Spanning Tree Port States
When a port is first activated, it transitions through the following stages
shown in Table 3-2.
Table 3-2 Spanning Tree Port States
Port State Timer Actions
Blocking Max Age (20 sec) Discards frames, does not learn
MAC addresses, receives
BPDUs.
Listening Forward Delay (15 sec) Discards frames, does not learn
MAC addresses, receives
BPDUs to determine its role in
the network.
Learning Forward Delay (15 sec) Discards frames, does learn
MAC addresses, receives and
transmits BPDUs.
Forwarding Accepts frames, learns MAC
addresses, receives and
transmits BPDUs.