Hemant,

I have reviewed your draft and the discussion on the IPv6 list.

Its easy to believe that there are implementations out there
that get things wrong. I also agree with the general technical
direction about DAd and being specific about where ND on-link
assumptions and prefixes can come from. And we should
value implementation experience and document it where
it can potentially help future implementers.

However, we already had a discussion about whether the
2462bis document should change. The WG believes they
have gotten the current requirements right, and I can't really
blame them for that. Please note that once 2462bis is an RFC,
IETF's official recommendation is to do exactly what you
want to happen. Those implementations that pay attention
to such things will change (if they need to). It is unfortunate
that earlier RFCs and some implementations operated
differently. But it is something that issuing a new RFC
cannot alone fix; we just have to live with that. I would
also note that the DAD process as a whole is not bullet
proof. Dropped packets, network partition, etc. can still
cause duplicated addresses to occur. The engineering
is to get the probability of that happening reasonably
low, and I think we are there.

You also suggested that 2461bis be changed to
clarify the on/off-link rules. I thought that most
of your clarified rules were good, though I did not
perform a detailed review so there may still be
issues. I note that others had question marks
on some of them. In any case, my big question
is to what extent you are (a) making an implementation
error less likely by emphasizing and reformulating
rules that 2461bis already has or (b) making some
actual new, tighter rules. I think most of it falls
under category (a). Is there some that are in (b)?

However, the amount of new text goes beyond what
we can put in under AUTH48. Given that the group
does not seem to unanimously believe that the
rules are missing from 2461bis, I feel reluctant
to go through the approval process once more.
It is more important to have a standard than to
achieve perfection.

However, I would like to make sure that the
implementation guidance is not lost. And it
may even be that after a discussion we realize
that the on-link rules need further work. Its
completely possible that we have to clarify
some part of ND even after 2461bis has been published;
the maintenance WG has been created in order to
deal with issues like that.

Here's what I would suggest:

1) We proceed with 2461bis publication.

2) We proceed with 2462bis publication.

3) You write one document that collects the
implementation guidance/clarified rules regarding
on/off link behaviour, and offer it for the new
IPv6 maintenance WG.

4) You write another document that collects other
implementation experience, and also offer it to the
same WG.

Jari


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