MULTIMOB Group D. von Hugo Internet-Draft Telekom Innovation Laboratories Intended status: Experimental H. Asaeda Expires: August 16, 2013 NICT February 12, 2013 Context Transfer Protocol Extension for Multicast draft-vonhugo-multimob-cxtp-extension-03 Abstract This document describes an extension of the Context Transfer Protocol (CXTP) to support seamless IP multicast services with Proxy Mobile IPv6 (PMIPv6). Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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. 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Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. von Hugo & Asaeda Expires August 16, 2013 [Page 1] Internet-Draft CXTP Extension for Multicast February 2013 This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions and Terminology . . . . . . . . . . . . . . . . . 4 3. Handover Process . . . . . . . . . . . . . . . . . . . . . . . 5 3.1. Multicast Context Transfer Data Format . . . . . . . . . . 5 3.2. Multicast Context Transfer with MLD Proxy . . . . . . . . 6 3.3. Multicast Context Transfer with PIM-SM . . . . . . . . . . 9 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 5. Security Considerations . . . . . . . . . . . . . . . . . . . 12 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 7.1. Normative References . . . . . . . . . . . . . . . . . . . 14 7.2. Informative References . . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16 von Hugo & Asaeda Expires August 16, 2013 [Page 2] Internet-Draft CXTP Extension for Multicast February 2013 1. Introduction This document describes an extension of the Context Transfer Protocol (CXTP) [9] to provide seamless handover for multicast communications operated with Proxy Mobile IPv6 (PMIPv6) [2]. When a mobile node receiving multicast data detaches from the current MAG and attaches to a new MAG, the node should be able to continuously receive the multicast data through the new MAG just after the node completed handover without any MLD signaling on the new wireless link. This procedure is multicast context transfer that provides multicast session continuity and avoids extra packet loss and session disruption. Multicast context transfer is proposed as the required function to support seamless handover, while for its effective procedure, interaction with multicast communication protocols should be taken into account. The Context Transfer Protocol (CXTP) specification [9] describes the mechanism that allows better support for minimizing service disruption during handover. In this document, CXTP is extended for the multicast context transfer protocol in PMIPv6. "Multicast- Context Transfer Data (M-CTD)" is defined for transferring multicast membership state from a previously attached MAG (p-MAG) to a newly attached MAG (n-MAG) for PMIPv6. The context transfer is either started from the n-MAG on its own after attachment of the mobile node or initiated by the p-MAG after being informed by the access network of the planned handover. For data exchange between p-MAG and n-MAG a dedicated tunnel is assumed to be in place. Whether this p-MAG - n-MAG tunnel has already been set up in advance or will be initiated during handover by either p-MAG or n-MAG will impact the overall session delay. Details of this set-up procedure are out of scope of this document. An approach to apply CXTP to multicast for client-based mobile IPv6 had been proposed in [13]. Similarily to other approaches for increasing the efficiency of mobile multicast handover such as [14] describing the mechanism of Subscription Information Acquisition through the LMA (SIAL) for PMIPv6 the procedure described within this draft assumes that both the current and the new MAG are assigned to the same LMA. An extension for inter-LMA handover is topic for further study. von Hugo & Asaeda Expires August 16, 2013 [Page 3] Internet-Draft CXTP Extension for Multicast February 2013 2. Conventions and Terminology 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]. The following terms used in this document are to be interpreted as defined in the Proxy Mobile IPv6 specification [2]; Mobile Access Gateway (MAG), Local Mobility Anchor (LMA), Mobile Node (MN), Proxy Mobile IPv6 Domain (PMIPv6-Domain), LMA Address (LMAA), Proxy Care-of Address (Proxy-CoA), Mobile Node's Home Network Prefix (MN-HNP), Mobile Node Identifier (MN-Identifier), Proxy Binding Update (PBU), and Proxy Binding Acknowledgement (PBA). von Hugo & Asaeda Expires August 16, 2013 [Page 4] Internet-Draft CXTP Extension for Multicast February 2013 3. Handover Process MAG is responsible for detecting the mobile node's movements to and from the access link and for initiating binding registrations to the mobile node's LMA. MAG tracks the mobile node's movements to and from the access link and performs signaling of the status to the mobile node's LMA. In PMIPv6, it SHOULD NOT be required for mobile nodes to initiate re-subscription to multicast channels, and MAG SHOULD keep multicast membership state for mobile nodes even if they attach a different MAG in PMIPv6-Domain. For multicast context transfer, an IGMP/MLD-based explicit membership tracking function [11] MUST be enabled on MAG (whether the MAG behaves as a router or proxy). The explicit tracking function enables a router to keep track of downstream multicast membership state created by downstream hosts attached on the router's link. When a mobile node attaches to a new network, thanks to the explicit tracking function, the p-MAG extracts the mobile node's multicast membership state from complete multicast membership state the p-MAG has maintained and transmits it to the n-MAG. 3.1. Multicast Context Transfer Data Format Multicast Context Transfer Data (M-CTD) is a message used with CXTP to transfer multicast membership state from p-MAG to n-MAG. The following information is included in M-CTD to recognize mobile node's membership state. 1. Receiver address - indicates the address of the MN sending the Current-State Report. 2. Filter mode - indicates either INCLUDE or EXCLUDE as defined in [4]. 3. Source addresses and multicast addresses - indicates the address pairs the MN has joined. The M-CTD message MUST contain the 'A' bit set as defined for the CTD message format in [9] for to initiate the transmission of a reply message by the new MAG. The following information included in a reply to M-CTD (similar to the CTDR message defined in [9]) is used to request the old MAG to store still incoming multicast data, to forward them to the new MAG, and finally to terminate the multicast group subscription on behalf of the Mobile Node, i.e. to leave the multicast group when the handover from n-MAG to p-MAG has been successfully completed. von Hugo & Asaeda Expires August 16, 2013 [Page 5] Internet-Draft CXTP Extension for Multicast February 2013 1. Receiver address - indicates the address of the MN sending the Current-State Report. 2. Flag indicating the p-MAG to start (B) buffering the received multicast data (in case the new connection is not yet fully set up), to forward (F) the buffered data after successful handover, or to leave (L) the multicast groups unless there are still other active subscriptions for the corresponding groups on the p-MAG. 3. Source addresses and multicast addresses - indicates the address pairs the MN has joined. The M-CTDR message MUST contain the 'S' bit set as defined for the CTD message format in [9] for to indicate the successful reception of context data at the new MAG. The explicit tracking function [11] does not maintain information of an (S,G) join request with EXCLUDE filter mode. Therefore, when the "Filter mode" for a multicast session is EXCLUDE, "Source address" for the session MUST be set "Null". 3.2. Multicast Context Transfer with MLD Proxy This section describes the case that MAG operates as an MLD proxy, as defined in [6] and specified in the base MultiMob solution [10]. The MLD listener handover with CXTP and MLD proxy shown in Figure 1 is defined as follows. 1. After attaching a new MAG, a mobile node sends a Router Solicitation (RS) as specified in [7]. As the MN shall remain unaware of any change in connectivity the n-MAG has to identify the p-MAG address during proxy binding registration process with the mobile node's LMA. n-MAG then sends a request for context transfer (CT-Req) to the p-MAG as defined in [9]. Since the MN cannot initiate the related Context Transfer Activate Request (CTAR) message that may be sent by the LMA. In case the mobile node has the capability and the chance to signal to the p-MAG the link status and the potential new MAG address (e.g. as is specified in terms of Event Services by [8]) the p-MAG will send a CTAR message to n-MAG on behalf of the mobile node. Alternatively the p-MAG or the n-MAG may have information on potential MAGs in their vicinity to which such a CTAR or CT-Req message may be multicasted. von Hugo & Asaeda Expires August 16, 2013 [Page 6] Internet-Draft CXTP Extension for Multicast February 2013 2. p-MAG provides together with the other feature data the multicast states corresponding to the moving MN-Identifier to n-MAG. p-MAG utilizes a context transfer protocol to deliver MN's Policy Profile to n-MAG, and sends Multicast Context Transfer Data (M-CTD) (defined in Section 3.1) to n-MAG. 3. If there are multicast channels the MN has subscribed but the n-MAG has not yet subscribed, n-MAG subscribes via sending (potentially aggregated) MLD [4][5] Membership Report messages (i.e. Join) to the corresponding LMA. 4. n-MAG requests from p-MAG to store still incoming multicast data for transfer to MN after successful handover completion. For this purpose a newly defined B-flag in the Multicast Context Transfer Response message is sent from n-MAG to p-MAG, denoted as M-CTDR(B). 5. After successful completion of MN attachment to n-MAG the forwarding of the stored Multicast data from p-MAG to n-MAG is initiated via sending a Multicast Context Transfer Response message with a newly defined F-flag from n-MAG to p-MAG, denoted as M-CTDR(F). 6. LMA forwards requested multicast data to the n-MAG which subsequently delivers them to MN. 7. n-MAG may request from p-MAG to leave those multicast groups it had subscribed to on behalf of the MN where MN had been the last member. This is done via sending a Multicast Context Transfer Response message from n-MAG to p-MAG with a newly defined L-flag set, denoted as M-CTDR(L). von Hugo & Asaeda Expires August 16, 2013 [Page 7] Internet-Draft CXTP Extension for Multicast February 2013 MN p-MAG n-MAG LMA | | | | |-MLD Report->|==== MLD Report (aggregated Join) ====>| | | | | |<------------|<=========== Multicast data ===========| | | | | Detach | | | | | | | Attach | | | | | | | |------------- RS --------------->| | | | |------- PBU ------>| | | | | | | |<-------PBA--------| | | | | | |<----- CT-Req -----| | | | | | | |------ CXTP ------>| | | | M-CTD | | | | |=== MLD Report ===>| | |<------ CXTP ------| | | | M-CTDR(B) | | | | | | |<----------- RA -----------------| | | | |<= Multicast data =| | |<------ CXTP ------| | | | M-CTDR(F) | | | | | | | |= Multicast data =>| | | |<------ CXTP ------| | | | M-CTDR(L) | | | | | | |<-------- Multicast data --------| | | | | | | |========= MLD Report (leave) =========>| | | | | Figure 1: MLD listener handover with CXTP and MLD proxy After MN attaches to n-MAG, the forwarded multicast data from p-MAG will be delivered to the MN immediately. Afterwards the current multicast data are delivered as received from LMA and the MN's multicast membership state at the p-MAG is cancelled. von Hugo & Asaeda Expires August 16, 2013 [Page 8] Internet-Draft CXTP Extension for Multicast February 2013 3.3. Multicast Context Transfer with PIM-SM This section describes the case that MAG operates as a PIM-SM [3] router, as described in a proposed solution [12]. The MLD listener handover with CXTP and PIM-SM shown in Figure 2 is defined as follows. 1. The first and second procedures are the same ones as described in Section 3.2. 2. If there are multicast channels the MN has subscribed but the n-MAG has not yet subscribed, n-MAG joins the multicast tree via sending PIM Join messages to the upstream router (Figure 2 shows the example that the upstream router is the corresponding LMA). 3. The remaining steps for completion of the context transfer are the same ones as described in Section 3.2 with the only exception being that p-MAG sends a PIM Prune message to LMA instead of a MLD Report (leave) message if there are no attached mobile nodes listening the multicast channels. von Hugo & Asaeda Expires August 16, 2013 [Page 9] Internet-Draft CXTP Extension for Multicast February 2013 MN p-MAG n-MAG LMA | | | | |-MLD Report->|=============== PIM Join =============>| | | | | |<------------|<=========== Multicast data ===========| | | | | Detach | | | | | | | Attach | | | | | | | |------------- RS --------------->| | | | |------- PBU ------>| | | | | | | |<-------PBA--------| | | | | | |<----- CT-Req -----| | | | | | | |------ CXTP ------>| | | | M-CTD | | | | |===== PIM Join ===>| | |<------ CXTP ------| | | | M-CTDR(B) | | | | | | |<----------- RA -----------------| | | | |<= Multicast data =| | |<------ CXTP ------| | | | M-CTDR(F) | | | | | | | |= Multicast data =>| | | |<------ CXTP ------| | | | M-CTDR(L) | | | | | | |<-------- Multicast data --------| | | | | | | |============== PIM Prune =============>| | | | | | | | | Figure 2: MLD listener handover with CXTP and PIM-SM von Hugo & Asaeda Expires August 16, 2013 [Page 10] Internet-Draft CXTP Extension for Multicast February 2013 4. IANA Considerations This document proposes to extent messages defined by the experimental Context Transfer Protocol [9], i.e. the Context Transfer Data (CTD) Message and the Context Transfer Data Reply (CTDR) Message to enable transfer of multicast related data, i.e. M-CTD and M-CTDR. The data consist of subscription states and flags indicating specific actions to the MAG. Such extensions in terms of options, flags, and new parameters as described in sect. 3, 3.1., and 3.2. of this draft shall be allocated by IANA according to the instructions given in [15]. von Hugo & Asaeda Expires August 16, 2013 [Page 11] Internet-Draft CXTP Extension for Multicast February 2013 5. Security Considerations TBD. von Hugo & Asaeda Expires August 16, 2013 [Page 12] Internet-Draft CXTP Extension for Multicast February 2013 6. Acknowledgements Many of the specifications described in this document are discussed and provided by the MultiMob mailing-list. Detailed comments by Luis Miguel Contreras Murillo are gratefully acknowledged. von Hugo & Asaeda Expires August 16, 2013 [Page 13] Internet-Draft CXTP Extension for Multicast February 2013 7. References 7.1. Normative References [1] Bradner, S., "Key words for use in RFCs to indicate requirement levels", RFC 2119, March 1997. [2] Gundavelli, S, Ed., Leung, K., Devarapalli, V., Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. [3] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas, "Protocol Independent Multicast - Sparse Mode (PIM-SM): Protocol Specification (Revised)", RFC 4601, August 2006. [4] Vida, R. and L. Costa, "Multicast Listener Discovery Version 2 (MLDv2) for IPv6", RFC 3810, June 2004. [5] Liu, H., Cao, W., and H. Asaeda, "Lightweight IGMPv3 and MLDv2 Protocols", RFC 5790, August 2010. [6] Fenner, B., He, H., Haberman, B., and H. Sandick, "Internet Group Management Protocol (IGMP) / Multicast Listener Discovery (MLD)-Based Multicast Forwarding ("IGMP/MLD Proxying")", RFC 4605, August 2006. [7] Singh, H., Beebee, W., and E. Nordmark, "IPv6 Subnet Model: The Relationship between Links and Subnet Prefixes", RFC 5942, July 2010. [8] "IEEE Standard for Local and Metropolitan Area Networks - Part 21: Media Independent Handover Services, IEEE LAN/MAN Std 802.21-2008", January 2009. 7.2. Informative References [9] Loughney, Ed., J., Nakhjiri, M., Perkins, C., and R. Koodli, "Context Transfer Protocol (CXTP)", RFC 4067, July 2005. [10] Schmidt, T., Waehlisch, M., and S. Krishnan, "Base Deployment for Multicast Listener Support in Proxy Mobile IPv6 (PMIPv6) Domains", RFC 6224, April 2011. [11] Asaeda, H., "IGMP/MLD-Based Explicit Membership Tracking Function for Multicast Routers", draft-ietf-pim-explicit-tracking-04.txt (work in progress), January 2013. [12] Asaeda, H. and P. Seite, "Multicast Routing Optimization by von Hugo & Asaeda Expires August 16, 2013 [Page 14] Internet-Draft CXTP Extension for Multicast February 2013 PIM-SM with PMIPv6", draft-asaeda-multimob-pmip6-extension-11.txt (work in progress), October 2012. [13] Miloucheva, I. and K. Jonas, "Multicast Context Transfer in mobile IPv6", draft-miloucheva-mldv2-mipv6-00.txt (work in progress), June 2005. [14] Contreras, LM., Bernardos, CJ., and I. Soto, "PMIPv6 multicast handover optimization by the Subscription Information Acquisition through the LMA (SIAL)", draft-ietf-multimob-handover-optimization-01.txt (work in progress), December 2012. [15] Kempf, J., "Instructions for Seamoby and Experimental Mobility Protocol IANA Allocations", RFC 4065, July 2005. von Hugo & Asaeda Expires August 16, 2013 [Page 15] Internet-Draft CXTP Extension for Multicast February 2013 Authors' Addresses Dirk von Hugo Telekom Innovation Laboratories Deutsche-Telekom-Allee 7 D-64295 Darmstadt Germany Email: Dirk.von-Hugo@telekom.de Hitoshi Asaeda National Institute of Information and Communications Technology Network Architecture Laboratory 4-2-1 Nukui-Kitamachi Koganei, Tokyo 184-8795 Japan Email: asaeda@nict.go.jp von Hugo & Asaeda Expires August 16, 2013 [Page 16]