MULTIMOB Group S. Figueiredo Internet Draft R. L. Aguiar Intended status: Standards Track Universidade de Aveiro Expires: August 4, 2012 S. Jeon Instituto de Telecomunicacoes March 5, 2012 IP Multicast Use Case Analysis for PMIPv6-based Distributed Mobility Management draft-sfigueiredo-multimob-use-case-dmm-00 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." 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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. Abstract As mobile networks are moving towards distributed mobility management, the application of IP multicast is needed to provide efficient content delivery on the network. This document describes use cases when IP multicast is applied on PMIPv6-based DMM, and analyzes problems focused on user plane issues. Table of Contents 1. Introduction ................................................ 3 2. Conventions and Terminology.................................. 3 3. Use Cases Description........................................ 4 3.1. Multicast listener support.............................. 4 3.1.1. MLD-P in MAR....................................... 4 3.1.1.1. Duplicated Traffic............................ 5 3.1.1.2. Non-optimal routing........................... 6 3.1.2. Multicast Router in MAR............................ 7 3.2. Multicast sender support................................ 7 3.2.1. MLD-P in MAR....................................... 7 3.2.1.1. Triangular routing............................ 8 3.2.2. Multicast Router in MAR........................... 10 4. IANA Considerations ........................................ 11 5. Security Considerations..................................... 11 6. References ................................................. 11 6.1. Normative References................................... 11 6.2. Informative References................................. 11 Figueiredo, et al. Expires November 30, 2012 [Page 2] Internet-Draft Use Cases for Multicast DMM March 2012 1. Introduction As a consequence of forthcoming multimedia avalanche, several optimization mechanisms are being considered towards efficient and resilient mobile networks. As verified in [DDMM-MI], current IP mobility management solutions have limitations in supporting efficient management and deployment. Thus, several proposals aiming at the distribution of the mobility management functions [DDMM-FP] were presented. While the problems resulting from the application of mobility solutions in multicast traffic are known, affecting its efficiency and leading to non-negligible service disruption, among others ([IPMM][RFC5757]). It is still not clear how the change from centralized to distributed mobility solutions may affect IP multicast support. This document briefly describes use cases of IP multicast in a PMIPv6-based DMM environment, and analyses consequent problems. Both listener and sender perspective are studied, with MLD Proxy and Multicast Router at the Mobility Access Router (MAR). 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 [RFC2119]. This document uses the terminology defined in [RFC5213], [RFC6275], and [RFC3810], and [RFC4601]. Specifically, the definition of PMIPv6 domain is reused from [RFC5213] and reproduced here for completeness. - Mobility Access Router (MAR): A router with the capability of acting both as a mobility anchor and as an access router, in a per flow basis. - Previous Mobility Access Router (P-MAR): The MAR where the MN was attached to previously to the network-layer mobility process, and that may be acting as an anchor for one or multiple flows. - New Mobile Access Gateway (N-MAR): The MAR to which the MN is currently attached, providing the access functionality and thus delivers all the flows destined to the MN. - Multicast Listener Discovery Proxy (MLD-P): An entity following [RFC4605]. Figueiredo, et al. Expires November 30, 2012 [Page 3] Internet-Draft Use Cases for Multicast DMM March 2012 3. Use Cases Description This draft focuses on describing problems that occur when deploying IP multicast on a general PMIPv6-derived DMM architecture, as there is not yet a fully specified unicast DMM protocol. So, the unicast DMM concept used in this document is assumed as follows: MAG and an LMA functionalities defined in [RFC5213] are equipped within a same physical entity, called MAR, and a MAR provides tunnel-based forwarding to provide a home network prefix (HNP)-based flow necessary IP session continuity whenever the MN having assigned HNP moves to another MAR. 3.1. Multicast listener support 3.1.1. MLD-P in MAR Once a MN initially attaches to the P-MAR as shown in Figure 1), it receives a home prefix address, which will be associated with communications started at that MAR. The P-MAR transmits an MLD Query message towards the MN and receives the MLD Report messages from the MN. On receiving MLD Proxy message from the MN, the P-MAR tries to join multicast network. When joining procedure ends, multicast data is transmitted using IP multicasting scheme. +----------------+ | Multicast | | Infrastructure | +----------------+ * * (S,G) * +----------+ +----------+ | P-MAR |---------------| N-MAR | | |***************| | | (MLD-P) |---------------| (MLD-P) | +----------+ +----------+ * * * * +------+ +------+ | MN | -----> | MN | +------+ +------+ Figure 1 Multicasting architecture using distributed mobility management Figueiredo, et al. Expires November 30, 2012 [Page 4] Internet-Draft Use Cases for Multicast DMM March 2012 When the MN moves to the N-MAR, the N-MAR is required to establish a tunnel for IP session continuity of the packets towards the HNP assigned from the P-MAR as soon as the N-MAR detects that the MN came from the P-MAR. Following the operation of the MLD-P [RFC4605] on the N-MAR, the MLD-P instance on the N-MAR configures the upstream interface towards the P-MAR associated with the MN when Base Solution, defined in [RFC6224], is applied to the DMM. This is simple and applicable as a network-based multicast DMM approach. However, a couple of relevant issues happen. 3.1.1.1. Duplicated Traffic One problem is duplicated traffic, which is similar to the tunnel convergence problem occurring in [RFC6224], as shown in Figure 2. MN1 and MN3, which moved from MAR1 and MAR3, respectively, are currently located at the MAR2. Through respective established tunnels for MN1 and MN3, they receive multicast packets of the same channel through different MARs. This causes duplicated traffic, converging to the MAR2. The magnitude of replicated traffic will be much bigger than that of PMIPv6 because it is expected that the number of MARs at access level that will be deployed is much larger than that of LMAs at core level within a PMIPv6 domain. As referred, when a MN first subscribes multicast content, its current MAR's MLD-P will forward its subscription to the multicast infrastructure. As such, an extra duplication factor may occur, if the subscription being done is already being received from one or multiple tunnels due to other listeners (refer to MN2 from Figure 2 for an example). Figueiredo, et al. Expires November 30, 2012 [Page 5] Internet-Draft Use Cases for Multicast DMM March 2012 +----------------+ | Multicast Tree | * +----------------+ * * * * * * * * * * (S,G) * (S,G) * * (S,G) * * * +----------+ (-->) +----------+ (<--) +----------+ | MAR1 |---------| MAR2 |---------| MAR3 | | |*********| |*********| | | (MLD-P) |---------| (MLD-P) |---------| (MLD-P) | +----------+ Tun.1 +----------+ Tun.2 +----------+ * * * * * * * * * +---+ move +---+ +---+ +---+ move +---+ |MN1| ---> |MN1| |MN2| |MN3| <--- |MN3| +---+ +---+ +---+ +---+ +---+ (<--/-->) : direction of the multicast packet flow Figure 2 Data replication 3.1.1.2. Non-optimal routing Another issue is non-optimal routing (Figure 3). If we consider a significantly large domain, there is the possibility that the multicast packets need to traverse a long distance, depending on the setup of the upstream interface of MLD-P instance, even through the current MAR is connected to the multicast infrastructure. If an operator wants to deploy the upstream interface of all the MARs towards multicast source or multicast routing network, this issue doesn't happen and such an approach is extremely simple and mobility- agnostic way but there may occur media synchronization issue. Figueiredo, et al. Expires November 30, 2012 [Page 6] Internet-Draft Use Cases for Multicast DMM March 2012 +----------------+ | Multicast | | Infrastructure | +----------------+ * * (S,G) * +----------+ +----------+ | P-MAR |------ ------| N-MAR | | |****** ... ******| | |(MLD-P) |------ ------| (MLD-P) | +----------+ +----------+ * * * * +------+ +------+ | MN | -----> | MN | +------+ +------+ Figure 3 Non-optimal routing problem 3.1.2. Multicast Router in MAR TBD 3.2. Multicast sender support To provide sender multicasting support, a MAR may be required to act as MLD-P or multicast router. Depending on the equipped fuctions, we describe issues for multicast sender support. 3.2.1. MLD-P in MAR In order for the multicast content to reach the multicast tree, the MLD-P SHOULD configure its upstream interface towards a MR [PM-HOME]. In the case of MR or MAR, it MAY act as the Rendezvous Point (RP) but cause frequent multicast tree reconstruction and associated service disruptions whenever the MN moves. Figueiredo, et al. Expires November 30, 2012 [Page 7] Internet-Draft Use Cases for Multicast DMM March 2012 +------+ +----------------+ | RP |---------| Multicast | +------+ | Infrastructure | * +----------------+ * (S,G) | * | +----------+ +----------+ | P-MAR |----------| N-MAR | | |**********| | | (MLD-P) |----------| (MLD-P) | +----------+ +----------+ * * * * +------+ +------+ | S | ----> | S | +------+ +------+ Figure 4 Multicast sender mobility 3.2.1.1. Triangular routing When a listener attaches to a MAR where a source is transmitting, if the multicast traffic may be anchored through not current MAR (not MAR2 but MAR1 in Figure 5, and then multicast data would be reached through the mobility tunnel between MAR2 to MAR1. An listener (L1), subscribed to the source's channel, receives the multicast content from multicast infrastructure, therefore a non-optimal route is made. Figueiredo, et al. Expires November 30, 2012 [Page 8] Internet-Draft Use Cases for Multicast DMM March 2012 +------+ +----------------+ | RP |*********| Multicast | +------+ | Infrastructure | * +----------------+ * (S,G) * * * +----------+ +----------+ | MAR1 |-------| MAR2 | | |*******| | | (MLD-P) |-------| (MLD-P) | +----------+ +----------+ * * * * * * +------+ move +------+ +-----+ | S | ---> | S | | L1 | +------+ +------+ +-----+ Figure 5 Triagular routing after source mobility The same problem also occurs in the opposite process, i.e. if a multicast source starts transmitting multicast content at a MAR, and a listener moves to the same MAR while receiving the source's content (Figure 6). +------+ +----------------+ | RP |*********| Multicast | +------+ | Infrastructure | * +----------------+ * (S,G) * * * +----------+ +----------+ | MAR1 |-------| MAR2 | | |*******| | | (MLD-P) |-------| (MLD-P) | +----------+ +----------+ * * * * * * +------+ +----+ move +----+ | S | | L1 | <--- | L1 | +------+ +----+ +----+ Figure 6 Triangular routing after listener mobility Figueiredo, et al. Expires November 30, 2012 [Page 9] Internet-Draft Use Cases for Multicast DMM March 2012 When the source and the listener are within same MAR (MAR2) as their anchor, if both the source/listener try to start the session and the receive it, respectively at MAR2, the traffic will be optimally sent to the listener. As the traffic reaches the MLD-P via the downstream interface to which the source is attached, it will be sent through the interface through which the listener sent the MLD Report. However, if the source and the listener move to different MARs, the traffic will traverse the following non-optimal path, even though they share a common MAR2: S -> Source's MAR1 -> MAR2 -> Multicast Tree -> MAR2 -> Listener's MAR3 This problem is depicted in Figure 7. +----------------+ | Multicast Tree | +----------------+ * * * * * * * * * * +----------+ (-->) +----------+ (-->) +----------+ | MAR1 |---------| MAR2 |---------| MAR3 | | |*********| |*********| | | (MLD-P) |---------| (MLD-P) |---------| (MLD-P) | +----------+ Tun.1 +----------+ Tun.2 +----------+ * * * * * * * * * * * * +---+ move +---+ +---+ move +---+ | S | <--- | S | | L | --> | L | +---+ +---+ +---+ +---+ (<--/-->) : direction of the multicast packet flow Figure 7 Non-optimal routing due to mobile sender 3.2.2. Multicast Router in MAR TBD Figueiredo, et al. Expires November 30, 2012 [Page 10] Internet-Draft Use Cases for Multicast DMM March 2012 4. IANA Considerations This document makes no request of IANA. 5. Security Considerations TBD 6. References 6.1. Normative References [RFC2119] S. Bradner, "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March 1997. [RFC6275] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in IPv6", RFC 6275, July 2011. [RFC3810] R. Vida, and L. Costa, "Multicast Listener Discovery Version 2 (MLDv2) for IPv6," IETF RFC 3810, June 2004. [RFC5213] S. Gundavelli, K. Leung, V. Devarapalli, K. Chowdhury, and B. Patil, "Proxy Mobile IPv6", IETF RFC 5213, August 2008. [RFC4605] B. Fenner, H. He, B. Haberman, and H. Sandick, "Internet Group Management Protocol (IGMP) / Multicast Listener Discovery (MLD) Based Multicast Forwarding ("IGMP/MLD Proxying")", IETF RFC 4605, August 2006. [RFC4601] B. Fenner, M. Handley, H. Holbrook, and I. Kouvelas, "Protocol Independent Multicast - Sparse Mode (PIM-SM): Protocol Specification (Revised)", RFC 4601, August 2006. 6.2. Informative References [RFC5757] T. Schmidt, M. Waehlisch, and G. Fairhurst, "Multicast Mobility in Mobile IP Version 6 (MIPv6): Problem Statement and Brief Survey," RFC 5757, February 2010. Figueiredo, et al. Expires November 30, 2012 [Page 11] Internet-Draft Use Cases for Multicast DMM March 2012 [RFC6224] T. Schmidt, M. Waehlisch, S. Krishnan, "Base Deployment for Multicast Listener Support in PMIPv6 Domain," RFC 6224, April 2011. [DDMM-FP] P. Bertin, S. Bonjour, and J.-M., Bonnin, "A Distributed Dynamic Mobility Management Scheme Designed for Flat IP Architectures," Proc. of NTMS 2008. , November 2008. [DDMM-MI] H. A. Chan, H. Yokota, J. Xie, P. Seite, D. Liu, "Distributed and Dynamic Mobility Management in Mobile Internet: Current Approaches and Issues", Journal of Communications, vol. 6, no. 1, pp. 4-15, February 2011. [IPMM] I. Romdhani, M. Kellil, and H. Lach, "IP Mobile Multicast : Challenges and Solutions," IEEE Communications Surveys & Tutorials, vol. 6, no. 1, pp. 18-41, 2004. [PM-HOME] S. Jeon, N. Kang, and Y. Kim, "Mobility Management based on Proxy Mobile IPv6 for Multicasting Services in Home Networks," IEEE Transactions on Consumer Electronics (TCE), vol. 55, no. 3, pp. 1227-1232, August 2009. Figueiredo, et al. Expires November 30, 2012 [Page 12] Internet-Draft Use Cases for Multicast DMM March 2012 Authors' Addresses Sergio Figueiredo Instituto de Telecomunicacoes Campus Universitario de Santiago 3810-193 Aveiro, Portugal E-mail: sfigueiredo@av.it.pt Seil Jeon Instituto de Telecomunicacoes Campus Universitario de Santiago 3810-193 Aveiro, Portugal E-mail: seiljeon@av.it.pt Rui L. Aguiar Instituto de Telecomunicacoes Campus Universitario de Santiago 3810-193 Aveiro, Portugal E-mail: ruilaa@ua.pt Figueiredo, et al. Expires November 30, 2012 [Page 13]