Cisco WS-C4003 Software Guide - Page 104

How Spanning Tree Protocols Work Chapter 7 Configuring Spanning Tree Listening State The listening state is the first transitional state a port enters after the blocking state. The port enters this state when the spanning tree determines that the port should participate in frame forwarding. Learning is disabled in the listening state. Figure 7-4 shows a port in the listening state. Figure 7-4 Port 2 in Listening State All segment frames Forwarding Station addresses Port 1 BPDUs Network management and data frames Filtering database System module Frame forwarding Data frames BPDUs Port 2 Network management frames S5693 Listening All segment frames BPDU and network management frames 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. Software Configuration Guide-Catalyst 4000 Family, Catalyst 2948G, Catalyst 2980G, Releases 6.3 and 6.4 7-8 78-12647-02