Multicast support for mobile IP using a modified IGMP

To handle connectivity of mobile hosts to the Internet, the mobile Internet Protocol (IP) has been proposed. Mobile IP functions by assigning a home agent and a foreign agent and creating a tunnel between the two. While this protocol works satisfactorily for point-to-point IP communication between mobile hosts, it results in avoidable overheads for multicast communication. We propose modifications to the Internet Group Management Protocol (IGMP) for enhancing support to multicast communication in a mobile environment. Because of the large overhead involved in IP tunneling for the multicast communication, we propose eliminating tunneling. Instead, we enhance the IGMP to manage the memberships of various multicast groups for mobile hosts more effectively. As currently implemented, the IGMP handles multicast groups one at a time. When a mobile host moves to a new point of IP attachment, it needs to leave and rejoin many groups. We propose a modified IGMP that allows a host to leave or join many multicast groups simultaneously.