So the number of binding up messages between MN and CN will be decreased and the handover delay will be improved. Fast handover for hierarchical MIPv6 technology (FHMIPv6) integrates FMIPv6 and HMIPv6; arrange fast handover in hierarchical Mobile IPv6 mobility management and decreases the handover delay even more.By research of FHMIPv6, the procedure of duplicated address detection (DAD) badly decreases the performance of handover, so a new technology named multicast-fast handover for hierarchical MIPv6 (M-FHMIPv6) has been putted forward based on IPv6 multicast. When the mobile nodes has detected L2 trigger and knows that it will enter a new subnet, so it switches to multicast mode and a multicast group will be set up. CN, PAR and NAR will join it. CN becomes the multicast source and keep sends data packets to MN until the handover has been finished.The theoretical analysis shows that although M-FHMIPv6 needs to build multicast group in handover procedure, but can effectively reduce handover delay caused by DAD and information exchange. Finally, simulator in NS2 further proved that M-FHMIPv6 can reduce delay and smooth handover process, achieve the desired results.
