Bridge groups and BVIs are very hard for me to understand. There is no good explanation of these concepts on the web that I am able to find.
As far as I can tell, a bridge group is a logical device to hook (to bridge) a vlan to a wireless LAN. To connect the two, you put a vlan (say vlan 10) into bridge group 7 and then you put the radio interface of a wireless LAN into the same bridge group 7. The result of this is that the computers which communicate with the switch wirelessly are now part of (bridged to) vlan 10. You might consider a wireless LAN to be a vlan even though it never seems to be called a vlan. So when you bridge a wireless LAN and a vlan, you are building a layer 2 bridge between 2 vlans.
A BVI is apparently a way to assign an IP address to this new hybrid (wired and wireless) vlan 10. I guess to get out to the Internet from a computer that is communicating wirelessly to a switch, you have to have both the bridge group and the BVI.
If you don't hook the wireless computers to vlan 10 using the bridge group, then you won't have communication between the wired and wireless computers. And if you don't have the BVI, then there is no way to get out to the Internet because you won't have an IP address.
Back to bridge groups. Let's say you have Wanda using a computer connected wirelessly to a switch and Bob using a computer connected to the switch by cat 5 cable. If you do not combine Wanda's wireless LAN with Bob's vlan, then assume Wanda and Bob cannot communicate. Meaning that they can't ping each other. I assume after you put them both into a common bridge group that they CAN ping each other. I will have to try that experiment some time.
The following 3 commands are necessary, but I don't really understand them. irb is integrated routing and bridging. I guess "bridge 7 route ip" means that IP packets can be routed to bridge group 7.
bridge irb
bridge 7 protocol ieee
bridge 7 route ip
interface vlan 10
bridge-group 7
interface dot11radio0
bridge-group 7
interface BVI7
ip address 192.168.0.1
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