A bridge that examines the destination address of an incoming frame, consults an address table, and forwards the frame only over the link toward the target device. If the frame is intended for a station on the same LAN segment, the bridge simply ignores it, rather than passing it on. Since the frames are not forwarded across other links, a filtering bridge does a great deal to relieve overall congestion on a segment-by-segment basis. Most bridges are self-learning, filtering bridges and are standardized in IEEE 802.1D, which describes the spanning tree protocol (STP). See also bridge, self-learning bridge, and STP.