SAM J. Buford, Panasonic Internet Draft January 14, 2007 Expires: July 14, 2007 Hybrid Overlay Multicast Framework draft-irtf-sam-hybrid-overlay-framework-00.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of 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 July 14, 2007. Copyright Notice Copyright (C) The Internet Society (2007). All Rights Reserved. Abstract We describe an experimental framework for constructing SAM sessions using hybrid combinations of Application Layer Multicast, native multicast, and multicast tunnels. We leverage AMT [THA2006] relay and gateway elements for interoperation between native regions and Buford Expires July 14, 2007 [Page 1] Internet-Draft SAM Problem Statement January 14, 2007 ALM regions. The framework allows different overlay algorithms and different ALM control algorithms to be used. Conventions used in this document In examples, "C:" and "S:" indicate lines sent by the client and server respectively. 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. Definitions....................................................3 2.1. Overlay Network...........................................3 2.2. Overlay Multicast.........................................4 3. Overlay Assumptions............................................4 4. ALM Tree Operations............................................4 5. Hybrid Connectivity............................................5 6. Scenarios......................................................6 7. Open Issues and Further Work...................................6 8. Security Considerations........................................7 9. References.....................................................7 9.1. Normative References......................................7 9.2. Informative References....................................7 Author's Addresses................................................8 Intellectual Property Statement...................................8 Disclaimer of Validity............................................9 Copyright Statement...............................................9 Acknowledgment....................................................9 1. Introduction The concept of scalable adaptive multicast [BUF2007] includes both scaling properties and adaptability properties. Scalability is intended to cover: o large group size o large numbers of small groups o rate of group membership change o admission control for QoS Buford Expires July 14, 2007 [Page 2] Internet-Draft SAM Problem Statement January 14, 2007 o use with network layer QoS mechanisms o varying degrees of reliability o trees connect nodes over global internet Adaptability includes o use of different control mechanisms for different multicast trees depending on initial application parameters or application class o changing multicast tree structure depending on changes in application requirements, network conditions, and membership o use of different control mechanisms and tree structure in different regions of network depending on native multicast support, network characteristics, and node behavior In this document we describe an experimental framework for constructing SAM sessions using hybrid combinations of Application Layer Multicast, native multicast, and multicast tunnels. 2. Definitions 2.1. Overlay Network P P P P P ..+....+....+...+.....+... . +P P+ . . +P ..+....+....+...+.....+... P P P P P Overlay network – An application layer virtual or logical network in which end points are addressable and that provides connectivity, routing, and messaging between end points. Overlay networks are frequently used as a substrate for deploying new network services, or for providing a routing topology not available from the underlying physical network. Many peer-to-peer systems are overlay networks that run on top of the Internet. In the above figure, P=Peers, and peers are connected in a logical address space. Buford Expires July 14, 2007 [Page 3] Internet-Draft SAM Problem Statement January 14, 2007 2.2. Overlay Multicast Overlay Multicast (OM): Hosts participating in a multicast session form an overlay network and only utilize unicast among pairs of hosts for data dissemination. The hosts in overlay multicast exclusively handle group management, routing, and tree construction, without any support from Internet routers. This is also commonly known as Application Layer Multicast (ALM) or End System Multicast (ESM). We call systems which use proxies connected in an overlay multicast backbone “proxied overlay multicast” or POM. 3. Overlay Assumptions Peers connect in a large-scale overlay, which may be used for a variety of peer-to-peer applications in addition to multicast sessions. We assume a single structured overlay routing algorithm is used. Any of a variety of multi-hop, one-hop, or variable-hop overlay algorithms could be used. Castro et al. [CAS2003] compared multi-hop overlays and found that tree-based construction in a single overlay out-performed using separate overlays for each multicast session. We use a single overlay rather than separate overlays per multicast sessions. We defer federated and hierarchical multi-overlay designs to later analysis. Peers may be distributed throughout the network, in regions where native multicast (NM) is available as well as regions where it is not available. Peers are able to determine, through configuration or discovery: o Can they connect to a NM router o Is an AMT gateway accessible o Can the peer support the AMT-GW functionality locally 4. ALM Tree Operations Peers use the overlay to support ALM operations such as: o Create tree o Join Buford Expires July 14, 2007 [Page 4] Internet-Draft SAM Problem Statement January 14, 2007 o Leave o Re-Form tree There are a variety of algorithms for peers to form multicast trees in the overlay. We permit multiple such algorithms to be supported in the overlay, since different algorithms may be more suitable for certain application requirements, and since we wish to support experimentation. Overlay messaging corresponding to the set of overlay multicast operations should carry algorithm identification information. In addition to these overlay level tree operations, some peers may implement additional operations to map tree operations to native multicast and/or AMT [THA2006] connections. 5. Hybrid Connectivity In the following figure we show the hybrid architecture in five regions of the network. o No native multicast: Peers (P) in this region connect to the overlay o Native multicast (NM) with a local AMT gateway (AMT GW). There are one or more peers (P) connected to the overlay in this region. o Native multicast with a local AMT relay (AMT RLY). There are one or more peers (P) connected to the overlay in this region. o Native multicast with one or more peers which emulate the AMT relay behavior (P-AMT-R) which also connect to the overlay. There may be other peers (P) which also connect to the overlay. o Native multicast with no peers that connect to the overlay, but for which there is at least one peer in the unicast-only part of the network which can behave as an AMT-GW (P-AMT-GW) to connect to multicast sources through an AMT-R for that region. It may be feasible to also allow non-peer hosts in such a region to participate as receivers of overlay multicast; for this version, we prefer to require all hosts to join the overlay as peers. Buford Expires July 14, 2007 [Page 5] Internet-Draft SAM Problem Statement January 14, 2007 +---------------+ +---------------+ | Native MCast | P P P P P | Native MCast | | ..........+...+....+....+...+.....+....+....... | | . +---++ ++---+ +P | | P+ |AMT | |AMT | . | | . |GW | |RLY | +P | | . +---++ ++---+ . | +-----+---------+ +------+--------+ . . P+....+P ............+P . . +--------+------+ . +---------------+ | Native . MCast| . |Native MCast | | . | P+ ++---+ | | P-AMT-R+ | . |AMT | | | . | P-AMT-GW+===|RLY | | | P-AMT-R+ | . ++---+ | | ...+...+...+....+........+.....+ | | | P | P P P P | | +---------------+ +---------------+ 6. Scenarios The next version of this document will elaborate: o Native region peer joins existing ALM tree o ALM peer joins existing Native Mcast, including: NM has AMT Relay ad NM does not have AMT Relay 7. Open Issues and Further Work o AMT [THA2006] has some restrictions on cases where sources and receivers can be located in the gateway-relay connections. Further analysis is needed to insure that OM data path is consistent with these constraints Buford Expires July 14, 2007 [Page 6] Internet-Draft SAM Problem Statement January 14, 2007 o For NM regions with no AMT support, specifics of how peers self- select as P-AMT-GW and P-AMT-RLY, and what additional behavior if any is needed beyond that specified in [THA2006]. o We expect that the evolution of this document will lead to protocol specification related to the interopation points of the hybrid interfaces of the network. 8. Security Considerations Overlays are vulnerable to DOS and collusion attacks. We are not solving overlay security issues. For this version we assume centralized peer authentication model similar to what is proposed for P2P-SIP. 9. References 9.1. Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 199 [RFC0792] Postel, J., "Internet Control Message Protocol", STD 5,RFC 792, September 1981. [RFC3376] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A. Thyagarajan, "Internet Group Management Protocol, Version 3", RFC 3376, October 2002. [RFC3810] Vida, R. and L. Costa, "Multicast Listener Discovery Version 2 (MLDv2) for IPv6", RFC 3810, June 2004. [RFC4605] 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. [RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for IP", RFC 4607, August 2006. 9.2. Informative References [MUR2006] E. Muramoto, Y. Imai, N. Kawaguchi. Requirements for Scalable Adaptive Multicast Framework in Non-GIG Networks. November 2006. Internet Draft draft-muramoto-irtf-sam- generic-require-01.txt, work in progress. Buford Expires July 14, 2007 [Page 7] Internet-Draft SAM Problem Statement January 14, 2007 [BUF2007] J. Buford, S. Kadadi. SAM Problem Statement. Dec 2006. Internet Draft draft-irtf-sam-problem-statement-01.txt, work in progress. [THA2006] D. Thale, M. Talwar, A. Aggarwal, L. Vicisano, T. Pusateri. Automatic IP Multicast Without Explicit Tunnels (AMT). Internet Draft draft-ietf-mboned-auto-multicast-07, Work in progress. Nov 2006. [CAS2003] M. Castro, M. Jones, A. Kermarrec, A. Rowstron, M. Theimer, H. Wang and A. Wolman, “An Evaluation of Scalable Application-level Multicast Built Using Peer-to-peer overlays,” in Proceedings of IEEE INFOCOM 2003, April 2003. Author's Addresses John Buford Panasonic Princeton Laboratory rd 2 Research Way, 3 Floor Princeton, NJ 08540, USA Email: buford@samrg.org Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement Buford Expires July 14, 2007 [Page 8] Internet-Draft SAM Problem Statement January 14, 2007 this standard. Please address the information to the IETF at ietf-ipr@ietf.org Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement Copyright (C) The Internet Society (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Buford Expires July 14, 2007 [Page 9]