CISCO – Spanning Tree Enhancements


Loop Guard

This feature prevents a port from erroneously transitioning from blocking state to forwarding when the port stops receiving BPDUs. The port is marked as being in loop-inconsistent state. In this state, the port does not forward packets. The possible values are Enable or Disable.

TCN Guard

Enabling the TCN Guard feature restricts the port from propagating any topology change information received through that port. This means that even if a port receives a BPDU with the topology change flag set to true, the port will not flush its MAC address table and send out a BPDU with a topology change flag set to true.

Auto Edge

Enabling the Auto Edge feature allows the port to become an edge port if it does not see BPDUs for some duration.

BPDU Filter

When enabled, this feature filters the BPDU traffic on this port when STP is enabled on this port.

BPDU Flood

When enabled, the BPDU Flood feature floods the BPDU traffic arriving on this port when STP is disabled on this port.

Ref: cisco training online

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