Use a Bridge Virtual Interface when you want to have multiple router interfaces act as members of a single Ethernet collision domain, or bridge two separate network segments together. Lots of wireless bridges use this function to attach their wireless clients to a local Ethernet. Start by defining the bridge group:
router(config)#bridge 202 protocol ieee
router(config)#bridge 202 route ip
Then put some interfaces into that group:
router(config)#int faste31
router(config-if)#bridge-group 202
router(config-if)#int faste32
router(config-if)#bridge-group 202
router(config-if)#int faste33
Then, create the BVI interface:
router(config-if)#int bvi202
router(config-if)#desc new server cluster
router(config-if)#ip addr 198.22.62.65 255.255.255.240
Your BVI interface should be up, and all these formerly “router” ports should now be a transparent bridge.
(Why am I using BVI instead of VLAN on a bunch of Ethernet ports? This particular switch is configured as a router, and it really wants to treat all the interfaces as router interfaces. It insists it doesn’t know how to configure a VLAN. I’m certain that Cisco has a reason for this, but their explanation might put me off my feed.)