JOURNAL OF INFORMATION SCIENCE AND ENGINEERING 20, 1109-1124 (2004) 1109 A Multicast Routing Protocol with Dynamic Tree Adjustment for Mobile IPv6 * RUAY-SHIUNG CHANG AND YUN-SHENG YEN Department of Computer Science and Information Engineering National Dong Hwa University Hualien, 974 Taiwan E-mail: {rschang, m89021509}@mail.ndhu.edu.tw TCP/IP is currently the standard network protocol for wired Internet. To make all Internet services available to all mobile users, a Mobile IP is proposed. Another impor- tant development for TCP/IP is the evolution to the next generation Internet, the protocol for which is called IPv6. Whether using IPv4 or IPv6, situations arise in some Internet applications where a piece of data needs to be sent to multiple recipients, a process called multicasting. In this paper, we study the multicasting routing problem based on Mobile IPv6. In multicasting, the mobility of a sender may lead to serious problems. When the sender moves, the full delivery tree may fail so that multicast datagrams cannot be for- warded to all receivers. In this paper, we propose a Reverse Traffic Interface (RTI) mechanism to preserve the integrity of the multicast tree. In this mechanism, we will use a Backward-Forced Path (BFP) to regenerate a new tree without rerouting. It can ensure multicast datagrams are sent to all reachable destinations without interruption. In addi- tion, we show that a slight modification of the DVMRP (Distance Vector Multicast Routing Protocol), called DVMRPv6, can be used in Mobile IPv6 to support our mecha- nism. Finally, we use a total tree cost measure to estimate and evaluate our scheme. We also implement simulations to demonstrate its effectiveness. The results show that our proposal makes multicasting on mobiles network simpler, more efficient, and more reli- able. Keywords: TCP/IP, IPv6, mobile IPv6, multicasting, DVMRP 1. INTRODUCTION The Internet continues to expand and to increase its applications (e.g., Multimedia on Demand, Video Conferencing, Distance Learning, On-line Gaming, Home Shopping, etc.). Likewise, the technological development of integrated circuits has become more elaborate and miniaturized. Hence, some delicate appliances (e.g., Notebook, PDA, lap- top, palmtop, PocketPC) are also becoming more light-weight and handier for people to use. As wireless technology develops, humans devise increasingly sophisticated methods of communication. The invention of mobility supporting networks is an important ad- vance. It permits direct communication by radio waves between people who are far away from each other. Wireless networks become a reality and mobile computing and commu- Received March 30, 2004; accepted June 30, 2004. Communicated by Don-Lin Yang. * This research is supported by ROC NSC under contract number 91-2219-E-259-003.