PIM Working Group Hong-Ke Zhang Internet Draft Shuai Gao Intended status: Standards Track Beijing Jiaotong University Expires: January 13, 2014 T C.Schmidt HAW Hamburg Bo-hao Feng Li-Li Wang Beijing Jiaotong University July 14, 2013 Multi-Upstream Interfaces IGMP/MLD Proxy draft-zhang-pim-muiimp-01.txt Abstract In this document, followed by the idea mentioned in [1] and subsequently updated in [2], an IGMP/MLD proxy with multiple upstream interfaces called MUIIMP is proposed and analyzed. The MUIIMP inherits the basic rule of the IGMP/MLD proxy but extends with multiple upstream interfaces. To avoid data redundancy, each upstream interface of an MUIIMP device MUST NOT send or subscribe to the same data simultaneously. Requirements Language 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 [RFC2119]. 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". Zhang et al. Expires January, 2014 [Page 1] Internet-Draft Multi-Upstream Interfaces IGMP/MLD Proxy July 2013 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 January, 2014. Copyright Notice Copyright (c) 2012 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 (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. 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. Table of Contents 1. Introduction....................................................3 2. Terminology.....................................................3 3. MUIIMP Operation................................................4 3.1. The selection of default upstream interface................5 3.2. Report of downstream subscriptions on upstream interfaces..5 3.3. Handover of the upstream interface.........................6 4. Use Case in PMIPv6 Environment..................................6 5. Security Considerations.........................................9 6. References......................................................9 Authors' Addresses................................................11 Acknowledgment....................................................11 Zhang et al. Expires January, 2014 [Page 2] Internet-Draft Multi-Upstream Interfaces IGMP/MLD Proxy July 2013 1. Introduction RFC 4605 [3] specifies an IGMP/MLD proxy mechanism for forwarding based solely upon IGMP/MLD membership information in scenarios where multicast routing is not available. According to RFC 4605, an IGMP/MLD proxy performs the router portion of the IGMP/MLD protocol [4-5] on its downstream interfaces, and the host portion of the IGMP/MLD protocol on its single upstream interface. The IGMP/MLD proxy mechanism can effectively extend the multicast scope and greatly simplify the implementation of edge devices. However, the IGMP/MLD proxy may exhibit inefficiency in some specific scenarios due to the limitation of single upstream interface. For example, in PMIPv6 multicast environment, multiple IGMP/MLD proxy instances need to be deployed at the MAG in RFC 6224 [6], which may result in tunnel convergence problem. In addition, there are also requirements to extend the IGMP/MLD proxy to support multiple upstream interfaces with the emergence of multi-homing. It is noted that the idea about multiple upstream interfaces for IGMP/MLD proxy was firstly proposed in the draft [1] to improve the performance of multicast source mobility. Subsequently, the Multimob working group draft [2] describes the multi-upstream interfaces IGMP/MLD proxy in detail. Considering the multiple upstream interfaces extension is not only required for mobile multicast sources scenarios, this document is presented here. In this document, an IGMP/MLD proxy with multiple upstream interfaces called MUIIMP is proposed and described. The MUIIMP inherits the basic rule of the IGMP/MLD proxy but extends with multiple upstream interfaces. To avoid data redundancy, each upstream interfaces of an MUIIMP device MUST NOT send or subscribe to the same data simultaneously. Additionally, the MUIIMP is designed to support local multicast listeners and senders. 2. Terminology Upstream Interface: A proxy device's interface in the direction of the root of the tree. Downstream Interface: Each of a proxy device's interfaces that is not in the direction of the root of the multicast tree. Default upstream interface: An upstream interface which is by default associated with each downstream node subscribing or sending specific channel (group address prefix) or special multicast state. Zhang et al. Expires January, 2014 [Page 3] Internet-Draft Multi-Upstream Interfaces IGMP/MLD Proxy July 2013 3. MUIIMP Operation The MUIIMP inherits the basic rule of the IGMP/MLD proxy but extends with multiple upstream interfaces. A MUIIMP device has one or more upstream as well as downstream interfaces, which may be any type interfaces, including physical or logical interfaces. The MUIIMP performs the router portion of the IGMP/MLD protocol on its downstream interfaces, and the host portion of IGMP/MLD on its upstream interfaces. The MUIIMP device MUST NOT perform the router portion of IGMP/MLD on its upstream interfaces. The MUIIMP device maintains a database for multicast listeners consisting of the merger of all subscriptions on any downstream interface. In order to avoid the redundant multicast traffic, the proxy device should initiate unique traffic subscriptions. Besides, a policy list that records the default upstream interface for the downstream nodes is held for the selection of upstream interface. According to the role of the downstream nodes, the operation of the MUIIMP device will be described as follows: 1) Multicast listener on the downstream interface Multicast listener reports are group-wise aggregated by the IGMP/MLD proxy. The aggregated report is issued to the upstream interface based on the subscriptions as well as the policy list. When receiving the IGMP/MLD subscriptions on the downstream interface, the MUIIMP decides whether to send the IGMP/MLD membership reports on the corresponding default upstream interface based on the membership database. The detailed membership subscriptions lookup and report decisions are discussed in Section 3.2. When receiving packets on its upstream interfaces, the MUIIMP forwards the traffic to all the downstream interfaces based upon the downstream interfaces' subscriptions. 2) Multicast source on the downstream interface When receiving packets on its downstream interface, the MUIIMP forwards the traffic to the corresponding default upstream interface as well as all the downstream interfaces other than the incoming interface based upon the downstream interfaces' subscriptions. The (first) multicast router(s) operating multicast routing protocol like PIM-SM [7] connected to the outside multicast domain should be configured to treat the multicast source inside the MUIIMP domain Zhang et al. Expires January, 2014 [Page 4] Internet-Draft Multi-Upstream Interfaces IGMP/MLD Proxy July 2013 being directly connected. Otherwise, it will discard the data due to the failure of the direct connection check. 3.1. The selection of default upstream interface Typically, the choice of the default upstream interface is based on the policy list which is maintained at the MUIIMP. The expression of the policy list is like below: (node prefix, multicast group address/multicast state, upstream interface) Here, node prefix represents the address prefix of the node on the downstream interface that may be a multicast listener or multicast source. The multicast group address indicates the channel that the multicast listener is subscribing or the multicast source is publishing, while the multicast state is only valid for listeners indicating the state about both multicast source and multicast group they are subscribing. In other word, in the MUIIMP, the multicast group address/multicast state and the node prefix will act as rules to select the default upstream interface. Alternate configurations (e.g., the MAG-LMA tunnel interface in the PMIPv6 environment) MAY be applied. 3.2. Report of downstream subscriptions on upstream interfaces To avoid the redundant multicast traffic, the proxy device MUST NOT send the same multicast subscription record on different upstream interfaces simultaneously. In detail, we recommend the following rules when receiving an IGMP/MLD subscription on the downstream interface. 1) If the received IGMP/MLD subscription is new and has not been subscribed by other downstream multicast listeners, the proxy device SHOULD initiate the IGMP/MLD subscription on the corresponding default upstream interface. 2) If there exists the same IGMP/MLD subscription which has already been subscribed by other downstream multicast listeners, the proxy device SHOULD not initiate extra IGMP/MLD subscription. 3) If there exists IGMP/MLD subscriptions which have already included the received IGMP/MLD subscription, the proxy device SHOULD not initiate extra IGMP/MLD subscription. Zhang et al. Expires January, 2014 [Page 5] Internet-Draft Multi-Upstream Interfaces IGMP/MLD Proxy July 2013 4) If there exists overlapping subsets between the received IGMP/MLD subscription and the current IGMP/MLD subscriptions, the proxy device SHOULD initiate the IGMP/MLD subscription on the corresponding default upstream interface excluding the overlapping subsets that have been subscribed before. All subscriptions sent on the same upstream interface SHOULD be merged according to the merging rule specified in RFC 4605. In addition, the local multicast source should be excluded in the final subscriptions to avoid replicated multicast traffic from outside. 3.3. Handover of the upstream interface If an upstream interface fails for some reason, such as the deletion of the tunnel interface in mobile environment, the handover of the upstream interface should be performed. Generally, all the subscriptions sent on the previous invalid upstream interface are transferred to the new valid upstream interfaces which are chosen among the default upstream interfaces of the corresponding downstream nodes. The choice may be made based on the predefined policy (e.g., the interface priority, the number of listeners, the lowest IP address). An alternative may be applied by the MUIIMP device itself according to the traffic monitored or some strategies configured by the operator. 4. Use Case in PMIPv6 Environment With the development of the Mobile IP-like protocols (such as, MIPv6, PMIPv6 and DMM), combining multicast with mobile protocols has been widely discussed. One way is to deploy traditional IGMP/MLD proxy at the gateway of mobile nodes [2,6], but there are some drawbacks like the detour routing and tunnel convergence problem. MUIIMP can be used to optimize the behavior of multicast mobility as well as to support the multi-homing/multi-interface for both the mobile nodes and the fixed nodes. Requirements for an IGMP/MLD proxy with multiple interfaces have been proposed in the draft [8], covering a variety of application scenarios. In this section, a use-case in PMIPv6 environment is presented to illustrate how the MUIIMP works. The basic deployment of MUIIMP in PIMPv6 networks is shown in Figure 1, in which there are three mobile nodes (MNs) belonging to different LMAs and attaching under the same MAG. Let's adopt the scheme in RFC 6224 [6] and assume that the default upstream interface for each MN in Figure 1 is the tunnel interface from the MAG to the corresponding LMA. In real environment, the MN may also express its preference on upstream interface selection by other means. Detailed multicast related information of each MN is depicted Zhang et al. Expires January, 2014 [Page 6] Internet-Draft Multi-Upstream Interfaces IGMP/MLD Proxy July 2013 in Table 1. We assume that MN1, MN2 and MN3 attach at the MAG in sequence. +-------------------------+ | Multicast Domain | ------------ +-------------------------+ | / | \ | +-------+ +-------+ +-------+ | | LMA-1 | | LMA-2 | | LMA-3 | | +-------+ +-------+ +-------+ | \\ || // | \\ || // | \\ ||IF-B // | \\ || // | \\ || // | IF-A \\ || // IF-C | +---------+ +-----+ MUIIMP | M A G | -----IF-D-------- | M R | +---------+ +-----+ / | \ MN-1 MN-2 MN-3 Figure 1: The basic deployment of MUIIMP in PIMPv6 networks Zhang et al. Expires January, 2014 [Page 7] Internet-Draft Multi-Upstream Interfaces IGMP/MLD Proxy July 2013 +----+-----+--------+---------------------+-----------------+ |Node| LMA | Type | Multicast Channel | Default U-IF | +----+-----+--------+---------------------+-----------------+ | | | | (m1,EXCLUDE,{}) | | | | | |---------------------| | |MN-1|LMA-1|Receiver| (m2,EXCLUDE,{}) | IF-A | | | | |---------------------| | | | | | (m3,INCLUDE,{a}) | | +----+-----+--------+---------------------+-----------------+ | | | | (m1,EXCLUDE,{}) | | | | | |---------------------| | |MN-2|LMA-2|Receiver| (m2,INCLUDE,{b}) | IF-B | | | | |---------------------| | | | | | (m3,EXCLUDE,{}) | | +----+-----+--------+---------------------+-----------------+ | | |Receiver| (m1,EXCLUDE,{}) | | |MN-3|LMA-3|--------|---------------------| IF-C | | | | Source | m2 | | +----+-----+--------+---------------------+-----------------+ Table 1: Detailed information of each MN The operation of the MUIIMP is described as follows: 1) MN1 firstly subscribes (m1,EXCLUDE,{}), (m2,EXCLUDE,{}) and (m3,INCLUDE,{a}), the MUIIMP initiates the corresponding IGMP/MLD subscription through the IF-A. Zhang et al. Expires January, 2014 [Page 8] Internet-Draft Multi-Upstream Interfaces IGMP/MLD Proxy July 2013 2) When MN2 (as well as MN3) subscribes (m1,EXCLUDE,{}), since there exists the same IGMP/MLD subscription through the IF-A, the MUIIMP will not initiate extra IGMP/MLD subscription. 3) When MN2 subscribes (m2,INCLUDE,{b}), since (m2,EXCLUDE,{}) has been subscribed, the MUIIMP does not initiate extra IGMP/MLD subscription. 4) When MN2 subscribes (m3,EXCLUDE,{}), since (m3,INCLUDE,{a}) has been subscribed through the IF-A, the MUIIMP will send IGMP/MLD subscription of (m3,EXCLUDE,{a}) through the IF-B. 5) When MN3 acts one of the sources for m2, traffic from MN3 are transmitted to the downstream interface towards MN1 as well as the IF-C. Besides, IGMP/MLD subscription of (m2,EXCLUDE,{}) sent by the MUIIMP through the IF-A is modified as (m2,EXCLUDE,{MN3}). 6) When MN1 hands over, the tunnel interface IF-A will be deleted and the MUIIMP needs to deal with this scenario because the subscriptions of MN2 and MN3 was sent through the IF-A previously. Here, IF-B and IF-C, as the default upstream interfaces of MN2 and MN3, are two candidate upstream interfaces for m1 subscription. Then, the predefined customized policy can be used to select a new U-IF from the candidate upstream interfaces. As for (m2,INCLUDE,{b}) and (m3,EXCLUDE,{}), they are only subscribed by the MN2, thus, the IF-B will be selected as the new U-IF for them. It is worth noting that the fixed node (FN) connecting to the MAG can be regarded as an MN that never handovers. The default upstream interface of FN can be an interface adjacent to multicast domain, like the IF-D in Figure 1. 5. Security Considerations To be done. 6. References [1] H. Zhang, Z. Yan, S. Gao, L. Wang, Q. Wu and H. Li, "Multicast Source Mobility Support in PMIPv6 Network", draft-zhang- multimob-msm-03, July 2011. [2] T C. Schmidt, S. Gao, H. Zhang and M. Waehlisch, "Mobile Multicast Sender Support in Proxy Mobile IPv6 (PMIPv6) Domains", draft-ietf-multimob-pmipv6-source-03, February 2013. Zhang et al. Expires January, 2014 [Page 9] Internet-Draft Multi-Upstream Interfaces IGMP/MLD Proxy July 2013 [3] B. Fenner, H. He, B. Haberman and H. Sandick, "Internet Group Management Protocol (IGMP) / Multicast Listener Discovery (MLD)-Based Multicast Forwarding ("IGMP/MLD Proxying")", RFC 4605, August 2006. [4] Cain, B., Deering, S., Kouvelas, I., Fenner, B. and A. Thyagarajan, "Internet Group Management Protocol, Version3", RFC 3376, October 2002. [5] Vida, R. and L. Costa, "Multicast Listener Discovery Version 2 (MLDv2) for IPv6", RFC 3810, June 2004. [6] T. Schmidt, M. Waehlisch and S. Krishnan, "Base Deployment forMulticast Listener Support in Proxy Mobile IPv6 (PMIPv6) Domains", RFC 6224, April 2011. [7] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas, "Protocol Independent Multicast - Sparse Mode (PIM-SM): Protocol Specification (Revised)", RFC 4601, August 2000. [8] LM. Contreras, CJ. Bernardos and JC. Zuniga, "Extension of the MLD proxy functionality to support multiple upstream interfaces", draft-contreras-multimob-multiple-upstreams-01, February 2013. Zhang et al. Expires January, 2014 [Page 10] Internet-Draft Multi-Upstream Interfaces IGMP/MLD Proxy July 2013 Authors' Addresses Hong-Ke Zhang, Shuai-Gao, Bo-Hao Feng, Li-Li Wang National Engineering Lab for NGI Interconnection Devices Beijing Jiaotong University, Beijing, China Phone: +861051684274 Email:hkzhang@bjtu.edu.cn shgao@bjtu.edu.cn 11111021@bjtu.edu.cn liliwang@bjtu.edu.cn Thomas C. Schmidt HAW Hamburg Berliner Tor 7 Hamburg 20099 Germany Email: schmidt@informatik.haw-hamburg.de URI: http://inet.cpt.haw-hamburg.de/members/schmidt Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Zhang et al. Expires January, 2014 [Page 11]