Use Models for 802.1X Open VLAN Modes

You can apply the 802.1X Open VLAN mode in more than one way. Depending on your use, you will need to create one or two static VLANs on the switch for exclusive use by per-port 802.1X Open VLAN mode authentication:
  • Unauthorized-Client VLAN: Configure this VLAN when unauthenticated, friendly clients will need access to some services before being authenticated or instead of being authenticated.

  • Authorized-Client VLAN: Configure this VLAN for authenticated clients when the port is not statically configured as an untagged member of a VLAN you want clients to use, or when the port is statically configured as an untagged member of a VLAN you do not want clients to use. (A port can be configured as untagged on only one port-based VLAN. When an Authorized-Client VLAN is configured, it will always be untagged and will block the port from using a statically configured, untagged membership in another VLAN.) Note that after client authentication, the port returns to membership in any tagged VLANs for which it is configured.

802.1X per-port configuration

802.1X Per-Port Configuration

Port Response

No Open VLAN mode:

The port automatically blocks a client that cannot initiate an authentication session.

Open VLAN mode with both of the following configured:

Unauthorized-Client VLAN

  • When the port detects a client without 802.1X supplicant capability, it automatically becomes an untagged member of this VLAN. If you previously configured the port as a static, tagged member of the VLAN, membership temporarily changes to untagged while the client remains unauthenticated.

  • If the port already has a statically configured, untagged membership in another VLAN, then the port temporarily closes access to this other VLAN while in the Unauthorized-Client VLAN.

  • To limit security risks, the network services and access available on the Unauthorized-Client VLAN should include only what a client needs to enable an authentication session. If the port is statically configured as a tagged member of any other VLANs, access to these VLANs is blocked while the port is a member of the Unauthorized-Client VLAN.

 

Note for a Port Configured To Allow Multiple Client Sessions: If any previously authenticated clients are using a port assigned to a VLAN other than the Unauthorized-Client VLAN, then a later client that is not running 802.1X supplicant software is blocked on the port until all other, authenticated clients on the port have disconnected.

Authorized-Client VLAN

  • After client authentication, the port drops membership in the Unauthorized-Client VLAN and becomes an untagged member of this VLAN.
    NOTE:

    If the client is running an 802.1X supplicant application when the authentication session begins, and is able to authenticate itself before the switch assigns the port to the Unauthorized-Client VLAN, then the port does not become a member of the Unauthorized-Client VLAN. On the switches covered in this guide, you can use the unauth-period command to delay moving the port into the Unauthorized-Client VLAN.

    If RADIUS authentication assigns a VLAN and there are no other authenticated clients on the port, then the port becomes a member of the RADIUS-assigned VLAN —instead of the Authorized-Client VLAN—while the client is connected.
    • If the port is statically configured as a tagged member of a VLAN, and this VLAN is used as the Authorized-Client VLAN, then the port temporarily becomes an untagged member of this VLAN when the client becomes authenticated. If the port is statically configured as a tagged member of a VLAN, the port returns to tagged membership in this VLAN upon.

Open VLAN Mode with Only an Unauthorized-Client VLAN Configured:

  • When the port detects a client, it automatically becomes an untagged member of this VLAN. To limit security risks, the network services and access available on this VLAN should include only what a client needs to enable an authentication session. If the port is statically configured as an untagged member of another VLAN, the switch temporarily removes the port from membership in this other VLAN while membership in the Unauthorized-Client VLAN exists.

  • After the client is authenticated, and if the port is statically configured as an untagged member of another VLAN, the port’s access to this other VLAN is restored.
    NOTE:

    If RADIUS authentication assigns the port to a VLAN, this assignment overrides any statically configured, untagged VLAN membership on the port (while the client is connected).

  • If the port is statically configured as a tagged member of a VLAN, the port returns to tagged membership in this VLAN upon successful client authentication. This happens even if the RADIUS server assigns the port to another, authorized VLAN. Note that if the port is already configured as a tagged member of a VLAN that RADIUS assigns as an authorized VLAN, then the port becomes an untagged member of that VLAN for the duration of the client connection.
    NOTE:

    for a Port Configured To Allow Multiple Client Sessions: If any previously authenticated clients are using a port assigned to a VLAN other than the Unauthorized-Client VLAN (such as a RADIUS-assigned VLAN), then a later client that is not running 802.1X supplicant software is blocked on the port until all other, authenticated clients on the port have disconnected.

Open VLAN Mode with Only an Authorized-Client VLAN Configured

Port automatically blocks a client that cannot initiate an authentication session.

 

f the client successfully completes an authentication session, the port becomes an untagged member of this VLAN.

 
If the port is statically configured as a tagged member of any other VLAN, the port returns to tagged membership in this VLAN upon successful client authentication. This happens even if the RADIUS server assigns the port to another, authorized VLAN. If the port is already configured as a tagged member of a VLAN that RADIUS assigns as an authorized VLAN, then the port becomes an untagged member of that VLAN for the duration of the client connection.
NOTE:

An authorized-client VLAN configuration can be overridden by a RADIUS authentication that assigns a VLAN.