Subject: RE: [Int-area] Re: I-D ACTION:draft-fenner-iana-exp-2780-01.txt

From: "Dave Thaler" <[email-masked]>
Date: Thu, 12 Jan 2006 16:45:32 -0800

I believe this draft is useful.

Three issues:

1)
Brian Carpenter writes:
> > 2.4.2.  IPv4 Multicast
> >
> >    The globally routable group 224.0.1.20 is set aside for
> >    experimentation.  For certain experiments, the administratively
> >    scoped multicast groups defined in [RFC2365] may be
> >    useful.[[anchor10: Should there be a 'link-local' 224.0.0.x
> >    experiment group? --wcf]]
> 
> To me it doesn't really seem necessary. Any link-local resource is
> safe to use experimentally, subject to local administration.

Unfortunately, that's not really true.  Unlike in IPv6, there are no
link-local IPv4 multicast addresses which aren't in the range IANA uses
to assign to protocols to be hard-coded.  Per RFC 2365, IANA reserves 
a /24 in _every_ scope for it to use for this purpose.

http://www.iana.org/assignments/multicast-addresses
contains the list of the link-local assignments in the top section.

So I think there should indeed be a link-local 224.0.0.x experiment
group.  I think there is also justification for a scope-relative
experiment value.

2) Section 3.4.2 mentions an experimental IPv6 group address, but it 
would be good to add a statement (consistent with the 2nd sentence 
in 2.4.2) about the use of arbitrary scoped groups with the T=1 bit 
set.  In other words, whatever is said for IPv4 should be said for IPv6.

3) In the interest of saying what should not be done (like the statement
in section 1 about hard coding values), I believe section 3.4.1 (IPv6
Unicast Addresses) should contain a statement that it is inappropriate
to use RFC 3849 addresses in experiments.

-Dave

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---

From: Bill Fenner <[email-masked]>
Date: Mon, 23 Jan 2006 01:08:23 -0800

I just submitted a -02 rev.

Appendix A.  Changes from -01

   o  Added refs to 3849 and 3330 for things not to use in unicast
      addresses.

   o  Updated ULA ref to be 4193.

   o  Changed multiple "TBD1+TBD2" to TBD1 thru TBD8

   o  Added IPv6 multicast addresses with T bit.

   o  Added footnote to be included in all IANA registrations.

   o  Added link-local and scope-relative v4 multicast addresses

For those who wanted stronger references to 3692: can you suggest text
if what's there isn't enough?  It's referenced twice in the
introduction, and I added a footnote to be inserted into the IANA
registrations; if this doesn't satisfy the needs I need some help
figuring out what would.

Thanks,
  Bill