Cisco CISCO1401 Software Guide - Page 109

Chapter 8 Configuring Spanning Tree Protocol Understanding Spanning Tree Protocol Note If a bridge port is blocked, some broadcast or multicast packets can reach a forwarding port on the bridge and cause the bridging logic to switch the blocked port into listening state momentarily before the packets are dropped at the blocked port. Listening State The listening state is the first state an interface enters after the blocking state. The interface enters this state when STP determines that the interface should participate in frame forwarding. An interface in the listening state performs as follows: • Discards frames received on the port • Does not learn addresses • Receives BPDUs Learning State An interface in the learning state prepares to participate in frame forwarding. The interface enters the learning state from the listening state. An interface in the learning state performs as follows: • Discards frames received on the port • Learns addresses • Receives BPDUs Forwarding State An interface in the forwarding state forwards frames. The interface enters the forwarding state from the learning state. An interface in the forwarding state performs as follows: • Receives and forwards frames received on the port • Learns addresses • Receives BPDUs Disabled State An interface in the disabled state does not participate in frame forwarding or in the spanning tree. An interface in the disabled state is nonoperational. A disabled interface performs as follows: • Discards frames received on the port • Does not learn addresses • Does not receive BPDUs OL-4059-01 Cisco Aironet 1400 Series Wireless Bridges Software Configuration Guide 8-7