Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Option for Dual-Stack Lite
draft-ietf-softwire-ds-lite-tunnel-option-10

[Ballot discuss]
This document is ready to move forward. However, there is one issue
that i would like to briefly discuss before recommending the final
approval of the RFC.

We have been pushing back in other cases when people defined both
FQDN and IP address information for the same configuration item in
DHCP. Why are two options and configuration mechanisms absolutely
necessary in this case? Wouldn't IP-address based configuration
suffice?

[Ballot comment]
Section 4 carries a couple of "MUST NOT" with respect to the DS-Lite
Name option. It would be well to describe what a receiver is supposed
to do in the event of a breach.

[Ballot discuss]
The meaning of "FQDN" seems to be underspecified. Is this limited to a "traditional domain name", i.e., a fully qualified domain name all of whose labels are "LDH labels" (as defined in RFC 5890)? Or can the HostName type be an "internationalized domain name", i.e., a DNS domain name at least one of whose labels is a "U-label" or "A-label" (as defined in RFC 5890)? If this document inherits its definition of FQDN from Section 8 of RFC 3315, then it would be good to make that clear and specify that internationalized labels from IDNs need to be represented as A-labels.

[Ballot comment]
1) in the INtroduction, the first mention of AFTR should be spelled out and given a reference.
(I am aware it is spelled out in the Abstract, but I think ti should also be spelled out here.

2) it would be good to identify the specific registry in the IANA registries (e.g., by URL), and to provide the added values formatted to match the existing registry.

[Ballot discuss]
This document appears to be in good shape. I have a few clarifying questions

1) in section 5,
The server MUST provide a way to configure the OPTION_DS_LITE_ADDR,
  and SHOULD allow the operator to enter a Fully Qualified Domain Name,
  upon which the server performs DNS Resolution to assemble its
  OPTION_DS_LITE_ADDR contents.
does the server really perform DNS resolution when an FQDN is entered?

what if the client and server have access to different DNS servers?
Couldn't you run into a situation where the server cannot resolve the FQDN but the client could?
or vice-versa?

I see there is a DNS_SERVERS option, but this would presumably be configured from the DHCP server perspective.
Could the client have difficulty reaching the specified DNS servers, due to firewalls, NATs, or routing?
The text doesn't say the DNS_SERVERS option must contain servers reachable by both server and client, and I don't know whether it is reasonabe to require that knowledge at time of configuration, and for it to be true at time of use.

2) in a related question,
If the server is configured with an FQDN as the tunnel endpoint
  locator, the configured FQDN value MUST contain a resolvable Fully
  Qualified Domain Name, having appropriate delegations from the root,
  and having a AAAA record locating the Softwire Concentrator.
what happens if the client and server have different capabilities to get a AAAA record,
maybe because of a NAT at IPvX boundaries?

3) in section 6,
  A client that supports B4 functionality of DS-Lite (defined in
  [I-D.softwire-ds-lite-04]) MUST include OPTION_DS_LITE_ADDR on its
  OPTION_ORO, and MAY include OPTION_DS_LITE_NAME at its option and
  ability.

Is this a new compliance requirement for B4s that could render existing compliant B4 implementations non-compliant?

[Ballot discuss]
This is a DISCUSS DISCUSS:

3.  The Dual-Stack Lite Address DHCPv6 Option

  The client validates the DS-Lite Address option by confirming the
  option is of 16 octets in length or greater.  The client MUST ignore
  any tunnel-endpoint-addr shorter than 16 octets.  In the event the
  option is greater than 16 octets in length, only the first 16 octets
  are interpreted.

Is there any good reason to tolerate any value of this option with length != 16?

IANA comments:

Upon approval of this document, IANA will make the following assignments
in the DHCPv6 Option Codes registry at
http://www.iana.org/assignments/dhcpv6-parameters/dhcpv6-parameters.xml

Value Description Reference
TBD1 OPTION_DS_LITE_ADDR [RFC-ietf-softwire-ds-lite-tunnel-option-03]
TBD2 OPTION_DS_LITE_NAME [RFC-ietf-softwire-ds-lite-tunnel-option-03]

We understand the above to be the only actions required by this document.

(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?

Dave Ward is the Shepherd. He has
reviewed the documents and believes they ready for publication.

(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?

We saw evidence of extensive review on the mailing list. The documents
has been presented in softwires, v6ops, and dhc working groups.

(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 concerns.

(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.

This is strictly a protocol specification. We believe that an
operational document discussing some of the various tradeoffs and
choices when deploying DS-Lite would be valuable.

We know of no IPR disclosures related to this document.

(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?

Some individuals have expressed concern that the document doesn't go
into enough depth on certain subjects, such as MTU handling, but in the chair's opinion most
of those subject are general issues, not specific to DS-lite. Aside of this,
the document has strong support in the WG.

(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 theInternet-Drafts Checklist
andhttp://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?

Passes nits, no need for doctor reviews.

(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].

Clean.

(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 [RFC5226]. 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?

There is a request for one dhcp option code point in the IANA
considerations section of the DHCP option document and a request for a
well known IPv4 prefix in the DS-Lite document.

(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?

There is no formal language in the document.

(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.

DHCP option


This document specifies two DHCPv6 options which are meant to be used
by a Dual-Stack Lite client (Basic Bridging BroadBand element, B4) to
discover its Address Family Transition Router (AFTR) address.

DS-Lite

This document revisits the dual-stack model and introduces the dual-
stack lite technology aimed at better aligning the costs and benefits
of deploying IPv6. Dual-stack lite enables a broadband service
provider to share IPv4 addresses among customers by combining two
well-known technologies: IP in IP (IPv4-in-IPv6) and Network Address
Translation (NAT).


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?

This document was discussed in depth and well-reviewed. There is some
disagreement over small details, but overall WG consensus is strong to
publish this document.

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 multiple, independent, interoperable implementations of this
protocol today. Several service providers have announced plans to deploy
or interest in deploying.