BPDU

In classic STP, only the root bridge originated BPDUs, and other switches just forwarded the BPDUs they received. In Rapid STP, all switches originate and send their own BPDUs from their designated ports.

Other differences

• All switches running Rapid STP send their own BPDUs every hello timer (2 seconds).

• Switches 'age' the BPDU information much more quickly. In classic STP, a switch waits for 10 hello intervals (20 seconds). In rapid STP, a switch considers a neighbor lost if it misses 3 BPDUs (6 seconds). It will then 'flush' all MAC addresses learned on that interface.