VLAN authentication

Note:

VLAN authentication is only supported on 7210 SAS-Dxp.

The 7210 SAS supports VLAN authentication, which operates similarly to 802.1x network access control but only uses VLAN-tagged EAPOL frames to trigger the authentication process on a per-VLAN basis, or uses null-tagged EAPOL frames to authenticate and authorize processing of service traffic received in the context of a Dot1q explicit null SAP. See 802.1x network access control for information about 802.1x network access control and authentication.

To authenticate a port using VLAN authentication, you must first configure 802.1x authentication on the 7210 SAS by enabling port-control auto, and then configure vlan-auth on the 7210 SAS to enable VLAN authentication and allow VLAN authentication functionality to supersede that of basic 802.1x authentication.

VLAN authentication and MAC authentication are mutually exclusive. MAC authentication cannot be configured on a port while VLAN authentication is already configured on the same port. See MAC authentication for information about MAC authentication.

Layer 2 control protocols affect VLAN authentication behavior differently depending on the protocol in use; see Layer 2 control protocol interaction with authentication methods for more information.

VLAN authentication basics

When a port becomes operationally up with VLAN authentication enabled, the 7210 SAS (as the authenticator) performs the following steps.

  1. After transmission of the first EAP-Request/ID PDU, the 7210 SAS begins listening on the port for VLAN-tagged EAPOL Start, Request-Identity frames from the access device connected to the port. Null-tagged EAPOL frames also trigger the authentication process if a Dot1q explicit null SAP is configured.

  2. If the 7210 SAS receives a VLAN-tagged EAPOL frame (or a null-tagged EAPOL frame if a Dot1q explicit null SAP is configured), the 7210 SAS transmits the frame to the configured RADIUS server for comparison of the VLAN against the usernames configured in its database.

    The User-Name attribute is contained in the RADIUS message. This attribute specifies the username received in the EAPOL frame from the client device.

  3. If the VLAN is approved by the RADIUS server, the 7210 SAS maps all traffic received from the VLAN to a SAP and processes it in the context of the configured service.

    If the VLAN is rejected by the RADIUS server, all traffic from the VLAN is dropped. The 7210 SAS enters a quiet period, configured using the quiet-period command, and will not authenticate the port using VLAN authentication. After the quiet period expires, the 7210 SAS returns to step1.

While the port is unauthenticated, the port will be down to all upper layer protocols or services.

VLAN authentication limitations

VLAN authentication is subject to the following limitations:

  • VLAN authentication is only supported on Dot1q-encapsulated ports. It is not supported on NULL or QinQ-encapsulated ports.

  • VLAN authentication only uses the outermost VLAN tag received in the packets. Packets with more than one tag are processed only if the outermost tag matches the SAP tag.

  • Restrictions on processing of SAP tags also apply to VLAN authenticated frames. VLAN authentication does not change the current behavior for frames mapped to different SAPs and services.

  • VLAN range SAPs are not supported on a port with VLAN authentication enabled.

  • Dot1q default SAPs configured on a port with Dot1q encapsulation do not support VLAN authentication.

  • Dot1q explicit null SAPs can be configured on a port with Dot1q encapsulation, which requires authentication of null-tagged EAPOL frames.

Dynamic VLAN assignment using dot1x RADIUS authentication with EHS

Note:

Dynamic VLAN assignment using dot1x RADIUS authentication with EHS is only supported on the 7210 SAS-Dxp.

On the 7210 SAS, users can assign a VLAN using the RADIUS tunnel attribute. Only the VLAN is returned by RADIUS, while other policies (such as QoS, ACLs, or accounting) are not. The locally configured policies can be applied when the VLAN ID is used to configure the SAP after a successful authentication of the host using dot1x (including MAC authentication).

See the 7210 SAS-D, Dxp, K 2F1C2T, K 2F6C4T, K 3SFP+ 8C Services Guide and 7210 SAS-D, Dxp, K 2F1C2T, K 2F6C4T, K 3SFP+ 8C System Management Guide for more information and configuration guidelines on dynamic VLAN assignment using dot1x RADIUS authentication with the event handling system (EHS).