How Does a Switch Process BPDUs?

On the S5720-EI, S5720-HI, S5730-HI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S5735-L, S5735S-L, S5735S-L-M, S5735-S, S5735-S-I, S5735S-S, S6720-EI, S6720-HI, S6720S-EI, S6730-H, S6730S-H, S6730-S, and S6730S-S, an interface directly discards BPDUs by default. If BPDUs of a protocol need to be sent to the CPU for processing, enable functions of the protocol. For example, if STP BPDUs need to be sent to the CPU for processing, enable STP globally and on the interface.
On other models, BPDUs are sent to the CPU for processing by default. If BPDUs do not need to be sent to the CPU for processing, run the bpdu disable command to configure an interface to directly discard BPDUs.