Allied Telesis AT-S63 - Manual (Page 287)

AT-S63 Management Software Features Guide
Section V: Spanning Tree Protocols 287
Figure 41. Loop Guard Example 5
Switch 3
Switch 1
Old root bridge
RSTP stops operating
Port 4
Loop guard changes the
port to the blocking state
from the forwarding state
Switch 2
New root bridge
Port 14
Transitions from the blocking state
to the forwarding state