Which switch feature immediately transitions a port to forwarding when the link comes up?

PortFast immediately transitions a switch port to the forwarding state, bypassing the normal Spanning Tree Protocol (STP) listening and learning states. This is ideal for end-device ports (like those connected to PCs or servers) where temporary loops are not expected and fast connectivity is desired. BPDU guard disables a port if it receives a Bridge Protocol Data Unit (BPDU), preventing unauthorized switches from interfering with STP. UplinkFast and BackboneFast are STP convergence enhancements that speed up the recovery process when a direct or indirect link failure occurs, respectively, but they do not immediately transition a port to forwarding upon link up.