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]
