802.1X Open VLAN operating notes

Although you can configure Open VLAN mode to use the same VLAN for both the Unauthorized-Client VLAN and the Authorized-Client VLAN, this is not recommended. Using the same VLAN for both purposes allows unauthenticated clients access to a VLAN intended only for authenticated clients, which poses a security breach.

While an Unauthorized-Client VLAN is in use on a port, the switch temporarily removes the port from any other statically configured VLAN for which that port is configured as a member. Note that the Menu interface will still display the port’s statically configured VLAN(s).

A VLAN used as the Unauthorized-Client VLAN should not allow access to resources that must be protected from unauthenticated clients.

If a port is configured as a tagged member of VLAN “X”, then the port returns to tagged membership in VLAN “X” upon successful client authentication. This happens even if the RADIUS server assigns the port to another, authorized VLAN “Y”. Note that if RADIUS assigns VLAN “X” as an authorized VLAN, then the port becomes an untagged member of VLAN “X” for the duration of the client connection. (If there is no Authorized-Client or RADIUS-assigned VLAN, then an authenticated client without tagged VLAN capability can access only a statically configured, untagged VLAN on that port.)

When a client’s authentication attempt on an Unauthorized-Client VLAN fails, the port remains a member of the Unauthorized-Client VLAN until the client disconnects from the port.

During an authentication session on a port in 802.1X Open VLAN mode, if RADIUS specifies membership in an untagged VLAN, this assignment overrides port membership in the Authorized-Client VLAN. If there is no Authorized-Client VLAN configured, then the RADIUS assignment overrides any untagged VLAN for which the port is statically configured.

If the only authenticated client on a port loses authentication during a session in 802.1X Open VLAN mode, the port VLAN membership reverts back to the Unauthorized-Client VLAN. If there is no Unauthorized-Client VLAN configured, then the client loses access to the port until it can reauthenticate itself. If there are multiple clients authenticated on the port, if one client loses access and attempts to re-authenticate, that client will be handled as a new client on the port.

The first client to authenticate on a port configured to support multiple clients will determine the port’s VLAN membership for any subsequent clients that authenticate while an active session is already in effect.