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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter 36 Configuring Fallback Bridging
Configuring Fallback Bridging
This example shows how to create bridge group 10, to specify that the VLAN-bridge STP runs in the
bridge group, to define an interface as a routed port, and to assign the interface to the bridge group:
Switch(config)# bridge 10 protocol vlan-bridge
Switch(config)# interface gigabitethernet0/1
Switch(config-if)# no switchport
Switch(config-if)# no shutdown
Switch(config-if)# bridge-group 10
This example shows how to create bridge group 10 and to specify that the VLAN-bridge STP runs in the
bridge group. It defines an interface as an SVI and assigns this interface to VLAN 2 and to the bridge
group:
Switch(config)# bridge 10 protocol vlan-bridge
Switch(config)# vlan 2
Switch(config-vlan)# exit
Switch(config)# interface vlan2
Switch(config-if)# exit
Switch(config)# interface gigabitethernet0/2
Switch(config-if)# switchport mode access
Switch(config-if)# switchport access vlan 2
Switch(config-if)# no switchport
Switch(config-if)# no shutdown
Switch(config-if)# bridge-group 10
Preventing the Forwarding of Dynamically Learned Stations
By default, the switch forwards any frames for stations that it has dynamically learned. By disabling this
activity, the switch only forwards frames whose addresses have been statically configured into the
forwarding cache.
Beginning in privileged EXEC mode, follow these steps to prevent the switch from forwarding frames
for stations that it has dynamically learned:
To cause the switch to forward frames to stations that it has dynamically learned, use the bridge
bridge-group acquire global configuration command.
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
no bridge bridge-group acquire
Enable the switch to stop forwarding any frames for stations that it has
dynamically learned through the discovery process and to limit frame
forwarding to statically configured stations.
The switch filters all frames except those whose destined-to addresses
have been statically configured into the forwarding cache. To configure
a static address, use the bridge bridge-group address mac-address
{forward | discard} global configuration command.
For bridge-group, specify the bridge group number. The range is 1
to 255.
Step 3
end
Return to privileged EXEC mode.
Step 4
show running-config
Verify your entry.
Step 5
copy running-config startup-config
(Optional) Save your entry in the configuration file.