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Cisco Catalyst Blade Switch 3130 for Dell Software Configuration Guide
OL-13270-01
Chapter19 Configuring Optional Spanning-Tree Features
Configuring Optional Spanning-Tree Features
The BPDU guard feature provides a secure response to invalid configurations because you must
manually put the port back in service. Use the BPDU guard feature in a service-provider ne twork to
prevent an access port from participating in the spanning tree.
Caution Configure Port Fast only on ports that connect to end stations; otherwise, an accidental topology loop
could cause a data packet loop and disrupt switch and network operation.
You also can use the spanning-tree bpduguard enable interface configuration command to enable
BPDU guard on any port without also enabling the Port Fast fe atur e. When the port receives a BPDU, it
is put it in the error-disabled state.
You can enable the BPDU guard feature if your switch is running PVST+, rapid PVST+, or MSTP.
Beginning in privileged EXEC mode, follow these steps to globally en able the BPDU g uard feature. This
procedure is optional.
To disable BPDU guard, use the no spanning-tree portfast bpduguard default global configuration
command.
You can override the setting of the no spanning-tre e portfast bpduguard default global configuration
command by using the spanning-tree bpduguard enable interface configuration command.
Enabling BPDU Filtering
When you globally enable BPDU filtering on Port Fast-enabled interfaces, it preven ts interf ac es that ar e
in a Port Fast-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. Y ou should globally en able BPDU filteri ng
on a switch so that hosts connected to these interfaces do not receive BPDUs. If a BPDU is received on
a Port Fast-enabled interface, the interface loses its Port Fast-operational status, and BPDU filtering is
disabled.
Caution Configure Port Fast only on interfaces that connect to end st at ions; o ther wis e, a n acc id ental to pology
loop could cause a data packet loop and disrupt switch and network operation.
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 spanning-tree portfast bpduguard default Globally enable BPDU guard.
By default, BPDU guard is disabled.
Step3 interface interface-id Specify the interface connected to an end station, and enter
interface configuration mode.
Step4 spanning-tree portfast Enable the Port Fast feature.
Step5 end Return to privileged EXEC mode.
Step6 show running-config Verify your entries.
Step7 copy running-config startup-config (Optional) Save your entries in the configuration file.