Small Group Multicast BOF (sgm) Monday, July 31 at 1300-1500 ============================ CHAIR: Randy Bush DESCRIPTION: A number of people in the Internet community have been advocating that the IETF consider standardizing a method for handling multicast to small groups, where "small" is generally understood to be in the range of 3-10 or so participants. The rationale for this is twofold: 1) there are alleged to be a number of very important applications which have a small numbers of participants per group (e.g. classic audio and video conferencing, collaboration tools, etc.) with an extremely large number of such groups simultaneously active on the Internet. 2) Existing IP multicast methods, including newer specialized schemes like Source Specific Multicast (SSM) are generally thought to have scaling problems when there are a very large nubmer of groups, because of per-group state in all the intermediate routers. Because of the range of possible approaches to this problem and the potential widespread impact on portions of the IP protocol suite, router implementation, operational practices, etc. of the Internet, the BoF is being jointly hosted by the Routing and Internet areas, and will be chaired by Randy Bush of the OPS area. The BoF's goals are to: a) assess interest in forming a Working Group on Small Group Multicast b) produce a crisp problem statement which could be used as the basis for a Working Group Charter c) reach consensus on a set of constraints on the solution space (see below) d) examine existing work for possible solutions (see below) In order to have a technically sound and deployable solution, it is particularly important the scope of changes to the Internet architecturte, protocols, host & router implementations, and operational management be understood and hopefully minimized. Some of these possible constraints include: - Host API (e.g. sockets interface) changes allowed? - Host protocol implementation changes allowed? - IP packet header changes allowed? If so, effect on router forwarding speed? - New routing protocols needed? Modifications to existing multicast and/or unicast routing protocols? In order to stimulate discussion in advance of the BoF, we will use an existing mailing list set up by the folks who have been working on a set of approaches to SGM which are collectively known as explicit multicast, or "xcast". The mailing list is: xcast@public.alcatel.com and may be subscribed to by via xcast-reqeust@public.alcatel.com A detailed agenda will be provided in the next couple of weeks after initial discussion on the mailing list. An initial reading list for people interested in the discussion follows: 1) "Connectionless Multicast", draft-ooms-cl-multicast-01.txt 2) "Small Group Multicast", http://www.icair.org/main_projects_infrast_sgm.html 3) "Multiple Destination option on IPv6", draft-imai-mdo6-00.txt 4) "Distributed Core Multicast: a routing protocol for many small groups with application to mobile IP telephony", draft-blazevic-dcm-mobility-00.txt 5) "Datagram Routing for Internet Multicasting", L. Aguilar, Sigcomm84, March 1984 6) "IPv4 option for Sender Directed Multi-Destination Delivery", C. Graff, RFC1770 AGENDA: - Intro / Why are we here Randy Bush 5 minutes - Overview of SGM/Xcast Dirk Ooms 10 minutes - CLM Dirk Ooms 15 minutes - SGM Rick Boivie 15 minutes - MDO6 Yuji Imai 15 minutes - Xcast & SIP Bart Van Doorselaer 5 minutes - Security for Xcast Olivier Paridaens 10 minutes - Args for & against SGM/Xcast Rick Boivie 15 minutes - Discussion All 30 minutes