Customer has deployed Broadcast Multicast Optimization in this network. This article is to explain if that would hinder Airgroup deployment by any means.
The BCMC Optimization knob is used for controlled flooding of the outgoing broadcast/ multicast traffic. By default this option is disabled. One must enable this knob for controlled flooding of BCMC traffic, with following exceptions:
- All DHCP traffic will continue to be allowed
- ARP request packets will continue to be flooded
- mDNS multicast packets will be allowed
The BCMC knob is applied on a VLAN, and will control the BCMC traffic flooding on all VLAN member ports.
The AirGroup feature is enabled by default, and will send out limited required multicast mDNS packets, on need basis, bypassing the BCMC knob as listed above. The regular multicast mDNS traffic received by the mobility controller, gets terminated in the control plane, and is not transmitted out. This is independent of the BCMC knob status.
If a customer chooses to disable the AirGroup feature, the outgoing mDNS multicast traffic will meet the following treatment:
- If BCMC knob is disabled, all outgoing mDNS multicast traffic will be allowed
- If BCMC knob is enabled, all outgoing mDNS multicast traffic will continue to be allowed.
With the BCMC knob enabled and AirGroup feature disabled, if a customer chooses to drop the outgoing mDNS multicast traffic, it has to configure an ACL to block multicast mDNS traffic destined to udp port 5353.