An efficient dynamic multicast agent approach for mobile IPv6 multicast

<draft-zhang-mipshop-multicast-dma-01.txt>

Hongke ZhangBo ShenBingyi ZhangBeijing Jiaotong University

Enhui LiuSpencer Dawkins

Huawei Technologies Co., Ltd.

Mobile nodes are different from fixed terminals for their roaming features. What address is used for MNs to join the multicast group membership? Home-Address or Care-of-Address?

One basic method is MIP-BT. Mobile nodes join the multicast group with their Home-Address and receive the multicast data from their home agent via Bidirectional Tunnels. [Disadvantages: triangle routing, long tunnels, large number of tunnels, tunnel congregating, packet latency… ]

Another basic method is MIP-RS. Mobile nodes join the multicast group with their Care-of-Address and receive the multicast data from their foreign agent via Remote Subscription. [Disadvantages: frequent rejoin/leave the multicast group due to CoA changes, the resulting frequent multicast tree restructuring, handover latency, packet loss… ]

Challenges to Mobile IPv6 Multicast

Mobile IPv6 Multicast with DMA

Concepts:

MSA -- Multicast Subnet Agent, which is the access router running multicast protocols in a subnet and forwarding the subscribed multicast data to the MN that visits the subnet.

DMA -- Dynamic Multicast Agent, which is the current MSA or one of the previous MSAs of the MN acting as the leaf router in a multicast delivery tree the MN subscribed and forwarding the subscribed multicast data to the MN through its current MSA.

Mobile IPv6 Multicast with DMA

Internet

MSA2

Multicast Source

MN_A

DMA1(MSA1)

MN MNMN_A

MNMN_A

DMA2(MSA3)

MN moves from DMA1 to MSA2, (Supposing MN within roaming distance)MN moves from MSA2 to DMA2, (Supposing MN beyond roaming distance)

Mobile IPv6 Multicast with DMA

Main Idea: The MN joins the multicast group membership with its care of address.

When a MN first subscribes a multicast group G, its current MSA becomes its initial DMA.

Within an acceptable roaming distance, the DMA of a MN will not change although its visited MSA changes if its visited MSA doesn't yet have the group G membership in the subnet.

Beyond this acceptable roaming distance, the MN's DMA will be switched to the new MSA that the MN currently is visiting.

When the MN's current MSA is different from its DMA, its current MSA receives the group G multicast data from its DMA via a short tunnel, and then forwards the multicast data to the MN.

Mobile IPv6 Multicast with DMA

HA Multicast Routing ProtocolMLD ReportMulticast Traffic

MSA

Source

DMA

MN

PIM Join Msg

Multicast Traffic

When the MN's current MSA is different from its DMA, ……

DMA switch decision-making algorithm

Main Principle:

There shouldn’t be any DMA switch for an MN within an acceptable roaming distance if the MN’s visited MSA doesn’t yet have the group G membership in the subnet.

Decision-making Algorithm in DMA:

Algorithm is base on movement and distance. It could be simple or precise.

DMA maintains a table to record the MN’s recent attachment history, which is used for decision making.

In the document we just provide a simple algorithm via checking the path increment of the recently joined MSA. It’s distance-based.

Conclusion

The MN joins the multicast group membership with its care of address.

One purpose is to avoid the disadvantage of MIP-BT method: such as triangle routing, long tunnels, large number of tunnels, tunnel congregating, packet latency…

The other purpose is to avoid the disadvantage of MIP-RS method: such as frequent rejoin/leave the multicast group due to CoA changes, the resulting frequent multicast tree restructuring, handover latency, packet loss…

Questions about the draft in the mail list

(1) What the difference is between your draft with other similar drafts?

There are three main different points: (a) There is a algorithm in our draft. The dynamic and flexible DMA can be selected through this algorithm.(b) They are different in how to switch multicast agent. One method is to select some multicast agent before MN moving. Our method is to select some MSA before MN moving. However the MSA not always become a multicast agent.(c) In our draft, MN do not attend the selection of multicast agent.

(2) In your draft, how do you compute the threshold?

The computation of the threshold can be simple or precise. In the version 00, the threshold is computed based on the distance of MN movement.

Thanks for your attention and Suggestion!

<draft-zhang-mipshop-multicast-dma-01.txt>

Contact info: Spencer Dawkins <sdawkins@futurewei.com> Hong-Ke Zhang <hkzhang@center.njtu.edu.cn>