RSTP protocol frames
An RSTP BPDU uses the same format as an STP BPDU except that a Version1 length field is added to the payload of RSTP BPDUs. The differences between an RSTP BPDU and an STP BPDU are as follows:
Protocol version ID—The value is 0x02 for RSTP.
BPDU type—The value is 0x02 for RSTP BPDUs.
Flags—All 8 bits are used.
Version1 length—The value is 0x00, which means no version 1 protocol information is present.
RSTP does not use TCN BPDUs to advertise topology changes. RSTP floods BPDUs with the TC flag set in the network to advertise topology changes.