Quick Reference Guide

PowerConnect B-Series TI24X Configuration Guide 131

53-1002269-02

Configuring STP related features

After convergence is complete, Figure 20 shows the active Layer 2 path of the topology in

Figure 19.

FIGURE 20 Active Layer 2 path in complex topology

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.

Bridge priority = 1000

Bridge priority = 200

Bridge priority = 60

Bridge priority = 300

Bridge priority = 400

Bridge priority = 900

Port3

Port2

Port4

Port5

Port7

Port8

Indicates the active Layer 2 path

Switch 1

Switch 3

Switch 4

Switch 6

Switch 5

Switch 2