Cisco Industrial Ethernet 4000, 4010 and 5000 Switch Software. Configuration Guide (2022)

Configuring Switch-Based Authentication

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187

Configuring IEEE 802.1x Port-Based

Authentication

Restrictions for Configuring IEEE 802.1x Port-Based

Authentication

To use this feature, the switch must be running the LAN Base image.

Information About Configuring IEEE 802.1x Port-Based

Authentication

IEEE 802.1x Port-Based Authentication

The standard defines a client-server-based access control and authentication protocol to prevent unauthorized clients

from connecting to a LAN through publicly accessible ports. The authentication server authenticates each client

connected to a switch port before making available any switch or LAN services.

Until the client is authenticated, IEEE 802.1x access control allows only Extensible Authentication Protocol over LAN

(EAPOL), Cisco Discovery Protocol (CDP), and Spanning Tree Protocol (STP) traffic through the port to which the client

is connected. After authentication, normal traffic passes through the port.

Device Roles

Figure 18

802.1x Device Roles

Authentication

server

(RADIUS)

Workstations

(clients)

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.)

189

Configuring IEEE 802.1x Port-Based Authentication

Information About Configuring IEEE 802.1x Port-Based Authentication

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 (switches, or a wireless access point) 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.

190

Configuring IEEE 802.1x Port-Based Authentication

Information About Configuring IEEE 802.1x Port-Based Authentication

Figure

Authentication Flowchart

Start

Is the client IEEE

IEEE 802.1x authentication

Is MAC authentication

802.1x capable?

process times out.

bypass enabled? 1

Yes

The switch gets an

EAPOL message,

User does not have a

and the EAPOL

certificate but the system

message

previously logged on to

Start IEEE 802.1x port-based

exchange begins.

Use MAC authentication

the network using

authentication.

bypass.1

a computer certificate.

Client

Client MAC

identity is

address

invalid

valid

identity

is invalid.

is valid.

Assign the port to

a guest VLAN.

a restricted VLAN.

a VLAN.

a guest VLAN.1

Done

All authentication

servers are down.

Use inaccessible

authentication bypass

(critical authentication)

to assign the critical

1 = This occurs if the switch does not

port to a VLAN.

detect EAPOL packets from the client.

Done

The switch reauthenticates a client when one of these situations occurs:

Periodic reauthentication is enabled, and the reauthentication timer expires.

You can configure the reauthentication 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 reauthentication occurs.

The Termination-Action RADIUS attribute (Attribute [29]) specifies the action to take during reauthentication. 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 reauthentication. When the ReAuthenticate action is set (the attribute

value is RADIUS-Request), the session is not affected during reauthentication.

You manually reauthenticate 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 Multidomain Authentication, page 197.

191

Configuring IEEE 802.1x Port-Based Authentication

Information About Configuring IEEE 802.1x Port-Based Authentication

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 failover backup to the first one. The RADIUS host entries are tried in the order

in which they were configured.

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 Ports in Authorized and

Unauthorized States, page 195.

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 Ports in Authorized and

Unauthorized States, page 195.

The specific exchange of EAP frames depends on the authentication method being used. Figure 20 on page 193 shows

a message exchange initiated by the client when the client uses the One-Time-Password (OTP) authentication method

with a RADIUS server.

192

Configuring IEEE 802.1x Port-Based Authentication

Information About Configuring IEEE 802.1x Port-Based Authentication

Figure 20

Message Exchange

Authentication

server

Client

(RADIUS)

EAPOL-Start

EAP-Request/Identity

EAP-Response/Identity

RADIUS Access-Request

EAP-Request/OTP

RADIUS Access-Challenge

EAP-Response/OTP

RADIUS Access-Request

EAP-Success

RADIUS Access-Accept

Port Authorized

EAPOL-Logoff

Port Unauthorized

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 21

Message Exchange During MAC Authentication Bypass

Authentication

server

Client

Switch

(RADIUS)

EAPOL Request/Identity

Ethernet packet

RADIUS Access/Request

RADIUS Access/Accept

193

Configuring IEEE 802.1x Port-Based Authentication

Information About Configuring IEEE 802.1x Port-Based Authentication

Authentication Manager

Port-Based Authentication Methods

Table 29 on page 194 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—Multiple hosts can authenticate on the data VLAN. This mode also allows one client on the

VLAN if a voice VLAN is configured.

Table 29

802.1x Features

Authentication Method

Mode

Single Host

Multiple Host

MDA¹

Multiple

Authentication²

802.1x

VLAN assignment

Per-user ACL

Filter-Id attribute

Filter-ID attribute

Filter-Id attribute

Downloadable ACL

Redirect URL

MAC authentication bypass

VLAN assignment

Per-user ACL

Filter-Id attribute

Filter-ID attribute

Filter-Id attribute

Downloadable ACL

Redirect URL

Standalone web authentication

Proxy ACL, Filter-Id attribute, downloadable ACL²

NAC Layer 2 IP validation

Filter-Id attribute

Filter-Id attribute³

Downloadable ACL

Redirect URL

Web authentication as fallback

Proxy ACL

Proxy ACL³

method³

Filter-Id attribute

Downloadable ACL

1. MDA = Multidomain authentication.

2. Also referred to as multiauth.

3. For clients that do not support 802.1x authentication.

194

Configuring IEEE 802.1x Port-Based Authentication

Information About Configuring IEEE 802.1x Port-Based Authentication

Per-User ACLs and Filter-Ids

Support was added for MDA- and multiauth-enabled ports. In 12.2(52)SE and later, support was added for ports in

multihost mode.

An ACL configured on the switch is not compatible with an ACL configured on another device running Cisco IOS

software, such as a Catalyst 6500 switch.

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 multihost 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-authentication 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.

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

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

195

Configuring IEEE 802.1x Port-Based Authentication

Information About Configuring IEEE 802.1x Port-Based Authentication

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 Host Mode

You can configure an 802.1x port for single-host or for multiple-hosts mode. In single-host mode (see Figure 18 on

page 189), 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 22 on page 197 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 (reauthentication fails or an EAPOL-logoff

message is received), the switch denies network access to all of the attached clients. In this topology, the wireless

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

196

Configuring IEEE 802.1x Port-Based Authentication

Information About Configuring IEEE 802.1x Port-Based Authentication

Figure 22

Multiple Host Mode Example

Authentication

server

(RADIUS)

Workstations

(clients)

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 Multidomain

Authentication, page 197.

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.

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 Configuring the Host Mode, page 222.

You must configure the voice VLAN for the IP phone when the host mode is set to multidomain. For more information,

see Configuring VLANs, page 289

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 MAC Authentication Bypass Guidelines,

page 217.

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.

197

Configuring IEEE 802.1x Port-Based Authentication

Information About Configuring IEEE 802.1x Port-Based Authentication

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 Configuring the Host Mode, page 222.

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 802.1x Authentication with

Inaccessible Authentication Bypass, page 207.

For more information about configuring multiauth mode on a port, see Configuring the Host Mode, page 222.

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.

198

Configuring IEEE 802.1x Port-Based Authentication

Information About Configuring IEEE 802.1x Port-Based Authentication

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 Configuring Optional 802.1x Authentication Features, page 224.

MAC Replace

The MAC replace feature can be configured to address the violation that occurs when a host attempts to connect to a

port where another host was previously authenticated.

Note: This feature does not apply to ports in multiauth mode, because violations are not triggered in that mode. It does

not apply to ports in multiple host mode, because in that mode, only the first host requires authentication.

If you configure the authentication violation interface configuration command with the replace keyword, the

authentication process on a port in multidomain mode is:

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

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

address.

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

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

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

For more information see Configuring Optional 802.1x Authentication Features, page 224.

802.1x Accounting

The 802.1x standard defines how users are authorized and authenticated for network access but does not keep track of

network usage. 802.1x accounting is disabled by default. You can enable 802.1x accounting to monitor this activity on

802.1x-enabled ports:

User successfully authenticates.

User logs off.

Link-down occurs.

Reauthentication successfully occurs.

Reauthentication fails.

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

must be configured to log accounting messages.

199

Configuring IEEE 802.1x Port-Based Authentication

Information About Configuring IEEE 802.1x Port-Based Authentication

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

Attribute Number

AV Pair Name

START

INTERIM

STOP

Attribute[1]

User-Name

Always

Attribute[4]

NAS-IP-Address

Always

Attribute[5]

NAS-Port

Always

Attribute[8]

Framed-IP-Address

Never

Sometimes¹

Attribute[25]

Class

Always

Attribute[30]

Called-Station-ID

Always

Attribute[31]

Calling-Station-ID

Always

Attribute[40]

Acct-Status-Type

Always

Attribute[41]

Acct-Delay-Time

Always

Attribute[42]

Acct-Input-Octets

Never

Always

Attribute[43]

Acct-Output-Octets

Never

Always

Attribute[44]

Acct-Session-ID

Always

Attribute[45]

Acct-Authentic

Always

Attribute[46]

Acct-Session-Time

Never

Always

Attribute[49]

Acct-Terminate-Cause

Never

Always

Attribute[61]

NAS-Port-Type

Always

1. The Framed-IP-Address AV pair is sent only if a valid Dynamic Host Control Protocol (DHCP) binding exists for the

host in the DHCP snooping bindings table.

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 AV pairs, see RFC 3580, “802.1x Remote Authentication Dial In User Service (RADIUS)

Usage Guidelines.”

802.1x Readiness Check

The 802.1x readiness check monitors 802.1x activity on all the switch ports and displays information about the devices

connected to the ports that support 802.1x. You can use this feature to determine if the devices connected to the switch

ports are 802.1x-capable. You use an alternate authentication such as MAC authentication bypass or web authentication

for the devices that do not support 802.1x functionality.

This feature only works if the supplicant on the client supports a query with the NOTIFY EAP notification packet. The client

must respond within the 802.1x timeout value.

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Information About Configuring IEEE 802.1x Port-Based Authentication

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.

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.

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.

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

page 220.

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.

When a voice device is authorized and the RADIUS server returns 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 Multidomain

Authentication, page 197.

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

characteristics:

If no VLAN is supplied by the RADIUS server or if 802.1x authentication is disabled, the port is configured in its

access VLAN after successful authentication. Recall that an access VLAN is a VLAN assigned to an access port. All

packets sent from or received on this port belong to this VLAN.

If 802.1x authentication is enabled but the VLAN information from the RADIUS server is not valid, authorization fails

and configured VLAN remains in use. This prevents ports from appearing unexpectedly in an inappropriate VLAN

because of a configuration error.

Configuration errors could include specifying a VLAN for a routed port, a malformed VLAN ID, a nonexistent or

internal (routed port) VLAN ID, an RSPAN VLAN, a shut down or suspended VLAN. In the case of a 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.

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Configuring IEEE 802.1x Port-Based Authentication

Information About Configuring IEEE 802.1x Port-Based Authentication

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 Configuring Vendor-Specific RADIUS Attributes: Examples, page 185.

Voice Aware 802.1x Security

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 reenabled. If error-disabled recovery is not configured for the port,

you reenable it by using the shutdown and no-shutdown interface configuration commands.

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Information About Configuring IEEE 802.1x Port-Based Authentication

You can reenable 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.

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 Configuring Network Security with ACLs, page 575

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 Configuring Vendor-Specific RADIUS Attributes: Examples, page 185.

For more information about configuring ACLs, see Configuring Network Security with ACLs, page 575

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 Authentication Manager, page 194.

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Configuring IEEE 802.1x Port-Based Authentication

Information About Configuring IEEE 802.1x Port-Based Authentication

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.

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.

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Information About Configuring IEEE 802.1x Port-Based Authentication

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 Authentication Manager, page 194 and Configuring 802.1x Authentication with

Downloadable ACLs and Redirect URLs, page 231.

VLAN ID-Based MAC Authentication

You can use VLAN ID-based MAC authentication if you want 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.)

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Configuring IEEE 802.1x Port-Based Authentication

Information About Configuring IEEE 802.1x Port-Based Authentication

For configuration information, see Configuring Optional 802.1x Authentication Features, page 224. Additional

configuration is similar MAC authentication bypass, as described in Configuring 802.1x User Distribution, page 229.

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 port is

automatically set to multi-host mode.

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, a private VLAN, or a voice VLAN as an 802.1x guest VLAN.

The guest VLAN feature is not supported on internal VLANs (routed ports) or trunk ports; it is supported only on access

ports.

The switch supports MAC authentication bypass. When MAC authentication bypass is enabled on an 802.1x port, the

switch can authorize clients based on the client MAC address when 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 802.1x Authentication

with MAC Authentication Bypass, page 210.

For more information, see Configuring a Guest VLAN, page 226.

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Information About Configuring IEEE 802.1x Port-Based Authentication

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 reauthentication attempt. A port in the restricted

VLAN tries to reauthenticate at configured intervals (the default is 60 seconds). If reauthentication fails, the port remains

in the restricted VLAN. If reauthentication is successful, the port moves either to the configured VLAN or to a VLAN sent

by the RADIUS server. You can disable reauthentication. If you do this, the only way to restart the authentication process

is for the port to receive a link down or EAP logoff event. We recommend that you keep reauthentication 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, a primary private VLAN, or a voice VLAN as an 802.1x

restricted VLAN. The restricted VLAN feature is not supported on internal VLANs (routed ports) or trunk ports; it is

supported only on access ports.

Other security features such as dynamic ARP inspection, DHCP snooping, and IP source guard can be configured

independently on a restricted VLAN.

For more information, see Configuring a Restricted VLAN, page 226.

802.1x Authentication with Inaccessible Authentication Bypass

Use the inaccessible authentication bypass feature, also referred to as critical authentication or the AAA fail policy, when

the switch cannot reach the configured RADIUS servers and new hosts cannot be authenticated. You can configure the

switch to connect those hosts to critical ports.

When a new host tries to connect to the critical port, that host is moved to a user-specified access VLAN, the critical

VLAN. The administrator gives limited authentication to the hosts.

When the switch tries to authenticate a host connected to a critical port, the switch checks the status of the configured

RADIUS server. If a server is available, the switch can authenticate the host. However, if all the RADIUS servers are

unavailable, the switch grants network access to the host and puts the port in the critical-authentication state, which is

a special case of the authentication state.

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Configuring IEEE 802.1x Port-Based Authentication

Information About Configuring IEEE 802.1x Port-Based Authentication

Support on Multiple-Authentication Ports

When a port is configured on any host mode and the AAA server is unavailable, the port is then configured to multi-host

mode and moved to the critical VLAN. To support this inaccessible bypass on multiple-authentication (multiauth) ports,

use the authentication event server dead action reinitialize vlan vlan-id command. When a new host tries to connect

to the critical port, that port is reinitialized and all the connected hosts are moved to the user-specified access VLAN.

This command is supported on all host modess.

Authentication Results

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

If the port is unauthorized when a host connected to a critical port tries to authenticate and all servers are unavailable,

the switch puts the port in the critical-authentication state in the RADIUS-configured or user-specified access VLAN.

If the port is already authorized and reauthentication occurs, the switch puts the critical port in the

critical-authentication state in the current VLAN, which might be the one previously assigned by the RADIUS server.

If the RADIUS server becomes unavailable during an authentication exchange, the current exchange times out, and

the switch puts the critical port in the critical-authentication state during the next authentication attempt.

You can configure the critical port to reinitialize hosts and move them out of the critical VLAN when the RADIUS server

is again available. When this is configured, all critical ports in the critical-authentication state are automatically

reauthenticated. For more information, see Configuring Inaccessible Authentication Bypass, page 227.

Feature Interactions

Inaccessible authentication bypass interacts with these features:

Guest VLAN—Inaccessible authentication bypass is compatible with guest VLAN. When a guest VLAN is enabled on

8021.x port, the features interact as follows:

— If at least one RADIUS server is available, the switch assigns a client to a guest VLAN when the switch does not

receive a response to its EAP request/identity frame or when EAPOL packets are not sent by the client.

— If all the RADIUS servers are not available and the client is connected to a critical port, the switch authenticates

the client and puts the critical port in the critical-authentication state in the RADIUS-configured or

user-specified access VLAN.

— If all the RADIUS servers are not available and the client is not connected to a critical port, the switch might not

assign clients to the guest VLAN if one is configured.

— If all the RADIUS servers are not available and if a client is connected to a critical port and was previously

assigned to a guest VLAN, the switch keeps the port in the guest VLAN.

Restricted VLAN—If the port is already authorized in a restricted VLAN and the RADIUS servers are unavailable, the

switch puts the critical port in the critical-authentication state in the restricted VLAN.

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

Private VLAN—You can configure inaccessible authentication bypass on a private VLAN host port. The access VLAN

must be a secondary private VLAN.

Voice VLAN—Inaccessible authentication bypass is compatible with voice VLAN, but the RADIUS-configured or

user-specified access VLAN and the voice VLAN must be different.

Remote Switched Port Analyzer (RSPAN)—Do not configure an RSPAN VLAN as the RADIUS-configured or

user-specified access VLAN for inaccessible authentication bypass.

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Configuring IEEE 802.1x Port-Based Authentication

Information About Configuring IEEE 802.1x Port-Based Authentication

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.

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 Configuring Voice VLAN, page 327

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.

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Information About Configuring IEEE 802.1x Port-Based Authentication

802.1x Authentication with MAC Authentication Bypass

You can configure the switch to authorize clients based on the client MAC address (see Figure 19 on page 191) 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 reauthentication occurs, the switch uses 802.1x

authentication as the preferred reauthentication 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 reauthenticated. The reauthentication process is the

same as that for clients that were authenticated with 802.1x. During reauthentication, the port remains in the previously

assigned VLAN. If reauthentication is successful, the switch keeps the port in the same VLAN. If reauthentication fails,

the switch assigns the port to the guest VLAN, if one is configured.

If reauthentication 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 reauthentication. If MAC

authentication bypass is enabled and the 802.1x authentication times out, the switch uses the MAC authentication

bypass feature to initiate reauthorization. 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 802.1x Authentication with Port Security, page 209.

Voice VLAN—See 802.1x Authentication with Voice VLAN Ports, page 209.

VLAN Membership Policy Server (VMPS)—802.1x and VMPS are mutually exclusive.

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

Network admission control (NAC) Layer 2 IP validation—This feature takes effect after an 802.1x port is authenticated

with MAC authentication bypass, including hosts in the exception list.

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.

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Information About Configuring IEEE 802.1x Port-Based Authentication

For more configuration information, see Authentication Manager, page 194.

Cisco IOS Release 12.2(55)SE and later supports filtering of verbose MAB system messages. See Authentication

Manager CLI Commands, page 195.

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 Configuring 802.1x User Distribution, page 229.

Network Admission Control Layer 2 802.1x Validation

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 reauthentication attempts as the value of the Session-Timeout RADIUS attribute

(Attribute[27]) and get an access policy against the client from the RADIUS server.

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Information About Configuring IEEE 802.1x Port-Based Authentication

Set the action to be taken when the switch tries to reauthenticate 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 reauthentication process starts.

Set the list of VLAN number or name or VLAN group name as the value of the Tunnel Group Private ID (Attribute[81])

and the preference for the VLAN number or name or VLAN group name as the value of the Tunnel Preference

(Attribute[83]). If you do not configure the Tunnel Preference, the first Tunnel Group Private ID (Attribute[81])

attribute is picked up from the list.

View the NAC posture token, which shows the posture of the client, by using the show authentication privileged

EXEC command.

Configure secondary private VLANs as guest VLANs.

Configuring NAC Layer 2 802.1x 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 Configuring NAC Layer 2 802.1x Validation, page 229 and the Configuring Periodic Reauthentication, page 223.

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

For more configuration information, see Authentication Manager, page 194.

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 the configuration

commands, see Configuring Optional 802.1x Authentication Features, page 224

Open1x Authentication

Open1x authentication allows a device access to a port before that device is authenticated. When open authentication

is configured, a new host can pass traffic according to the access control list (ACL) defined on the port. After the host

is authenticated, the policies configured on the RADIUS server are applied to that host.

You can configure open authentication with these scenarios:

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

authentication.

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

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

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

For more information see Configuring the Host Mode, page 222.

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.

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.

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Information About Configuring IEEE 802.1x Port-Based Authentication

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.

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 23 on page 213.

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 23

Authenticator and Supplicant Switch using CISP

Workstations (clients)

Supplicant switch (outside wiring closet)

Authenticator switch

Access control server (ACS)

Trunk port

802.1x Supplicant and Authenticator Switch 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 to 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.

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Configuring IEEE 802.1x Port-Based Authentication

Information About Configuring IEEE 802.1x Port-Based Authentication

For more information, see Configuring an Authenticator, page 230.

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

Attribute

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 configured, 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.

Authentication Manager 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)

Default 802.1x Authentication Settings

Table 30 on page 214 shows the default 802.1x authentication settings.

Table 30

Default 802.1x Authentication Settings

Feature

Default Setting

Switch 802.1x enable state

Disabled.

Per-port 802.1x enable state

Disabled (force-authorized).

The port sends and receives normal traffic without 802.1x-based

authentication of the client.

AAA

Disabled.

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Information About Configuring IEEE 802.1x Port-Based Authentication

Table 30

Default 802.1x Authentication Settings (continued)

Feature

Default Setting

RADIUS server

IP address

None specified.

UDP authentication port

1812.

Key

None specified.

Host mode

Single-host mode.

Control direction

Bidirectional control.

Periodic reauthentication

Disabled.

Number of seconds between

3600 seconds.

reauthentication attempts

Reauthentication number

2 times (number of times that the switch restarts the authentication process

before the port changes to the unauthorized state).

Quiet period

60 seconds (number of seconds that the switch remains in the quiet state

following a failed authentication exchange with the client).

Retransmission time

30 seconds (number of seconds that the switch should wait for a response to

an EAP request/identity frame from the client before resending the request).

Maximum retransmission number

2 times (number of times that the switch will send an EAP-request/identity

frame before restarting the authentication process).

Client timeout period

30 seconds (when relaying a request from the authentication server to the

client, the amount of time the switch waits for a response before resending the

request to the client.)

Authentication server timeout period

30 seconds (when relaying a response from the client to the authentication

server, the amount of time the switch waits for a reply before resending the

response to the server.)

You can change this timeout period by using the authentication timer server

interface configuration command.

Inactivity timeout

Disabled.

Guest VLAN

None specified.

Inaccessible authentication bypass

Disabled.

Restricted VLAN

None specified.

Authenticator (switch) mode

None specified.

MAC authentication bypass

Disabled.

Voice-aware security

Disabled

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:

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

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Cisco Industrial Ethernet 4000, 4010 and 5000 Switch Software. Configuration Guide (2022) - page 9