Cisco Wireless: Bridge Groups
In general, bridge groups create segmented switching domains. Traffic is confined to hosts within each bridge group, but not between the bridge groups. The switch forwards traffic only among the hosts that make up the bridge group, which restricts broadcast and multicast traffic (flooding) to only those hosts. Bridge groups relieve network congestion and provide additional network security when they segment traffic to certain areas of the network.
In a wireless network, bridge groups are configured on the wireless access points and bridges in order for the data traffic of a VLAN to be transmitted from wireless media to the wired side and vice versa.
Configure the radio interface and the Fast Ethernet interface of the wireless device to be in the same bridge group. This creates a path between these two different interfaces, and they are in the same VLAN for tagging purposes. As a result, the data transmitted from the wireless side through the radio interface is transmitted to the Ethernet interface to which the wired network is connected and vice versa. In other words, radio and Ethernet interfaces that belong to the same bridge group actually bridge the data between them.
In an access point/bridge, you need to have one bridge group per VLAN so that traffic can pass from the wire to the wireless and vice versa. The more VLAN you have that need to pass traffic across the wireless, the more bridge groups that are needed.
