Subject: [Mipshop] Re:draft-zhang-mipshop-multicast-dma-00.txt

From: "[email-masked]" <[email-masked]>
Date: Thu, 2 Jun 2005 13:21:42 +0800

mipshop
Hi,everyone:
I am Hong-Ke Zhang and glad to contribute our draft to get your comments. First, I give an introduction as follows:
  IPv6 will replace IPv4 gradually in next generation network. Along with the development of the wireless IP technologies, more and more people have the chance to use wireless equipment accessing network. They will likeing this method gradually and being in the habit of accessing wireless network. Now there are more than 200 millions of mobile terminal users such as mobile phone users in China. Multicast is also a hot point and many research have been studyed in it. There have been many multicast route protocols, such as DVMRP, MOSPF, MSDP, BGMP and PIM-SSM and so on. Unfortunately they are not suit to mobility wireleless network. Supporting the mobility and multicast will becomes the inevitable function in next generation network. So how to support multicast in mobile IPv6 network is a inevitable question. The research in mobile multicast is important and necessary. 
  However we face the challenge to combine mobile IP with multicast now. There are many difficulties during the researches. First the existing IP multicast protocols can’t satisfy the needs of node for mobility. Second the handoff time of mobile node and the delay used in rejoining in multicast group is too long , so it can’t meet the requirement of QoS yet. Third the reconstruction of multicast tree caused by the MN handoff in the subnet frequently burden the network load. Fourth the existing mobile IP multicast protocols have the problems of triangle route and tunnel congregation. Above all the optimization design for mobile multicast route is very important.
  For conquerving the above problems, we propose a DMA (Dynamic Multicast Agent) approach in our draft. The DMA approach is based on the porposed MIP-BT (Mobile IP – Bidirectional tunnel) and MIP-RS (Mobile IP – Remote Subscription). The MIP-BT use a bi-directional tunnel between a MN with its HA to support mulcast in mobile network. The MIP-RS using a multicast router in a foreign subnet being visited to support multicast in mobile network. These two methods can remain the multicast communications when MNs move, but there are some disadvantages about them. To MIP-BT, the triangle route problem will add the network cost and the tunnel congreation problem can not be solved yet. To MIP-RS, when the handoff occures frequently, the rejoin of a MN and the reconstruction of multicast tree will cause too long delay and too much cost.
The DMA conquers the problems in MIP-BT and MIP-RS. The DMA approach includes three concepts of MSA (Multicast subnet Agent), DMA and Tunnel State. The approach is a combination of MIP-BT and MIP-RS, and it is also a hybrid solution of movement based method and distance based method. Such a configuration allows MNs to optimize multicast routes, and meanwhile reduce the number of handoffs by selecting new multicast agents dynamically. In addition to weakening the triangle route problem and diminishing the influence of handoff to multicast
A throughness flow chart of DMA approach, the operation of MSA and dynamic multicast agent selection all have been given. The mathmatics analysis and simulation in NS are also completed. The results in simulation denote that DMA approach can effectively reduces the reconstructing of multicast tree and the multicast packages can be forwarded through optimal path.   
  The DMA approach can improving the network performance effectively and adapt to the mobile IPv6 multicast.
Above all, I hope you give your helps and comments.

Best regards with many thanks 
Hong-Ke Zhang 

　　　　　　　　HKzhang
　　　　　　　　[email-masked]
　　　　　　　　　　2005-06-02
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