IPv6 Router Advertisement Flags Option
draft-ietf-ipv6-ra-flags-option-02

[Ballot discuss]
A length of 1 doesn't make sense to me.  RFC 2461 states:
      Length        8-bit unsigned integer.  The length of the option
                    (including the type and length fields) in units of
                    8 octets.  The value 0 is invalid.  Nodes MUST
                    silently discard an ND packet that contains an
                    option with length zero.
So if this option provided _no_ expansion bits, wouldn't the length be at least 2, and more likely 3 or more in practice?

[Ballot discuss]
o  MUST ignore the option if it is not the first option in the Router
      Advertisement

Are you sure you do not want to be liberal on receipt here? I understand making it a MUST to be the first option (strict in what you send), but if someone makes a mistake and puts it in as the second or third option, what is the harm in processing it?

And, as for the MUST for sending as the first option: Are you *sure* that there are no other options out there vying for this imporant position? Now or in the future? You can only have ONE like this (particularly if you are strict on receipt of the option).

[Ballot comment]
As specified, this option could be used even if all advertised capabilities are in bits 0 through 7.
The router advertisement flags option should only be used if the router is advertising capabilities
that are assigned bit 8 or higher by IANA.

In my opinion, some MUST/MUST NOT language is needed.

[Ballot discuss]
As specified, this option could be used even if all advertised capabilities are in bits 0 through 7.
I believe that would have a negative impact on interoperability.  The router advertisement
flags option should only be used if the router is advertising capabilities that are assigned
bit 8 or higher by IANA.

In my opinion, some MUST/MUST NOT language is needed.

[Ballot discuss]
As specified, this flag could be used even if all advertised capabilities are in bits 0 through 7.
I believe that would have a negative impact on interoperability.  The router advertisement
flags option should only be used if the router is advertising capabilities that are assigned
bit 8 or higher by IANA.

In my opinion, some MUST/MUST NOT language is needed.

[Ballot discuss]
As specified, this flag could be used even if all advertised capabilities are in bits 0 through 7.  I believe that would have a negative impact on interoperability.  The router advertisement flags option should only be used if the router is advertising capabilities that are assigned bit 8 or higher by IANA.

In my opinion, some MUST/MUST NOT language is needed.

[Ballot comment]
In the para
  The assignment of new RA flags in the RA option header and for the
  bits defined in the RA extension option defined in this document
  require standards action or IESG approval.

I think it would be good to reference RFC 2434.

[Ballot comment]
Based on Gen-ART Review by Joel Halpern:

  The document says that the length of the option is 1.  This is in
  multiples of 8 octets, so there is lots of room.  However, the text
  explicitly says that the length should be checked in case of future
  expansion.  It ought to specify what to do if the length is not 1.

IANA Last Call Comments:

IANA has questions.

Should the new router advertisement flag registry
live as a sub-registry of the icmpv6-parameters
registry? Or does it require its own full registry
page?


Action 1:

Upon approval of this document, the IANA will make
the following assignments in the "ICMPv6 TYPE
NUMBERS" registry located at

http://www.iana.org/assignments/icmpv6-parameters

sub-registry "IPv6 NEIGHBOR DISCOVERY OPTION FORMATS"

Type Description Reference
---- ----------- ---------
[TBA] RA Flags Extension Option [RFC-ipv6-ra-flags-option-01]


Action 2:

Upon approval of this document, the IANA will create
the following registry "IPv6 ND Router Advertisement
flags" located at

http://www.iana.org/assignments/TBD

Initial contents of this registry will be:

+---------------+---------------------------------------+-----------+
| RA Option Bit | Description | Reference |
+---------------+---------------------------------------+-----------+
| 0 | M - Managed Address Configuration | [RFC2461] |
| | Flag | |
| 1 | O - Other Configuration Flag | [RFC2461] |
| 2 | H - Mobile IPv6 Home Agent Flag | [RFC3775] |
| 3 | Prf - Router Selection Preferences | [RFC4191] |
| 4 | Prf - Router Selection Preferences | [RFC4191] |
| 5 | P - Neighbor Discovery Proxy Flag | [RFC4389] |
| 6-53 | R - Reserved; Available for |
[RFC-ipv6-ra-flags-option-01]
| | assignment | |
| 54-55 | Private Experimentation |
[RFC-ipv6-ra-flags-option-01]
+---------------+---------------------------------------+-----------+


NOTE: It would be better if the document used a
format more similar to IANA's registry formats.
In particular, don't use 'vertical ascii art'
to try to create columns.



We understand the above to be the only IANA Actions for this document.

My mail to the WG:

I have made my AD review of this document and found no
issues. The document will be moved forward.

By the way, note that the immediate need for this may be
less pressing now than a few months before. DNA WG
who was previously planning to use more bits is now
re-considering their solution for other reasons and
the new solution may not end up needing bits at all.
Also, I saw that the WGLC response came from just
a few persons. I'm not too happy about that but
perhaps it is acceptable in this case given that the
document is merely maintenance update to provide
more space for future extensions.

My mail to the chairs:

I have made my AD review on this document and it
looks good -- it will be moved forward. However,
there is one procedural issue that you should be aware
of, and handle it differently in the future. Both WG
chairs should never be authors in the same document,
and author/chair should not be handling the document
as a chair or shepherd. Or if they really both need
to be authors, then either someone else or the AD
needs to be brought in to handle the last calls, etc.

In this case I went through the discussion and saw
no problems, so I think we are fine. (Well, there
was not so much response for the WGLC or other
interest to begin with, but I think that's still enough
review for us to move forward with what is essentially
a maintenance task.)

Sorry for not catching this earlier -- I'm often seriously
behind on the ipv6 list discussions.

> (1.a)  Who is the Document Shepherd for this document?  Has the
>          Document Shepherd personally reviewed this version of the
>          document and, in particular, does he or she believe this
>          version is ready for forwarding to the IESG for publication?

Bob Hinden.    Yes.
>
>    (1.b)  Has the document had adequate review both from key WG members
>          and from key non-WG members?  Does the Document Shepherd have
>          any concerns about the depth or breadth of the reviews that
>          have been performed?

The document has been reviewed by the IPv6 w.g.  The version includes changes based on that discussion.  No concerns about quality of the document.
>
>    (1.c)  Does the Document Shepherd have concerns that the document
>          needs more review from a particular or broader perspective,
>          e.g., security, operational complexity, someone familiar with
>          AAA, internationalization or XML?

No.

>
>    (1.d)  Does the Document Shepherd have any specific concerns or
>          issues with this document that the Responsible Area Director
>          and/or the IESG should be aware of?  For example, perhaps he
>          or she is uncomfortable with certain parts of the document, or
>          has concerns whether there really is a need for it.  In any
>          event, if the WG has discussed those issues and has indicated
>          that it still wishes to advance the document, detail those
>          concerns here.  Has an IPR disclosure related to this document
>          been filed?  If so, please include a reference to the
>          disclosure and summarize the WG discussion and conclusion on
>          this issue.

None.

>
>    (1.e)  How solid is the WG consensus behind this document?  Does it
>          represent the strong concurrence of a few individuals, with
>          others being silent, or does the WG as a whole understand and
>          agree with it?

Reasonably solid concensus.  While there were comments on the first draft, there wasn't any negative comments received during the w.g. last call.

>    (1.f)  Has anyone threatened an appeal or otherwise indicated extreme
>          discontent?  If so, please summarise the areas of conflict in
>          separate email messages to the Responsible Area Director.  (It
>          should be in a separate email because this questionnaire is
>          entered into the ID Tracker.)

No.

>
>    (1.g)  Has the Document Shepherd personally verified that the
>          document satisfies all ID nits?  (See
>          http://www.ietf.org/ID-Checklist.html and
>          http://tools.ietf.org/tools/idnits/).  Boilerplate checks are
>          not enough; this check needs to be thorough.  Has the document
>          met all formal review criteria it needs to, such as the MIB
>          Doctor, media type and URI type reviews?

Yes.  I ran it through the id-nits tool.

>
>    (1.h)  Has the document split its references into normative and
>          informative?  Are there normative references to documents that
>          are not ready for advancement or are otherwise in an unclear
>          state?  If such normative references exist, what is the
>          strategy for their completion?  Are there normative references
>          that are downward references, as described in [RFC3967]?  If
>          so, list these downward references to support the Area
>          Director in the Last Call procedure for them [RFC3967].

Yes.  All references RFCs.  No normative issues.

>    (1.i)  Has the Document Shepherd verified that the document IANA
>          consideration section exists and is consistent with the body
>          of the document?  If the document specifies protocol
>          extensions, are reservations requested in appropriate IANA
>          registries?  Are the IANA registries clearly identified?  If
>          the document creates a new registry, does it define the
>          proposed initial contents of the registry and an allocation
>          procedure for future registrations?  Does it suggest a
>          reasonable name for the new registry?  See [RFC2434].  If the
>          document describes an Expert Review process has Shepherd
>          conferred with the Responsible Area Director so that the IESG
>          can appoint the needed Expert during the IESG Evaluation?

Yes.  The document requests a new assignment and a new registry to be set up.  This is described clearly.  The new registry is well defined and includes the procedure for new allocations (IESG approval or Standards action).

>
>    (1.j)  Has the Document Shepherd verified that sections of the
>          document that are written in a formal language, such as XML
>          code, BNF rules, MIB definitions, etc., validate correctly in
>          an automated checker?

N/A

>
>    (1.k)  The IESG approval announcement includes a Document
>          Announcement Write-Up.  Please provide such a Document
>          Announcement Write-Up?  Recent examples can be found in the
>          "Action" announcements for approved documents.  The approval
>          announcement contains the following sections:
>
>          Technical Summary
>              Relevant content can frequently be found in the abstract
>              and/or introduction of the document.  If not, this may be
>              an indication that there are deficiencies in the abstract
>              or introduction.

The IPv6 Neighbor Discovery Protocol's [1] Router Advertisement message contains an 8-bit field reserved for single-bit flags.  Several protocols have reserved flags in this field and others are preparing to reserve a sufficient number of flags to exhaust the field.

This document defines an option for the Router Advertisement message that expands the available number of flag bits by adding an additional 48 flag bits to NDP messages.

>
>          Working Group Summary
>              Was there anything in WG process that is worth noting?  For
>              example, was there controversy about particular points or
>              were there decisions where the consensus was particularly
>              rough?

The working group reviewed the initial version of this document, accepted it as an IPv6 w.g. document, and did a two week working group last call on.  The current draft resolves issues raised during the discussion and the working group last call.

>          Document Quality
>              Are there existing implementations of the protocol?  Have a
>              significant number of vendors indicated their plan to
>              implement the specification?  Are there any reviewers that
>              merit special mention as having done a thorough review,
>              e.g., one that resulted in important changes or a
>              conclusion that the document had no substantive issues?  If
>              there was a MIB Doctor, Media Type or other expert review,
>              what was its course (briefly)?  In the case of a Media Type
>              review, on what date was the request posted?

There are no known implementations of this protocol extension.  No feedback has been received on plans to implement.  It is expected that this option will be implemented by people implementing the protocols that will use the new flags.