Users demand not only seamless continuation but also high throughput of Internet access as they hop across different administrative domains and heterogeneous networks during an ongoing session. By extending the multiple care-of addresses registration based on Mobile IPv6, the proposed mechanism may provide seamless access with soft handoff notion as well as high throughput with automatically selecting the best link among multiple interfaces when the wireless channel continuously changes. Moreover, our mechanism can fit for any access technologies because only layer three modification and techniques (like Packet Pair) are required. The simulation result shows the proposed scheme outperforms the conventional Mobile IPv6 in both seamless continuation and throughput. This study also provides a further insight on the issues of multiple interfaces and heterogeneous networks, which can promote the technology of next generation wireless network. Index Terms -Mobile IPv6, multiple care-of addresses registration, soft handoff, multi-rate wireless network.