Siemens S323, S223 user manual Bpdu Hop, Bpdu Filter, Bpdu Guard, Following command

UMN:CLI	User Manual
	SURPASS hiD 6615 S223/S323 R1.5

To delete a configured max age, use the following command.

	Command	Mode	Description
	no stp mst max-age		Returns to the default max-age value of STP, RSTP
			and MSTP.
		Bridge
	no stp pvst max-age VLAN-		Returns to the default max-age value of PVSTP and
	RANGE		PVRSTP.
8.3.9.4	BPDU Hop
	In MSTP, it is possible to configure the number of hop in order to prevent BPDU from
	wandering. BPDU passes the switches as the number of hop by this function.
	To configure the number of hop of BPDU in MSTP, use the following command.
	Command	Mode	Description
	stp mst max-hops <1-40>		Configures the number of hop for BPDU, set the num-
		Bridge	ber of possible hops in the region.
	no stp mst max-hops		Deletes the number of hop for BPDU in MSTP.
8.3.9.5	BPDU Filter
	BPDU filtering allows you to avoid transmitting on the ports that are connected to an end
	system. If the BPDU Filter feature is enabled on the port, then incoming BPDUs will be fil-
	tered and BPDUs will not be sent out of the port. To set the BPDU filter on the port, use
	the following command.
	Command	Mode	Description
	stp bpdu-filter {enable disable}		Forbids all STP BPDUs to go out the specific port and
		Bridge	not to recognize incoming STP BPDUs the specific
	PORTS
			port.

By default, it is disabled. The BPDU filter-enabled port acts as if STP is disabled on the port. This feature can be used for the ports that are usually connected to an end system or the port that you don’t want to receive and send unwanted BPDU packets. Be cautious about using this feature on STP enabled uplink or trunk port. If the port is removed from VLAN membership, correspond BPDU filter will be automatically deleted.

8.3.9.6BPDU Guard

BPDU guard has been designed to allow network designers to enforce the STP domain borders and keep the active topology predictable. The devices behind the ports with STP enabled are not allowed to influence the STP topology. This is achieved by disabling the port upon receipt of BPDU. This feature prevents Denial of Service (DoS) attack on the network by permanent STP recalculation. That is caused by the temporary introduction and subsequent removal of STP devices with low (zero) bridge priority.

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