Abstract: The regional foreign agent Mobile-IP approach was introduced to reduce the frequency by which registration with the remotely located home agent is needed. Providing an efficient system that support IP multicast, in an environment where the multicast group members frequently change their locations, is a challenge for systems providing mobility support. In addition, sensitive applications require a reliable multicast service such that each intended receiver is guaranteed to receive a copy of each transmitted packet. In this work we will propose an architecture that supports IP multicast in an environment where mobility is supported using regional foreign agents. The proposed scheme takes advantage of the inherent characteristics of the local registration to enhance the efficiency of the multicast support. Performance aspects such as multicast datagram delay, delivery cost and robustness are analyzed. Simulation results are used to describe the performance under various conditions. In addition, the proposed approach will be extended to support reliable multicast. The proposed scheme tolerates the failure of regional foreign agents, and compensates for those datagrams undelivered due to such failures and for those due to the mobility of the receivers.