The objective of this Recommendation is to describe the mobility management capabilities to support Internet Protocol (IP) multicast-based services in next generation networks (NGNs). Specifically, this Recommendation pursues network-based mobile multicast support wherein multicast is handled without the involvement of the user equipment during handover. This Recommendation identifies design considerations, functional architecture, and information flows for supporting network-based mobile multicast services in NGNs. This Recommendation builds on the general mobility management functionalities described in [ITU-T Q.1707] and multicast functionalities described in [ITU-T Y.2017].