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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter26 Configuring Fallback Bridging
Configuring Fallback Bridging
Creating a Bridge Group
To configure fallback bridging for a set of SVIs or routed ports, these inte rf ace s m ust b e assig ned t o
bridge groups. All interfaces in the same group belong to the same b ridg e dom ai n. E a ch SV I or ro ut ed
port can be assigned to only one bridge group. A maximum of 31 bridge groups can be configured on
the switch.
Note The protected port feature is not compatible with fallback bridging . Whe n fallba ck bridg ing is
enabled, it is possible for packets to be forwarded from one protected port on a switch to anot her
protected port on the same switch if the ports are in different VLANs.
Beginning in privileged EXEC mode, follow these steps to create a bridge group and assign an interface
to it:
To remove a bridge group, use the no bridge bridge-group protocol vlan-bridge global configuration
command. To remove an interface from a bridge group, use the no bridge-group bridge-group interface
configuration command.
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 bridge bridge-group protocol
vlan-bridge Assign a bridge group number, and specify the VLAN-bridge
spanning-tree protocol to run in the bridge group. The ibm and dec
keywords are not supported.
For bridge-group, specify the bridge group number. The range is 1
to 255. You can create up to 31 bridge groups.
Frames are bridged only among interfaces in the same group.
Step3 interface interface-id Enter interface configuration mode, and specify the interface on which
you want to assign the bridge group.
The specified interface must be one of these:
•A routed port: a physical port that you have configured as a Layer 3
port by entering the no switchport interface configuration
command.
•An SVI: a VLAN interface that you created by using the interface
vlan vlan-id global configuration command.
These ports must have IP addresses assigned to them. For more
information, see the “Configuring Layer 3 Interfaces” section on
page8-22.
Step4 bridge-group bridge-group Assign the interface to the bridge group created in Step 2.
By default, the interface is not assigned to any bridge group. An
interface can be assigned to only one bridge group.
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.