MultiMob Working Group Dirk v. Hugo Internet Draft Deutsche Telekom Laboratories Intended Status: Informational Expires: April 22, 2010 October 19, 2009 Evaluation of further issues on Multicast Mobility: Potential future work for WG MultiMob Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 19, 2010. Copyright Notice Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. von Hugo, et al. Expires - April 2010 [Page 1] multimob-future-work October 2009 Abstract This document discusses potential future extensions on the current work plan of recently approved WG MultiMob (Multicast Mobility). MultiMob charter explicitly states that scope of work will be limited to mobility protocols Proxy Mobile IPv6, and multicast group management in terms of IGMPv3/MLDv2 protocols. Furthermore only listener mobility will be dealt with and any modification to these existing protocols and to multicast routing protocols are out of scope. From an operational point of view, however, though such a basic solution is essential, there challenges with efficient resource utilization and user perceived service quality still persist. As these issues may prevent large scale deployments of mobile multicast applications this document attempts to identify topics for future extension of work for WG MultiMob such as o modifying base PMIPv6 and MLD/IGMP for optimal multicast support o extending to and modifying of MIPv4/v6 and DSMIP o sender (source) mobility o consideration of Handover optimization o multiple flows o multi-hop transmission o any other different issues Intention of this document is to start and prepare for discussion on potential re-chartering after scheduled work. Introduction Recently chartered WG MultiMob focusses on documentation of proper configuaration and usage of existing (specified standard) protocols within both mobility and multicast related areas to enable and support mobility for multicast services and vice versa. Although the final recommendation is not yet available it is expected that such a solution following either the employed remote subscription aproach or a traditional bidirectional tunneling will not be resource efficient nor grant the service quality expected by the end user. von Hugo, et al. Expires - April 2010 [Page 2] multimob-future-work October 2009 Such a solution would resolve the problem to ensure multicast reception in PMIPv6-enabled [1] networks without appropriate multicast support. However it would neither automatically minimize multicast forwarding delay to provide seamless and fast handovers for real-time services nor minimize packet loss and reordering that result from multicast handover management as stated in [6]. Also Route Optimization is out of scope of the basic solution - an issue for reducing amount of transport resource usage and transmission delay. Thus possible enhancements and issues for solutions beyond a basic solution are described to enable current PMIP6 protocols to fully support efficient mobile multicast services. Such extensions may include protocol modifications for both mobility and multicast related protocols to achieve optimizations for resource efficient and performance increasing multimob approaches. The document includes the case of mobile multicast senders using Any Source Multicast (ASM) and Source Specific Multicast (SSM). +------+ +------+ | MN | =====> | MN | +------+ +------+ | . | . +-------+ +-------+ | MAG 1 | | MAG 2 | +-------+ +-------+ | | *** *** *** *** * ** ** ** * * * * Internet Subnet * * * * ** ** ** * *** *** *** *** | | +-------+ +-------+ | LMA 1 | | LMA 2 | +-------+ +-------+ | | *** *** *** *** * ** ** ** * * * * Fixed Internet * * * * ** ** ** * *** *** *** *** | +------+ | CN | +------+ Figure 1: MultiMob Scenario for chartered PMIP6 issue von Hugo, et al. Expires - April 2010 [Page 3] multimob-future-work October 2009 These issues of an extended optimiyed multicast mobility solution are sketched in Fig. 2: +------+ +------+ +------+ | MN | =====> | MN | ====> | MN | +------+ +------+ +------+ | . . | . . | . . +-------+ +-------+ +-------+ +-------+ | MAG 1 | | MAG 2 | | AR 1 | | AR 2 | +-------+ +-------+ +-------+ +-------+ \ / | | *** *** *** *** *** *** *** *** * ** *** ** * * ** *** ** * * * * * * Internet Subnet 1 * * Internet Subnet 2 * * * * * * ** *** ** * * ** *** ** * *** *** *** *** *** *** *** *** | | | +-------+ +-------+ | | LMA 1 | | LMA 2 | / +-------+ +-------+ / \ | / *** *** *** *** / *** *** *** *** * ** ** ** * / * ** *** ** * * * * * * Fixed Internet * * Internet Subnet 3 * * *_____* * * ** ** ** * * ** *** ** * *** *** *** *** *** .*** *** *** | . +-------+ +-------+ | CN | ====> | CN | +-------+ +-------+ Figure 2: MultiMob scenario for extended MultiMob issues In summary additional to a 'Single hop, link, flow' Proxy MIP mobility for listening MNs as shown in Fig. 1 the future work will extend the scenario to 'Multi-hop, -homed, -flow' client mobility (see Fig. 2). Potential extension of the basic solution could cover issues as o Modifation of base PMIPv6 and MLD/IGMP for optimal multicast support o Extension to and modifying of MIPv4/v6 and DSMIP von Hugo, et al. Expires - April 2010 [Page 4] multimob-future-work October 2009 o Consideration of sender (source) mobility o consideration of Handover optimization o Support of multiple flows o Multi-hop transmission o any other different issues 2. Problem Description The general issues if multicast mobility are extensively discussed and described in [6]. To reduce the complexity of the pleothera of requirements listed in [6] this document tries to propose lightweight solutions for multicast mobility which allow for easy deployment within realistic scenarios and architectures, and which build directly on basic MultiMob solution to be provided as a first outcome of MultiMob WG as e.g. proposal [7], [8], or [9]. 3. Issues for Modification of Future Multicast Mobility Protocols 3.1 Modification of base PMIPv6 and MLD/IGMP for optimal multicast support 3.1.1 Modification of PMIPv6 Solutions proposed within this section are either agent-based, rely on additional encapsulation or may be of a hybrid approach. Since other functional enhancements of PMIPv6 are currently under way in WG NETEXT both the impact of new features on Mobile Multicast as well as a potential Multicast-initiated proposal for PMIPv6 modification have to be considered in a continuous exchange process between both WGs. 3.1.2 Modification of MLD/IGMP Potential approaches for enhancement of group management as specified e.g. by MLDv2 [2] include default timer value modification, specific query message introduction, and standard (query) reaction suppression, beside introducing multicast router attendance control in terms of e.g. specification of a Listener Hold message. 3.2 Extension to and modifying of MIPv4/v6 and DSMIP Operational interest clearly focusses on network-based mobility approaches, but in the framework of multiple technologies serving a mobile user there will be demand to include also other non-PMIPv6 von Hugo, et al. Expires - April 2010 [Page 5] multimob-future-work October 2009 based specifications. This section addresses the compatibility of PMIPv6-based multicast solutions with MIPv6 [5], i.e. handover between network-based and client mobility support as well as interoperabiliy between IPv4 and IPv6 mechanisms (e.g. FA handling, IPv4/v4-tunneling) with mobile multicast. DSMIP (RFC 5454, [3]) deals with multicast group membership control messages such as MLD or MLDv2 [2], but does not specify how to achieve group management and data forwarding unless the Home Agent (HA) is a fully functional IPv6 multicast router. 3.3 Consideration of sender (source) mobility We see future demand for such a feature in terms of applications such as 'Push to talk over wireless technologies' (packet based P2MP group voice) like 3GPP or WiMAX, 'Multi-party mobile audio/video conferencing', 'mobile multi-player gaming' etc, where due to real-time constraints a solution based on a central server might add too much delay. According to [6] generally (i.e. for ASM) a mobile multicast source must provide address transparency at Routing - for Reverse Path Forwarding (RPF) checks - as well as on Transport layer - to coincide with packet source address at receiver side. Further issues are temporal handover constraints, possible packet loss and multicast scoping, and enhanced complexity of inter-domain multicasting. Additional challenges arise for SSM (Source Specific Multicast) due to the principle of multicast decoupling between sender and receivers. 3.4 Consideration of Handover optimization This work item would deal with reduction of delay, packet loss, and packet reordering effort. In case these degradations are induced due to terminal movement it will be discussed how to make use of MIPSHOP approaches such as HMIP, FMIP etc. (predominantly focussing on intra-technology handover). Reusing multicast specific protocol extensions exceeding IGMP/MLD modifications shall further decrease the impact of group management induced delay. 3.5 Support of multiple flows Considering a per-flow handover for parallel multicast sessions allows to treat different services requirements and labels of flows independently. This would improve user perceived service performance as well as allow for more efficient usage of network resources because of the enabled flexibility. von Hugo, et al. Expires - April 2010 [Page 6] multimob-future-work October 2009 3.6 Multi-hop transmission This scenario adds another level of complexity to Multicast Mobility and is of interest e.g. in nested NEMO (Network Mobility, RFC 3963 [4]) scenarios, for MANETs (Mobile Adhoc NETworks) where also mechanisms for multicast forwarding are dicussed, e.g. in terms of Simplified Multicast Forwarding (SMF, [9]) or for infrastructure mesh networks. 4. Security Considerations This document summarizes discussion of multicast extensions to mobility. New methods or procedures have not been proposed. Relevant issues for security and security have already been mentioned exhaustively in [6]. 5. Summary and Future Steps This document shall provide a future extension of the scope of Multicast Mobility within the framework of IETF WG with focus on deployable and operational solutions. 6. IANA Considerations There are no IANA considerations introduced by this draft. 7. References Normative References [1] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. [2] Vida, R. and L. Costa, "Multicast Listener Discovery Version 2 (MLDv2) for IPv6", RFC 3810, June 2004. [3] Tsirtsis, G., Park, V., and Soliman, H., "Dual-Stack Mobile IPv4", RFC 5454, March 2009 [4] Devarapalli, V., Wakikawa, R., Petrescu, A., and P. Thubert, "Network Mobility (NEMO) Basic Support Protocol", RFC 3963, January 2005. [5] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in IPv6", RFC 3775, June 2004. von Hugo, et al. Expires - April 2010 [Page 7] multimob-future-work October 2009 Informative References [6] Schmidt, T.C., Waehlisch, M., and Fairhurst, G., "Multicast Mobility in MIPv6: Problem Statement and Brief Survey", draft-irtf-mobopts-mmcastv6-ps-08.txt, (work in progress), August 2009. [7] Jeon, S., Kim, Y., and Lee, J., "Mobile Multicasting Support in Proxy Mobile IPv6", draft-sijeon-multimob-mms-pmip6-00.txt, (work in progress), July 2009. [8] Schmidt, T.C., Waehlisch, M., Sarikaya, B., and Krishnan, S., "A Minimal Deployment Option for Multicast Listeners in PMIPv6 Domains", draft-schmidt-multimob-pmipv6-mcast-deployment-01.txt, (work in progress), June 2009. [9] Macker, J., et al., "Simplified Multicast Forwarding", draft-ietf-manet-smf-09, (work in progress), July 2009 [10] Krishnan, S., Sarikaya, B., and Schmidt, T.C., "Proxy Mobile IPv6 Basic Multicast Support Solution", draft-krishnan-multimob- pmip6basicmcast-solution-00, (work in progress), July 2009. Acknowledgments The authors would thank all active mebers of MultiMob WG for providing continuous support, especially for Thomas Schmidt, Matthias Waehlisch, and Gorry Fairhurst for their fundamental document, Jouni Korhonen and Behcet Sarikaya for helpful comments and review. Authors' Addresses Dirk v. Hugo Deutsche Telekom AG Laboratories Deutsche-Telekom-Allee 7 D-64295 Darmstadt, Germany Email: Dirk.von-Hugo@Telekom.de von Hugo, et al. Expires - April 2010 [Page 8] multimob-future-work October 2009