[pim] Registry for PIM message types

[Stig Venaas <stig at venaas.com>]

It turns out there is no registry for PIM message types. The only thing
we got is PIMv1 types as part of the IGMP registry.

There is an almost complete list of message types in the sparse mode and
dense mode RFCs, but none of them actually define a registry. This means
there is no IANA list of PIM message types, and there are no rules for
how to define new ones.

I've just submitted a very simple draft that defines such a registry,
see http://www.ietf.org/id/draft-venaas-pim-registry-00.txt

Below are the types it defines (have I missed any?).

It also says that IETF review is needed for new message types. That
means an RFC is needed and it must go through IETF last call (which
means that standards track RFCs are automatically qualified, but also
other RFCs if we do an IETF last call). Do you think that is too strict?

Message types in draft:

   Type   Name                          Reference
   ----  ----------------------------  ---------------------
     0    Hello                         [RFC3973] [RFC4601]
     1    Register                      [RFC4601]
     2    Register Stop                 [RFC4601]
     3    Join/Prune                    [RFC3973] [RFC4601]
     4    Bootstrap                     [RFC4601]
     5    Assert                        [RFC3973] [RFC4601]
     6    Graft                         [RFC3973]
     7    Graft-Ack                     [RFC3973]
     8    Candidate RP Advertisement    [RFC4601]
     9    State Refresh                 [RFC3973]
    10    DF Election                   [RFC5015]

Stig