(also bridge protocol data unit frame, BPDU, BPDU frame)
A bridge protocol data unit is a frame (a single network packet used in data transmission) with information on the spanning tree protocol (a protocol used to prevent loops that lead to broadcast storms and network instability). Using bridge protocol data unit frames, switches can determine the best paths to the root bridge, identify redundant ones, and block those that have the potential to loop the network.
See also: digital switch, packet switched network, virtual switch, jumbo frame, logical topology
Bridge protocol data units contain information about the sending switch and its priority, the port on which the packet was sent, and the network topology (such as the root bridge, the path cost, and the status of ports on the switch).