ZyXEL Communications GS1350 Series User Manual page 350

Figure 257 Loop Guard – Probe Packet
The Switch also shuts down port N if the probe packet returns to switch A on any other port. In other
words loop guard also protects against standard network loops.
The following figure illustrates three switches forming a loop. A sample path of the loop guard probe
packet is also shown. In this example, the probe packet is sent from port N and returns on another port.
As long as loop guard is enabled on port N. The Switch will shut down port N if it detects that the probe
packet has returned to the Switch.
Figure 258 Loop Guard – Network Loop
Note: After resolving the loop problem on your network you can re-activate the disabled port
via the Web Configurator or via commands (See the CLI Reference Guide).
Click Switching > Loop Guard in the navigation panel to display the screen as shown.
Note: The loop guard feature cannot be enabled on the ports that have Spanning Tree
Protocol (RSTP) enabled.
Figure 259 Switching > Loop Guard
GS1350 Series User's Guide
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