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BPDU Filter

Maybe you don’t want a port to send BPDUs. This effectively turns off spanning-tree.

Warning

This feature melts networks. It disables spanning tree.

Caution

This is not deterministic. It works differently per port, vs globally.

From the IOS-XE config guide

The BPDU filtering feature can be globally enabled on the switch or can be enabled per interface, but the feature operates with some differences.

Enabling BPDU filtering on PortFast enabled interfaces at the global level keeps those interfaces that are in a PortFast operational state from sending or receiving BPDUs.

The interfaces still send a few BPDUs at link-up before the switch begins to filter outbound BPDUs. You should globally enable BPDU filtering on a switch so that hosts that are connected to these interfaces do not receive BPDUs. If a BPDU is received on a PortFast enabled interface, the interface loses its PortFast operational status, and BPDU filtering is disabled.

Enabling BPDU filtering on an interface without also enabling the PortFast feature keeps the interface from sending or receiving BPDUs.

Globally

If a port, is running portfast, this feature will transmit a few BPDUs when the port first turns on.

spanning-tree portfast bpdufilter default

Per Interface

This port will never send BPDUs.

interface 1
  spanning-tree bpdufilter enable

References

Layer 2 Configuration Guide, Cisco IOS XE 26.x.x (Catalyst 9300 Switches) - Configuring Optional Spanning-Tree Features Cisco IOS XE 26 - Cisco

Last Modified • Thursday, June 4, 2026. 10:22 pm UTC+00:00 • Commit: 6317c70