> Step one would probably be a PIM-DM, later on it can be expanded to support > PIM-SM.
Hmm - is there still a userbase for DM that would warrant supporting it first from a practical standpoint, or is it simply that it is much easier to code and lays the groundwork for SM without diverting resources from SM too much? My only frame of reference is the advanced higher-ed community, where only the "opt-in" explicit-join paradigm of SM is in use. Flood-and-prune ("opt-out") is explicitly NOT recommended for use in a production environment at this point. RFC2362 has been obsoleted by draft-ietf-pim-sm-v2-new-11.txt, FWIW. Since it's an expired draft and could well evolve further, I don't know if you would want to use it - but its the current thinking by the WG: PIM-SM version 2 was originally specified in RFC 2117, and revised in RFC 2362. This document is intended to obsolete RFC 2362, and to correct a number of deficiencies that have been identified with the way PIM-SM was previously specified. As far as possible, this document specifies the same protocol as RFC 2362, and only diverges from the behavior intended by RFC 2362 when the previously specified behavior was clearly incorrect. Routers implemented according to the specification in this document will be able to successfully interoperate with routers implemented according to RFC 2362. -dd