HP ProCurve 9304M Installation And Configuration Manual page 251

After convergence is complete, Figure 8.19 shows the active Layer 2 path of the topology in Figure 8.18.
Figure 8.19 Active Layer 2 Path in Complex Topology
Routing Switch 1
Bridge priority = 1000
Port3
Port2
Port3
Routing Switch 3
Bridge priority = 300
Propagation of Topology Change
The Topology Change state machine generates and propagates the topology change notification messages on
each port. When a Root port or a Designated port goes into a forwarding state, the Topology Change state
machine on those ports send a topology change notice (TCN) to all the bridges in the topology to propagate the
topology change.
NOTE: Edge ports, Alternate ports, or Backup ports do not need to propagate a topology change.
The TCN is sent in the RST BPDU that a port sends. Ports on other bridges in the topology then acknowledge the
topology change once they receive the RST BPDU, and send the TCN to other bridges until all the bridges are
informed of the topology change.
Configuring Spanning Tree Protocol (STP) and Advanced STP Features
Routing Switch 2
Bridge priority = 200
Port7
Port2 Port2
Port3
Port3
Port4 Port4
Routing Switch 4
Bridge priority = 400
Indicates the active Layer 2 path
Port8
Bridge priority = 60
Port5
Port2
Port4
Port4
Port5 Port5
Bridge priority = 900
Routing Switch 5
Port3
Port3
Routing Switch 6
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