16-8
Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
78-17058-01
Chapter 16 Configuring Optional Spanning-Tree Features
Configuring Optional Spanning-Tree Features
You can also use the spanning-tree bpdufilter enable interface configuration command to enable
BPDU filtering on any NNI without also enabling the Port Fast feature. This command prevents the NNI
from sending or receiving BPDUs.
Caution Enabling BPDU filtering on an NNI is the same as disabling spanning tree on it and can result in
spanning-tree loops.
You can enable the BPDU filtering feature if your switch is running PVST+, rapid PVST+, or MSTP.
Beginning in privileged EXEC mode, follow these steps to globally enable the BPDU filtering feature.
This procedure is optional.
To disable BPDU filtering, use the no spanning-tree portfast bpdufilter default global configuration
command.
You can override the setting of the no spanning-tree portfast bpdufilter default global configuration
command by using the spanning-tree bpdufilter enable interface configuration command on an NNI.
Enabling EtherChannel Guard
You can enable EtherChannel guard to detect an EtherChannel misconfiguration if your switch is
running PVST+, rapid PVST+, or MSTP.
Beginning in privileged EXEC mode, follow these steps to enable EtherChannel guard. This procedure
is optional.
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
spanning-tree portfast bpdufilter default Globally enable BPDU filtering. (By default, BPDU filtering is
disabled.)
Note Globally enabling BPDU filtering enables it only on
NNIs; the command has no effect on UNIs.
Step 3
interface interface-id Specify the interface connected to an end station, and enter
interface configuration mode. If the interface is not an NNI, you
must enter the port-type nni interface configuration command
before enabling Port Fast.
Step 4
spanning-tree portfast Enable the Port Fast feature.
Step 5
end Return to privileged EXEC mode.
Step 6
show running-config Verify your entries.
Step 7
copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
spanning-tree etherchannel guard misconfig Enable EtherChannel guard.
Step 3
end Return to privileged EXEC mode.
