General operating rules and notes

  • In the user-based mode, when there is an authenticated client on a port, the following traffic movement is allowed:
    • Multicast and broadcast traffic

    • Unicast traffic to authenticated clients

    • All traffic from authenticated clients.

  • When a port on the switch is configured as either an authenticator or supplicant and is connected to another device, rebooting the switch causes a reauthentication of the link.

  • Using user-based 802.1X authentication, when a port on the switch is configured as an authenticator the port allows only authenticated clients up to the currently configured client limit. For clients without proper 802.1X supplicant software, the optional 802.1X Open VLAN mode can be used to open a path for downloading 802.1X supplicant software to a client or to provide other services for unauthenticated clients. See 802.1X Open VLAN mode.

  • Using port-based 802.1X authentication when a port on the switch is configured as an authenticator, one authenticated client opens the port. Other clients not running an 802.1X supplicant application can have access to the switch and network through the opened port. If another client uses an 802.1X supplicant application to access the opened port, reauthentication occurs using the RADIUS configuration response for the latest client to authenticate. To control access by all clients, use the user-based method.

  • Where a switch port is configured with user-based authentication to accept multiple 802.1X (and/or web- or MAC authentication) client sessions, all authenticated clients must use the same port-based, untagged VLAN membership assigned for the earliest, currently active client session. Thus, on a port where one or more authenticated client sessions are already running, all such clients will be on the same untagged VLAN. If a RADIUS server subsequently authenticates a new client, but attempts to reassign the port to a different, untagged VLAN than the one already in use for the previously existing, authenticated client sessions, the connection for the new client will fail. For more on this topic, see 802.1X Open VLAN mode.

    If the port is statically configured with any tagged VLAN memberships, any authenticated client configured to use these tagged VLANs will have access to them.

  • You can configure a port as both an 802.1X authenticator and an 802.1X supplicant.

  • On a port configured for 802.1X with RADIUS authentication, if the RADIUS server specifies a VLAN for the supplicant and the port is a trunk member, the port will be blocked. If the port is later removed from the trunk, the port will allow authentication of the supplicant. Similarly, if the supplicant is authenticated and later the port becomes a trunk member, the port will be blocked. If the port is removed from the trunk, it will allow the supplicant to reauthenticate.

  • If a client already has access to a switch port when you configure the port for 802.1X authenticator operation, the port will block the client from further network access until it can be authenticated.

  • Meshing is not supported on ports configured for 802.1X port-access security.

  • A port can be configured as an authenticator or an 802.1X supplicant, or both. Some configuration instances block traffic flow or allow traffic to flow without authentication. See Configuring switch ports to operate as supplicants for 802.1X connections to other switches.

  • To help maintain security, 802.1X and LACP cannot both be enabled on the same port. If you try to configure 802.1X on a port already configured for LACP (or the reverse), you will see a message similar to the following:
    Error configuring port X: LACP and 802.1X cannot be run together.

Applying web-based authentication or MAC authentication concurrently with port-based 802.1X authentication:

While 802.1X port-based access control can operate concurrently with Web Authentication or MAC Authentication, port-based access control is subordinate to web-based authentication and MAC authentication operation. If 802.1X operates in port-based mode and MAC or web-based authentication is enabled on the same port, any 802.1X authentication has no effect on the ability of a client to access the controlled port. That is, the client access will be denied until the client authenticates through web-based authentication or MAC authentication on the port. Note: A client authenticating with port-based 802.1X does not open the port in the same way that it does when web-based authentication or MAC authentication are not enabled. Any unauthenticated client attempting to access the port after another client authenticates with port-based 802.1X still has to authenticate through web or MAC.