This article applies to Aruba Mobility Controllers running ArubaOS version 18.104.22.168.
There are a couple of broadcast controls on the controller which, depending upon how they are configured, will affect AirGroup functionality on the controller.
Broadcast-Multicast optimization is a VLAN-specific feature within the Aruba controller which when enabled drops most broadcast or multicast traffic on the VLAN member ports, preventing that traffic from flooding the VLAN and thus conserve bandwidth.
Drop Broadcast and Multicast (or broadcast-filter-all) is a VAP-based feature which when enabled drops broadcast/multicast traffic egressing the VAP into the air.
When AirGroup is enabled on a controller, it automatically creates exceptions for mDNS traffic to bypass the above knobs.
In the Integrated deployment model, enabling or disabling the above controls on the AirGroup controller has no impact on AirGroup functionality. It is however, recommended that both features be enabled to minimize broadcast/multicast traffic on the user VLAN and in the air.
In the overlay model, however, the access controller needs to forward mDNS (i.e., multicast) packets to the voverlay controller (using the mDNS redirect ACL). Enabling BC-MC optimization on the access controller will cause it to drop broadcast/multicast packets before any ACL can be applied to them. This will cause AirGroup to break.
VAP-based broadcast controls on the access controller can be enabled but doing so will prevent the overlay controller from pro-actively learning new Airgroup services on the WLAN. AirGroup services will only be learnt when AirGroup servers send out unsolicited mDNS responses.