Siemens S223 User Manual

Page of 381
UMN:CLI                                                                                                                                                              User  Manual 
SURPASS hiD 6615 S223/S323 R1.5 
222                                                                         A50010-Y3-C150-2-7619 
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. 
no stp pvst max-age VLAN-
RANGE
 
Bridge 
Returns to the default max-age value of PVSTP and 
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-
ber of possible hops in the region. 
no stp mst max-hops 
Bridge 
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
PORTS
 
Bridge 
Forbids all STP BPDUs to go out the specific port and 
not to recognize incoming STP BPDUs the specific 
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. 
 
8.3.9.6 BPDU 
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.