The 802.1d Spanning Tree Protocol dictates that a port must start out in the blocking state and transition through two other intermediate states (listening and learning), before it can begin forwarding frames. These state transitions help prevent temporary loops in the bridge topology. The switch implements a special algorithm where a singly-addressed port may move to the forwarding state as soon as it regains a previously lost linkbeat, or when it is enabled after having been suspended for address violation. This does not comply with the 802.1d STP in the strictest sense. To force compliance, this object may be set to enabled(1). The default value is disabled(2).