Telindus 1031, Руководство пользователя и справочник

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Telindus 1031 Router Chapter 8
User manual Configuring the bridge
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8.5 The Spanning Tree bridge port states
Bridge port states
There are four possible states a bridge port can be in:
Bridge port state transition diagram
The following figure shows how a bridge port moves
through the different states when the bridge is powered:
When you enable Spanning Tree, every bridge in the net-
work goes through the transitory states of listening and
learning at power up. If properly configured, each port sta-
bilises to the forwarding or blocking state.
When the spanning-tree algorithm places a port in the for-
warding state, the following process occurs:
1. The port is put into the listening state while it waits for
protocol information that suggests it should go to the
blocking state.
2. The port waits for the expiration of the forward delay
timer, moves the port to the learning state, and resets
the forward delay timer.
3. In the learning state, the port continues to block frame
forwarding as it learns station location information for
the forwarding database.
4. The port waits for the expiration of the forward delay
timer and then moves the port to the forwarding state, where both learning and forwarding are ena-
bled.
State A port in this state …
blocking • does no frame forwarding.
• does not incorporate station location into its address database (There is no
learning on a blocking port, so there is no MAC address database update.).
• receives BPDUs, but does not process or propagate them.
A bridge always enters the blocking state following bridge initialisation.
listening • does no frame forwarding.
• does not incorporate station location into its address database (There is no
learning on a listening port, so there is no MAC address database update.).
• receives and processes BPDUs, but does not propagate them.
learning • does no frame forwarding.
• incorporates station location into its MAC address database.
• receives, processes and propagates BPDUs.
forwarding • forwards frames.
• incorporates station location into its MAC address database.
• receives, processes and propagates BPDUs.
Power-on
initialisation
Blocking
state
Listening
state
Learning
state
Forwarding
state
Disabled
state
Forward delay
Forward delay