Defines the mode of operation of all the registrar state machines associated to the port. normal - registration as well as de-registration of VLANs are allowed. fixed - A VLAN that was previously mapped onto such a port either dynamically or statically cannot be de-registered through GVRP. When the port registration mode is set to fixed, VLAN(s) can only be mapped onto such port statically. forbidden - dynamic VLAN registration or de-registration are not allowed on the port. NOTE: The registrar state machines for the default VLAN will operate in Fixed Registration Mode for all the ports on the switch.