Re: WG ACTION: 2 weeks to discuss [LL70] DNAv4 normative or informative?

Well, I notice there's a difference in usage between
draft-ietf-dhc-dna-ipv4-07.txt and draft-ietf-zeroconf-ipv4-linklocal-14.txt:

draft-ietf-dhc-dna-ipv4-07.txt:

2.2.  Reachability Test

    If the host has a valid routable IPv4 address on the "most likely"
    point of attachment, the host will typically perform a reachability
    test, as described in this section.  The purpose of the reachability
    test is to confirm whether the host is connected to a network on
    which it has a valid routable IPv4 address.

draft-ietf-zeroconf-ipv4-linklocal-14.txt:

1.9.  When to configure a Link-Local IPv4 address

    [...]

    A "valid routable address" is a routable address that passes the
    reachability test described in section 2 of "Detection of Network
    Attachment (DNA) in IPv4" [DNAv4].

I read a subtle difference in meaning between these two text snippets: in
draft-ietf-dhc-dna-ipv4-07.txt, a valid routable address need not pass the
reachability test, while in draft-ietf-zeroconf-ipv4-linklocal-14.txt, a
routable address becomes a valid routable address once it has passed the
reachability test.  And, it's not clear draft-ietf-dhc-dna-ipv4-07.txt is
consistent in its use of the phrase "valid routable address".

Now, back to the real problem.  Unfortunately, it appears
draft-ietf-dhc-dna-ipv4-07.txt truly is a normative reference in
draft-ietf-zeroconf-ipv4-linklocal-14.txt as the text currently stands.  An
implementor has to read and understand draft-ietf-dhc-dna-ipv4-07.txt to
implement draft-ietf-zeroconf-ipv4-linklocal-14.txt.

We could try to finesse the problem as Erik suggests, by changing the
reference to the reachability test in draft-ietf-dhc-dna-ipv4-07.txt to be
advisory rather than mandatory.

Another way around the problem would be to copy the text about reachability
testing into draft-ietf-zeroconf-ipv4-linklocal-14.txt.  Seems like a lot of
text to insert that would cause yet another delay, but I don't have a better
suggestion.

I don't think removing the restriction against selecting a link-local
address when a usable routable address is available shold be removed.

- Ralph

At 01:26 AM 5/5/2004 +0200, Erik Guttman wrote:
>Please post discussion of this issue to the mailing list over the next two 
>weeks
>ending May 18, 2004.  In order to accept this issued, we will need a strong WG
>consensus given that this is very late in the process.
>
>Please see http://www.drizzle.org/~aboba/ZEROCONF/issues.html for a list of
>current issues and their status.
>
>[ll70]
>
>Description of Issue:           DNAv4 normative or informative?
>Submitter Name:                 Stuart Cheshire
>Submitter Email Address:        [email protected]
>Date first submitted:           04 May 04
>Reference:
>Comment Type ['t'ech|'e'dit]:   t
>Prio ['S' Must|1 should|2 may]: S
>Section:                        References
>Rationale/Explanation:
>Lengthy Description:
>
>[Stuart]
>
>>[DNAv4]   Aboba, B., "Detection of Network Attachment (DNA) in IPv4",
>>           draft-ietf-dhc-dna-ipv4-06.txt, Internet draft (work in
>>           progress), March 2004.
>
>Is this normative or informative?
>
>If ICMP is normative, this should be too.
>
>Or neither should be.
>
>[Erik]
>
>Why do you say that?  The only places we mention DNAv4 is in connection
>with DHCPv4.  If the IESG is happy with the informative reference
>categorization, so am I.  Adding this to the Normative reference section
>would delay publication of IPv4LL till DNAv4 is done.  I do not believe
>DNAv4 will complete within a year.
>
>[Stuart]
>
>I disagee.
>
>    For these
>    reasons, a host SHOULD NOT have both a valid routable address and an
>    IPv4 Link-Local address configured on the same interface.
>
>    A "valid routable address" is a routable address that passes the
>    reachability test described in section 2 of "Detection of Network
>    Attachment (DNA) in IPv4" [DNAv4].
>
>To implement this "SHOULD NOT" requirement, an implementation has to also
>implement [DNAv4] to determine what's a "valid routable address".
>
>Hence, normative reference (or the "SHOULD NOT" prohibition could be
>removed or refined to not depend on DNAv4).
>
>[Erik]
>
>Hmmm.  Do you realize you want to raise the bar for the publishing
>of this document beyond what the IESG has called for.  This change
>of category may well result in tens of months delay of publication of this 
>RFC.
>
>Can we change the 'is' verb in the second cited sentence to one
>that reads 'may be determined' and add some text from DNAv4 with
>an informative reference 'for further information'?  That is the
>way specific citations to 'upcoming work' are usually handled in
>order to avoid creating document dependencies.
>
>Requested Change:
>
>Move DNAv4 from informative to normative.