servers by using the radius-server host global configuration command. If you want to configure these options on a per-server basis, use the radius-server timeout, radius-server retransmit and the radius-server key global configuration commands. For more information, see the “Configuring Settings for All RADIUS Servers” section.

You also need to configure some settings on the RADIUS server. These settings include the IP address of the switch and the key string to be shared by both the server and the switch. For more information, see the RADIUS server documentation.

Configuring the Host Mode

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

This procedure is optional.

To disable multiple hosts on the port, use the no authentication host-mode interface configuration command.

This example shows how to enable 802.1x authentication and to allow multiple hosts:

This example shows how to enable MDA and to allow both a host and a voice device on the port:

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.

Beginning in privileged EXEC mode, 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.

To disable periodic re-authentication, use the no authentication periodic interface configuration command. To return to the default number of seconds between re-authentication attempts, use the no authentication timer interface configuration command.

This example shows how to enable periodic re-authentication and set the number of seconds between re-authentication attempts to 4000:

Manually Re-Authenticating a Client Connected to a Port

You can manually re-authenticate the client connected to a specific port at any time by entering the dot1x re-authenticate interface interface-id privileged EXEC command. This step is optional. If you want to enable or disable periodic re-authentication, see the “Configuring Periodic Re-Authentication” section.

This example shows how to manually re-authenticate the client connected to a port:

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 inactivity interface configuration command controls the idle period. A failed client authentication 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.

To return to the default quiet time, use the no authentication timer inactivity interface configuration command.

This example shows how to set the quiet time on the switch to 30 seconds:

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.

To return to the default retransmission time, use the no authentication timer reauthenticate interface configuration command.

This example shows how to set 60 as the number of seconds that the switch waits for a response to an EAP-request/identity frame from the client before resending the request:

Setting the Switch-to-Client Frame-Retransmission Number

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.

To return to the default retransmission number, use the no dot1x max-req interface configuration command.

This example shows how to set 5 as the number of times that the switch sends an EAP-request/identity request before restarting the authentication process:

Setting the Re-Authentication Number

You can also change the number of times that the switch 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.

To return to the default re-authentication number, use the no dot1x max-reauth-req interface configuration command.

This example shows how to set 4 as the number of times that the switch restarts the authentication process before the port changes to the unauthorized state:

Enabling MAC Move

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

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

This example shows how to globally enable MAC move on a switch:

Enabling MAC Replace

Note To enable MAC replace, the switch must be running the LAN base image.

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.

This example shows how to enable MAC replace on an interface:

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.

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:

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

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.

Use the show radius statistics privileged EXEC command to display the number of RADIUS messages that do not receive the accounting response message.

This example shows how to configure 802.1x accounting. The first command configures the RADIUS server, specifying 1813 as the UDP port for accounting:

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.

To disable and remove the guest VLAN, use the no authentication event no-response action authorize vlan vlan-id interface configuration command. The port returns to the unauthorized state.

This example shows how to enable VLAN 2 as an 802.1x guest VLAN:

This example shows how to set 3 as the quiet time on the switch, to set 15 as the number of seconds that the switch waits for a response to an EAP-request/identity frame from the client before re-sending the request, and to enable VLAN 2 as an 802.1x guest VLAN when an 802.1x port is connected to a DHCP client:

Configuring a Restricted VLAN

When you configure a restricted VLAN on a switch stack or a switch, clients that are 802.1x-compliant are moved into the restricted VLAN when the authentication server does not receive a valid username and password. The switch 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.

To disable and remove the restricted VLAN, use the no authentication event fail action authorize vlan-id interface configuration command. The port returns to the unauthorized state.

This example shows how to enable VLAN 2 as an 802.1x 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 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.

To return to the default value, use the no authentication event retry interface configuration command.

This example shows how to set 2 as the number of authentication attempts allowed before the port moves to the restricted VLAN:

Configuring Inaccessible Authentication Bypass and Critical Voice VLAN

You can configure the inaccessible bypass feature, also referred to as critical authentication or the AAA fail policy to allow data traffic to pass through on the native VLAN when the server is not available. You can also configure the critical voice VLAN feature so that if the server is not available and traffic from the host is tagged with the voice VLAN, the connected device (the phone) is put in the configured voice VLAN for the port.

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

This example shows how to configure the inaccessible authentication bypass feature and configure the critical voice VLAN:

Configuring 802.1x Authentication with Wake-on-LAN

Beginning in privileged EXEC mode, follow these steps to enable 802.1x authentication with WoL. This procedure is optional.

To disable 802.1x authentication with WoL, use the no authentication control-direction interface configuration command.

These examples show how to enable 802.1x authentication with WoL and set the port as bidirectional:

Configuring MAC Authentication Bypass

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

To disable MAC authentication bypass, use the no authentication order interface configuration command.

This example shows how to enable MAC authentication bypass:

Configuring 802.1x User Distribution

Beginning in global configuration, follow these steps to configure a VLAN group and to map a VLAN to it:

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

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

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

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

This example shows how to clear all the VLAN groups:

For more information about these commands, see the Cisco IOS Security Command Reference.

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.

This example shows how to configure NAC Layer 2 802.1x validation:

Configuring an Authenticator and a Supplicant 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.

For overview information, see the “802.1x Supplicant and Authenticator Switches with Network Edge Access Topology (NEAT)” section.

Note The cisco-av-pairs must be configured as device-traffic-class=switch on the ACS, 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:

This example shows how to configure a switch as an 802.1x authenticator:

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

This example shows how to configure a switch as a supplicant:

Switch(config-if)# dot1x pae supplicant
Switch(config-if)# dot1x credentials test
Switch(config-if)# end

Configuring NEAT with Auto Smartports Macros

You can also use an Auto Smartports user-defined macro instead of the switch VSA to configure the authenticator switch. For information, see the Auto Smartports Configuration Guide.

Configuring 802.1x Authentication with Downloadable ACLs and Redirect URLs

In addition to configuring 802.1x authentication on the switch, you need to configure the ACS. For more information, see the Cisco Secure ACS configuration guides.

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.

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:

Configuring a Downloadable Policy

Beginning in privileged EXEC mode:

This example shows how to configure a switch for a downloadable policy:

Configuring VLAN ID-based MAC Authentication

Beginning in privileged EXEC mode, follow these steps:

There is no show command to confirm the status of VLAN ID-based MAC authentication. You can use the debug radius accounting privileged EXEC command to confirm the RADIUS attribute 32. For more information about this command, see the Cisco IOS Debug Command Reference :
http://www.cisco.com/en/US/docs/ios/debug/command/reference/db_q1.html#wp1123741

This example shows how to globally enable VLAN ID-based MAC authentication on a switch:

Configuring Flexible Authentication Ordering

Beginning in privileged EXEC mode, follow these steps:

This example shows how to configure a port attempt 802.1x authentication first, followed by web authentication as fallback method:

Configuring Open1x

Beginning in privileged EXEC mode:

This example shows how to configure open 1x on a port:

Disabling 802.1x Authentication on the 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.

To configure the port as an 802.1x port access entity (PAE) authenticator, which enables 802.1x on the port but does not allow clients connected to the port to be authorized, use the dot1x pae authenticator interface configuration command.

This example shows how to disable 802.1x authentication on the port:

Resetting the 802.1x Authentication Configuration to the 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.