Multimob Hong-Ke Zhang
Internet Draft Jian-Feng Guan
Expires: March 2009 Hua-Chun Zhou
Zhi-Wei Yan
Beijing Jiao Tong University
September 30, 2008
MLD Source Address Selection for Mobile Multicast
draft-zhang-multimob-mldsas-mmcast-00.txt
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Abstract
With the development of wireless and mobile technologies, mobile
multicast becomes a research hotspot. However, the current multicast
routing protocols can not provide the mobile multicast services. To
support the mobile multicast, the related multicast specifications
need to be extended. In this memo, we focus on the group membership
management protocol and define the new source address selection
policy for mobile multicast.
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Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [1].
Table of Contents
1. Introduction.................................................2
2. Terminology..................................................3
3. Justification................................................3
4. Source Address Selection for Mobile Multicast................3
5. Security Considerations......................................4
6. Acknowledgments..............................................4
7. References...................................................5
7.1. Normative References....................................5
7.2. Informative References..................................5
Author's Addresses..............................................6
Intellectual Property Statement.................................6
Copyright Statement.............................................7
Acknowledgment..................................................7
1. Introduction
MLD is a subset of ICMPv6 and the message types in MLDv1 [3] and
MLDv2 [4] are 130, 131, 132 and 143. All the MLD messages use the
link-local address as the source address, and set the hop limit to be
1. Besides, to force the IPv6 routers on that link to check the MLD
messages, all the MLD messages are encapsulated in the hop-by-hop
option with router alert option [5].
MLD is an asymmetric protocol which consists of the router function
and the host function. The router function is used to set up the
multicast states for subscribers, while the host function is used by
subscribers to send the multicast join and leave messages, and to
respond to periodic query messages.
However, the current MLD specifications are designed to maintain the
dynamic group membership for the fixed nodes. If the MLD protocol is
directly used in mobile multicast services, it may cause a long
multicast service disruption. According to the MLD specifications,
this disruption may be 67 seconds even without the link layer
handover and IP layer handover delay [8]. To improve the performance
of mobile multicast, some mobile multicast management protocol
mechanism has been proposed to manage the mobile subscribers. H. Liu
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and H. Asaeda [9] discussed the requirements about the deployment of
IGMP/MLD protocols for mobile multicast services. Besides, H. Asaeda
and T. C. Schmidt [10] modified the IGMP/MLD and introduced an
optional Listener Hold function to support the mobile hosts. Recently,
Guan et al. [11] proposed the extended MLD protocol to provide the
mobile multicast management for mobile subscribers. However, using
the MLD protocols as the multicast membership management in mobile
environments conflicts with the source address selection policy in
MIPv6 [6]. The MLD specifications mandate the use of a link-local
IPv6 source address or the unspecified address (::) [7] for the MLD
message. However, the MIPv6 suggests that the mobile node should use
the HoA when mobile node transmits the multicast packets through the
bi-directional tunnel, and uses the CoA when transmit the multicast
packets through the current foreign networks.
This memo will extend the IPv6 source address selection rules for use
with MLD protocols in mobile multicast services.
2. Terminology
The terminology used in this memo is already defined in MLDv1 [3] and
MLDv2 [4].
3. Justification
The MLD specifications require that all MLD messages be sent with a
valid link-local IPv6 source address. This design principle can
restrict group management messages in local link to prevent the
diffusion of group membership, which is benefit to reduce the
redundant information in the networks. However, it is unable to
provide the multicast management for mobile subscribers.
To provide the mobile multicast services for mobile subscribers, the
MLD protocols need some extensions to manage the mobile multicast
states such as the multi-hop extensions in [11]. The foundational
problem is how to set up and maintain the multicast states for mobile
subscribers. As discussed above, using the traditional MLD
specifications will result in a long disruption time and conflict
with the mobility specifications.
This memo tries to solve these problems by extending a new policy
about the source address selection.
4. Source Address Selection for Mobile Multicast
To mark the multicast states for mobile subscribers, MLD Report and
Done message SHOULD be sent with a valid global unicast IPv6 address
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as the IPv6 source address. As for the MLD Report message, some
extensions SHOULD be added to carry the location information,
Identifier information and group information of mobile subscribers
according to [11].
Routers receiving an MLD Report or Done message with the global IPv6
address as the IPv6 source address MUST perform the extended MLD
function shown in [11].
The extension of MLD source address selection is used to distinguish
the fixed node and mobile node, and provides the necessary
information for mobile subscribers.
5. Security Considerations
The related security issues are discussed in MLDv1 [3] and MLDv2 [4].
6. Acknowledgments
The authors would like to thank Si-Dong Zhang, Ya-juan Qin, Hongbin
Luo (BJTU NGIRC) for their valuable comments and suggestions on this
memo.
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7. References
7.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Crocker, D. and Overell, P.(Editors), "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, Internet Mail Consortium and
Demon Internet Ltd., November 1997.
[3] S. Deering, W. Fenner, B. Haberman, "Multicast Listener
Discovery (MLD) for IPv6", IETF RFC 2710, 1999.
[4] R. Vida and L. Costa, "Multicast Listener Discovery Version 2
(MLDv2) for IPv6", IETF RFC 3810, 2004.
[5] C. Partridge, A. Jackson, "IPv6 Router Alert Option", IETF RFC
2711, 1999.
[6] D. Johnson, C. Perkins, J. Arkko, "Mobility Support in IPv6",
IETF 3775, 2004.
[7] B. Haberman, "Source Address Selection for the Multicast
Listener Discovery (MLD) Protocol", IETF 3590, 2003.
7.2. Informative References
[8] Wu Qian, "Studies on IP Multicast in Mobile Internet" [Ph.D
Thesis], Beijing: Tsinghua University, 2006 (in Chinese with
English abstract).
[9] H. Liu and H. Asaeda, "Mobile Multicast Requirements on
IGMP/MLD Protocols", draft-liu-multimob-igmp-mld-mobility-req-
00, November, 2007.
[10] H. Asaeda and T. C. Hamburg, "IGMP and MLD Extensions for
Mobile Hosts and Routers", draft-asaeda-multimob-igmp-mld-
mobility-extensions-01, July, 2008.
[11] Jian-feng Guan, Hua-chun zhou, Hong-ke Zhang et al., "MLD
Extensions to Support the Mobile Multicast Group management",
draft-zhang-multimob-mld-mmcast-00.txt, July, 2008.
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Author's Addresses
Hong-ke Zhang, Jian-feng Guan, Hua-chun Zhou, Zhi-wei Yan
Next Generation Internet Research Center (NGIRC), Beijing JiaoTong
University
Beijing, China, 100044
Phone: +86 10 51685677
Email: hkzhang@bjtu.edu.cn
guanjian863@163.com
hchzhou@bjtu.edu.cn
06120232@bjtu.edu.cn
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