近年來，針對有線環境中允許使用者移動之網路協定以行動網際網路協定（Mobile Internet Protocol）最為實用，而行動網際網路利用兩種方式來達到群播的功能，分別為遠端訂閱（remote subscription）和雙向轉傳（bi-directional tunneling）。在遠端訂閱中，雖然有著最佳的傳送路徑，但在漫遊中卻有封包遺失量大與花費時間在重建群播樹上的缺點。而雙向轉傳雖然在重建群播樹上花費時間較短以及漫遊時封包遺失的問題可以獲得解決，可是在傳送上卻使用了極差的繞送路徑來傳送封包並會有三角繞送的問題，在需要節省頻寬的群播服務中產生了相當沒有效率的缺點。
為了改善這些問題，本論文發展了一個能在行動網際網路中提供有效率且具可靠性之群播協定。除了增加繞送的效率外，重點放在減少達到可靠度所需要的封包數量，並使得支援行動網際網路之群播協定在路徑與時間上取得平衡。此具可靠性之群播協定依據遠端訂閱以遠端代理者加入群播的機制為基礎，在此機制上採用一個群播前送代理人（Multicast forwarding agent）來改善遠端訂閱群播樹重建的次數，以解決漫遊過程中產生的接收封包不同步（out-of-synch）的問題。此一特色能減少資料重複以避免頻寬浪費並擁有較佳的傳送路徑。此外由於使用階層式回復策略亦可改善回復要求封包的數量以避免擁塞。
在本論文中利用模擬，對此協定做了驗證，證明在傳送路徑方面能有效縮短使用雙向轉傳的路徑長度，且在使用較少的封包傳送數量下能提供可靠度，同時在不同網域漫遊時產生的封包遺失的現象亦可獲得改善。

Recently years, providing multicast services to hosts becomes popular and many multicast protocols have been proposed. Mobile IP uses two approaches for mobile multicasting, namely, remote subscription and bi-directional tunneling. Remote subscription enjoys efficient delivery, but suffers from serious packet loss and wastes a lot of time on reconstructing multicast tree during roaming. Bi-directional tunneling wastes less time on reconstructing multicast tree and is free from packet losses due to roaming; however, it suffers from inefficient delivery path and the triangular routing problem which results in inefficient routing on multicasting.
In order to diminish these drawbacks, this paper propose a new protocol to provide efficient and reliable multicast services for mobile IP networks. The new protocol improves the efficient of delivery with less number of packets for reliability. It can also get balance between the length of routing path and the time used to route. This reliable multicast routing protocol is derived from the use of the remote subscription and using MFA （multicast forwarding agent） to reduce the times of reconstructing the multicast tree. Multicast forwarding agent routes the missing datagrams caused by the out-of-synch problem to prevent roaming from packet loss and data duplication which may cause inefficient routing. Besides using the hierarchical routing recovery policy is for avoiding the ACK implosion.
The results of simulation show that this protocol has higher delivery efficiency in comparison with bi-direction tunneling and use less packets for routing which will provide more reliability and could be easier to recover from packet loss during roaming.

[1]Charles Perkins, ”IP Mobility Support” ,RFC-2002, Mobile IP Working Group, October1996.

[2]C. L. Williamson et al. "Performance Evaluation of the MoM Mobile Multicast Protocol," ACM/Baltzer Mobile Networks and Applications, v.3 no.2, pp 189-201, Aug. 1998

[3]W. Simpson, IP in IP Tunneling, RFC 1853, 1995

[4]Chunhung Richard Lin and Kemin Wang, "Mobile Multicast Support in IP Networks", IEICE Transactions on Communications, Febuary 2001.

[5]Jen-An Ke and Wanjiun Liao, "Reliable Mobile Multicast Protocol （RMMP）: A Reliable Multicast Protocol for Mobile Networks Using Mobile IP," in Proc. Wireless Communications and Networking Conference （WCNC） 2000, Chicago, Sept. 2000.

[6]Wanjiun Liao, Chien-An Ke, and Jiunn-Ru Lai, " Reliable Multicast with Host Mobility," Proc. of IEEE GlobeCom'00, November/December 2000.

[7]R. Droms, Dynamic host configuration protocol, RFC 1540, Buck-nell University （October 1993）.

[8] Chunhung Richard Lin and Kai-Min Wang, "Mobile Multicast Support in IP Networks," Proc. of IEEE INFOCOM'00, March 2000.

[9]C. Perkins, “IP encapsulation within IP” ,RFC 2003, May 1996.

[10]D. Johnson and C. Perkins, “Route optimization in Mobile IP”, in Internet Draft, Mobile IP Group, November 1996.

[11] Charles E.Perkins , Mobile IP “Design Principles and Practices “

[12] Hrishikesh Gossain, Siddesh Kamat and Dharma P. Agrawal, "A Framework for Handling Multicast Source Movement over Mobile IP,"Proc. of ICC'2002, April/May 2002.

[13]G. Xylonmenos and G. Polyzos. “IP Multicast for Mobile Hosts,” IEEE Communications Magazine, pp. 54-58, January 1997.

[14]V. Chidarmane and C. L. Williamson “Multicast Support for Mobile Host using Mobile IP: Design Issues and Proposed Architecture,” Mobile Networks and
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[15]Deering, S., “Host Extensions for IP Multicasting,” RFC 1112, August 1989.

[16]Fenner, W., Internet Group Management Protocol, Version 2, RFC 2236, November 1997.

[17]S. Deering, Internet Control Message Protocol （ICMP）RFC 1256, September 1991

[18] H. Gossain and D. P. Agrawal, “A Differential Service based approach to deliver multicast messages over mobile IP," VTC Spring 2001, May 6-9, 2001, Rodos Palace Hotel, Rhodes, Greece.

[19] P. Calhoun and C. E. Perkins, "Mobile IP Network Access Identifier Extension for IPv4," IETF RFC 2794, Mar. 2000.

[20] Tim G. Harrison, Carey L. Williamson, Wayne L. Mackrell, Richard B. Bunt: Mobile Multicast （MoM） Protocol: Multicast Support for Mobile Hosts. MOBICOM 1997: 151-160

[21] J. Postel, "Transmission Control Protocol, " Internet Request for Comments RFC 793, September 1981.

[22] E. Gustafsson, A. Jonsson, and C. E. Perkins, "Mobile IP Regional Registration," draft-ietf-mobileip-reg-tunnel-02.txt, Mar. 2000; work in progress.

[23] Omar, H.; Saadawi, T.; Lee, M.; ”Multicast with Reliable Delivery Support in the Regional Mobile-IP Environment”Computers and Communications, 2001. Proceedings. Sixth IEEE Symposium on , 2001 Page（s）: 466 –471

[24] A. G.Valko, "Cellular IP: A New Approach to Internet Host Mobility," Comp. Commun. Rev., vol. 29, no. 1, Jan. 1999, pp. 50–65.

[25] Hee-Sook Shin, Young-Joo Suh, and Syungog An, "Multicast Routing Protocol in Mobile Networks," Journal of KISS: Information Networking, vol.27, no.4, pp.418-428, Dec. 2000.