Chapter 4: Web management
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NS3550-8T-2S Industrial Managed Switch User Manual
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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.
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Learning
–
The port is adding addresses to its forwarding database, but not yet
forwarding packets.
•
Forwarding
–
The port is forwarding packets.
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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.
You can modify each port state by using management software. When STP is enabled,
every port on every switch in the network goes through the blocking state and then
transitions through the states of listening and learning at power up. If properly
configured, each port stabilizes to the forwarding or blocking state. No packets (except
BPDUs) are forwarded from, or received by, STP-enabled ports until the forwarding
state is enabled for that port.
