Cisco site does not specify that in listening state the switch sends BPDU. however my Self-study book(frahim) says that BPDUs are sent... where is the truth??? During listeng state switches should create their active topologies: how is possible if bpdu are not sent and we have 3 switches interconnected(each of them in listening state).
from:
A port in the listening state performs as follows: Discards frames received from the attached segment. Discards frames switched from another port for forwarding. Does not incorporate station location into its address database. (There is no learning at this point, so there is no address database update.) Receives BPDUs and directs them to the system module. Processes BPDUs received from the system module. Receives and responds to network management messages.
Learning State A port in the learning state is preparing to participate in frame forwarding. This is the second transitional state through which a port moves in anticipation of frame forwarding. The port enters the learning state from the listening state through the operation of Spanning-Tree Protocol. A port in the learning state performs as follows: Discards frames received from the attached segment. Discards frames switched from another port for forwarding. Incorporates station location into its address database. Receives BPDUs and directs them to the system module. Receives, processes, and transmits BPDUs received from the system module. Receives and responds to network management messages.