Interlogix NS3500-28T-4S User Manual - Manual (Page 141)

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after a topology change.
Each port on a switch using STP exists is in one of the following five states:
 Blocking – the port is blocked from forwarding or receiving packets
 Listening – the port is waiting to receive BPDU packets that may tell the port to go back to the blocking
state
 Learning – the port is adding addresses to its forwarding database, but not yet forwarding packets
 Forwarding – the port is forwarding packets
 Disabled – the port only responds to network management messages and must return to the blocking
state first
A port transitions from one state to another as follows:
 From initialization (switch boot) to blocking
 From blocking to listening or to disabled
 From listening to learning or to disabled
 From learning to forwarding or to disabled
 From forwarding to disabled
 From disabled to blocking
Figure 4-6-1 STP Port State Transitions