In RSTP (Rapid Spanning Tree Protocol) mode, alternate and backup ports are designed to provide a backup path in case the designated path fails. These ports do not forward user traffic under normal conditions, but they can receive, process, and send BPDUs (Bridge Protocol Data Units) in order to participate in the STP calculations. Therefore, the statement that in RSTP mode, alternate and backup ports cannot forward user traffic but can receive, process, and send BPDU is true.