A company has three Cisco WLCs that are joined as a mobility group.

When Cisco WLCs are configured to use multicast for mobility group communications, all WLCs participating in the same mobility group must be configured with an identical multicast group IP address. The mobility multicast mode allows a WLC to send a single multicast frame received simultaneously by all other WLCs in the group, rather than sending individual unicast copies to each peer. For this to function correctly, every WLC in the group must join the same IP multicast group address, and the underlying network infrastructure must be configured to support IP multicast routing or IGMP snooping for that specific group address. If any WLC is configured with a different multicast IP address, it will join a different multicast group and will not receive mobility messages from the other WLCs, effectively isolating it from the group ' s communication plane. Service port IP addresses (Option A) are unique per controller. Interface IDs (Option B) are locally significant identifiers. Management IP addresses (Option C) are unique per WLC and identify each peer in unicast configurations. Reference: WLSD Study Guide — Mobility Group Configuration, Multicast Mobility Messaging, WLC Peer Communication.