Processing Internet Group Management Protocol (IGMP) messages in which a response-mode determination process is facilitated after receiving an IGMP Membership Report designating a requested multipoint leaf connection, where in a proactive expedited leave process is performed in response to determining that implementation of the requested multipoint leaf connection is required and that required network resources are unavailable. A multicast leaf connection implementation process for implementing the requested multipoint leaf connection is performed in response to determining that required network resources are available.