Issues and Recommendations with Multiple Stateful DHCPv6 Options
draft-ietf-dhc-dhcpv6-stateful-issues-12

[Ballot comment]
For the sake of documenting Ron's (OPS DIR) review...
Nits:

The Nit-checker complains about a malformed reference on line 606. It complains because this document has no reference [17]. However, the text in question is UPDATING RFC 3315, which does have a reference [17]. So, I recommend that we let this nit slide and let the RFC editor figure out what to do about it.

[Ballot comment]
These comments are put in terms of MUST/SHOULD/MAY, but really it is about the meaning you are trying to convey; the particular 2119 terminology is not the main point.

4: I admit to be a little baffled by some of the language in the top level of this section. You say:

  Resetting the state machine and continuing to send Solicit messages
  may result in the client never completing DHCP and is generally not
  considered a good solution.  It can also result in a packet storm if
  the client does not appropriately rate limit its sending of Solicit
  messages or there are many clients on the network.

Cool. That seems like a real problem that needs to be kept in mind when doing implementation. So why then do you follow this with:
 
  Client
  implementors that follow this approach, are strongly advised to
  implement the updates to RFC-3315 specified in [RFC7083].
 
"Strongly advised"? Sounds like they MUST implement the 7083 updates, lest they fail to interoperate or cause serious damage to the net. If there are ways to avoid a packet storm without the 7083 update, but you had better know what you are doing, then that means that you SHOULD implement the 7083 updates. Why "strongly advised"?

You then go on to explain the problems with separate DHCP sessions, and explain why single session is mostly better (with some caveats), but then conclude with:

  While all approaches have their own pros and cons, we recommend and
  focus on approach 3 for this document because it is deemed to work
  best for common cases of the mixed use of IA_NA and IA_PD.  But this
  document does not exclude other approaches.

"recommend and focus on approach 3"? How about, "approach 3 SHOULD be used" or "approach 3 is RECOMMENDED". If there are reasons to choose one of the other approaches, you had better know why you've chosen them, but that's exactly what SHOULD/RECOMMENDED means.

Any reason for this low-key mushy way of talking in this section?

4.1:

"MUST be prepared to handle" strikes me funny. Any reason not to simply say "MUST handle" or "MUST accept"?

OLD
  Servers MUST return the Status Code option of NoAddrsAvail
  encapsulated in an IA_NA/IA_TA options and not as a top-level Status
  Code option of NoAddrsAvail when no addresses will be assigned (1 in
  the above list).

The "not" in there seems like something that shouldn't be missed. Can I suggest strengthening it as follows?

NEW
  Servers MUST return the Status Code option of NoAddrsAvail
  encapsulated in an IA_NA/IA_TA options and MUST NOT return it as a
  top-level Status Code option of NoAddrsAvail when no addresses will
  be assigned (1 in the above list).

4.2:

OLD
      - MAY display any associated status message(s) to the user.

The "MUST ignore" seems to have an implicit "for protocol processing purposes". Displaying the status to the user is not protocol processing, and therefore I think the MAY (which implies a protocol option) isn't quite right (and wasn't quite right in 3315 either). Simply saying, "Of course, a client can display any associated status message(s) to the user." seems better. Similarly with the last paragraph of 4.2 and the first paragraph of 4.4.5.

4.4.1 and 4.4.2, last paragraph of each: Don't change these blindly; this is just a question: Is there a reason the "should"s and the "may" are not "SHOULD"s and "MAY"? These sure sound like interoperability claims.

4.6: Isn't "It is recommended that a client SHOULD NOT send" redundant? How about just "A client SHOULD NOT send"?

[Ballot comment]
I was able to follow this document fairly well, except in this text:

  The single session and state machine allows the client to use the
  best configuration it is able to obtain from a single DHCP server
  during the configuration exchange.  Note, however, that the server
  may not be configured to deliver the entire configuration requested
  by the client.  In that case the client could continue to operate
  only using the configuration received, even if other servers can
  provide the missing configuration. 
 
I THINK I'm getting tripped up on "could continue to operate". Is this intended to say "_will_ continue to operate only using the configuration received"? "Could" says, to me, that the client might do that, or might do something else that's not specified, that I saw. But I'm guessing.

Otherwise, for a document that's updating a bunch of RFCs, this draft was very clear.

IESG/Authors/WG Chairs:

IANA has reviewed draft-ietf-dhc-dhcpv6-stateful-issues-11, which is currently in Last Call, and has the following comments:

We understand that,  upon approval of this document, there are no IANA Actions that need completion.

While it is helpful for the IANA Considerations section of the document to remain in place upon publication, if the authors prefer to remove it, IANA doesn't object.

If this assessment is not accurate, please respond as soon as possible.

The following Last Call announcement was sent out:

From: The IESG
To: IETF-Announce
CC:
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (Issues and Recommendations with Multiple Stateful DHCPv6 Options) to Proposed Standard


The IESG has received a request from the Dynamic Host Configuration WG
(dhc) to consider the following document:
- 'Issues and Recommendations with Multiple Stateful DHCPv6 Options'
  as Proposed Standard

The IESG plans to make a decision in the next few weeks, and solicits
final comments on this action. Please send substantive comments to the
ietf@ietf.org mailing lists by 2015-03-04. Exceptionally, comments may be
sent to iesg@ietf.org instead. In either case, please retain the
beginning of the Subject line to allow automated sorting.

Abstract


  The Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
  specification defined two stateful options, IA_NA and IA_TA, but did
  not anticipate the development of additional stateful options.
  DHCPv6 Prefix Delegation added the IA_PD option, which is stateful.
  Applications that use IA_NA and IA_PD together have revealed issues
  that need to be addressed.  This document updates RFC 3315 and RFC
  3633 to address these issues.




The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-dhc-dhcpv6-stateful-issues/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-dhc-dhcpv6-stateful-issues/ballot/


No IPR declarations have been submitted directly on this I-D.

As required by RFC 4858, this is the current template for the Document
Shepherd Write-Up.

Changes are expected over time. This version is dated 24 February
2012.

Write-up for draft-ietf-dhc-dhcpv6-stateful-issues-11

(1) What type of RFC is being requested (BCP, Proposed Standard,
Internet Standard, Informational, Experimental, or Historic)?  Why
is this the proper type of RFC?  Is this type of RFC indicated in the
title page header?

  Standards track. This I-D proposes several updates to RFC3315 and
  RFC3633 (both are proposed standard), so this is the right type. The
  intended type is clearly indicated in the page header.

(2) 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

  DHCPv6 (RFC3316) was not written with the initial expectation that
  additional stateful DHCPv6 options would be developed. Prefix
  Delegation (RFC3633) introduced the IA_PD option, which is stateful.
  Implementation experience of the CPE model described in RFC 7084 has
  shown multiple issues with the DHCPv6 protocol in supporting multiple
  stateful options. This document updates RFC 3315 and RFC 3633 to
  address the identified issues. It is also considered an essential
  milestone in the RFC3315bis work.

Working Group Summary

  This draft was around in the DHC for a long time (WG item since May
  2012) and was discussed extensively (248 mails posted to the dhc
  list the last time I checked, with many more off-line and on the
  dhcpv6bis list). It was started as a spin-off from RFC7084 work
  (Basic requirements for IPv6 CE routers). This I-D went through
  three WGLCs. The first one (for -03) in Jan. 2013 failed due to
  lack of responses. The document went into hibernation for a while,
  and we had a second WGLC in Feb. 2014. Some feedback and support was
  received, but chairs decided that it's not sufficient for such an
  important I-D (it tweaks several major mechanisms in DHCPv6, so we
  felt that the bar is set higher than average). Finally, the third
  WGLC in Dec. 2014 passed. There was never any opposition to this
  draft. The challenge was to persuade people to express their support.

Document Quality

  This I-D clarifies and corrects several inconstencies in DHCPv6.
  The ambiguity in the RFC3315 and RFC3633 causes some interop
  problems. Several of the issues addressed were raised during
  interop events.

  This document is of high quality. It was extensively reviewed by
  matter experts that are involved in several independent
  implementations. This I-D is also considered an essential step in
  the 3315bis work, so it received further reviews and discussions in
  the dhcpv6bis team.

  There are partial implementations of this proposal, but all major
  vendors that participated are planning to implement this proposal.
  Many clarifications came out as a result of the interop testing.
  One could even say that many parts of this I-D are implemented for
  many years now. Prompt adoption upon publication is expected.

Personnel

  Who is the Document Shepherd? Who is the Responsible Area
  Director?

  Tomek Mrugalski is the shepherd. Ted Lemon is the responsible AD.

(3) Briefly describe the review of this document that was performed by
the Document Shepherd.  If this version of the document is not ready
for publication, please explain why the document is being forwarded to
the IESG.

  I thoroughly reviewed this document three times:
  http://www.ietf.org/mail-archive/web/dhcwg/current/msg16059.html (-09)
  http://www.ietf.org/mail-archive/web/dhcwg/current/msg13797.html (-03)
  http://www.ietf.org/mail-archive/web/dhcwg/current/msg12591.html (-00)

  I also participated in many discussions related to it (face to face,
  on dhc list, on dhcpv6bis, and off the list). I checked all changes
  since -09. This document is ready in my opinion and should be
  published.

(4) Does the document Shepherd have any concerns about the depth or
breadth of the reviews that have been performed?

  No. This document was thoroughly reviewed and it should be published.

(5) Do portions of the document need review from a particular or from
broader perspective, e.g., security, operational complexity, AAA, DNS,
DHCP, XML, or internationalization? If so, describe the review that
took place.

  This I-D is DHCPv6-centric, so DHC is the proper WG for this work.
  It was reviewed extensively. There is no need for any outside area
  review.

(6) Describe any specific concerns or issues that the Document Shepherd
has 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.

  I have no such concerns.

(7) Has each author confirmed that any and all appropriate IPR
disclosures required for full conformance with the provisions of BCP 78
and BCP 79 have already been filed. If not, explain why.

  Yes, all authors confirmed in writing. There are no IPRs, existing or
  outstanding.

(8) Has an IPR disclosure been filed that references this document?
If so, summarize any WG discussion and conclusion regarding the IPR
disclosures.

  No.

(9) 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?

  The consensus is pretty solid. This document is active in the DHC
  for quite a long time, so the support was expressed over multiple
  occasions. This draft is essentially a collection of small tweaks
  to the DHCPv6 protocol. It was a sort of judgment call to what to
  include in this draft and what to postpone to dhcpv6bis. There were
  infrequent suggestions to include more in stateful-issues, but
  the consensus is rather strong in this case.

(10) 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 publicly available.)

  No.

(11) Identify any ID nits the Document Shepherd has found in this
document. (See http://www.ietf.org/tools/idnits/ and the Internet-Drafts
Checklist). Boilerplate checks are not enough; this check needs to be
thorough.

  There are 2 idnit comments and both are bogus. The first one is
  about the draft using pre-RFC5378 disclaimer. This draft uses parts
  of the RFC3315 that was published in 2003 (before 5378) and the
  I-D authors didn't manage to get approval of all original RFC
  authors, so the dislaimer is correct.

  Second issue reported is about a [17] reference in line 606. That
  is correct as well, as the whole section 4.4.5 is a replacement text
  for section 18.1.8 of RFC3315. [17] is a valid reference in RFC3315.

(12) Describe how the document meets any required formal review
criteria, such as the MIB Doctor, media type, and URI type reviews.

  No such review is required.

(13) Have all references within this document been identified as
either normative or informative?

  Yes.

(14) 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 plan for their completion?

  No. All normative references are to published RFCs only.

(15) Are there downward normative references references (see RFC 3967)?
If so, list these downward references to support the Area Director in
the Last Call procedure.

  No. There are no such references.

(16) Will publication of this document change the status of any
existing RFCs? Are those RFCs listed on the title page header, listed
in the abstract, and discussed in the introduction? If the RFCs are not
listed in the Abstract and Introduction, explain why, and point to the
part of the document where the relationship of this document to the
other RFCs is discussed. If this information is not in the document,
explain why the WG considers it unnecessary.

  Yes. This document will update RFC3315 and RFC3633. That is clearly
  stated on the front page and in the abstract. The nature of those
  changes is discussed in the Introduction.

(17) Describe the Document Shepherd's review of the IANA considerations
section, especially with regard to its consistency with the body of the
document. Confirm that all protocol extensions that the document makes
are associated with the appropriate reservations in IANA registries.
Confirm that any referenced IANA registries have been clearly
identified. Confirm that newly created IANA registries include a
detailed specification of the initial contents for the registry, that
allocations procedures for future registrations are defined, and a
reasonable name for the new registry has been suggested (see RFC 5226).

  This document does not require any IANA actions. That is clearly
  stated in the IANA considerations section.

(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find
useful in selecting the IANA Experts for these new registries.

  There are no such registries defined.

(19) Describe reviews and automated checks performed by the Document
Shepherd to validate sections of the document written in a formal
language, such as XML code, BNF rules, MIB definitions, etc.

  There are no such sections, so automated checks are not necessary.