Shepherd writeup

(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?

Proposed Standard. This document documents a scheme used to provide
residual IPv4 service over IPv6 access networks.  Lightweight 4over6
is a solution designed specifically for complete independence between
the IPv6 subnet prefix and IPv4 address, either with or without IPv4
address sharing. This is accomplished by maintaining state for each
softwire (per-subscriber state) in the central lwAFTR along with a
hub-and-spoke forwarding architecture.

(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:

DS-Lite [RFC 6333] describes an architecture for transporting IPv4
packets over an IPv6 network.  This document specifies an extension to
DS-Lite called Lightweight 4over6 which moves the Network Address and
Port Translation (NAPT) function from the centralized DS-Lite tunnel
concentrator to the tunnel client located in the Customer Premises
Equipment (CPE).  This removes the requirement for a Carrier Grade NAT
function in the tunnel concentrator and reduces the amount of
centralized state that must be held to a per-subscriber level.  A
companion document describes the DHCPv6 options necessary for
provisioning of Lightweight 4over6. 

Working Group Summary:

The working group had active discussion on the draft and the current
text of the draft is representative of the consensus of the working
group. This document and the MAP-E document are closely related and it
led to a lot of friction in the working group.

Lightweight 4over6 is a solution designed specifically for complete
independence between IPv6 subnet prefix and IPv4 address with or
without IPv4 address sharing.  This is accomplished by maintaining
state for each softwire (per-subscriber state) in the central lwAFTR
and a hub-and-spoke forwarding architecture.  

MAP-E can also offer these capabilities or, alternatively, can provide
a reduction of the amount of centralized state using rules to express
IPv4/IPv6 address mappings.  This introduces an algorithmic
relationship between the IPv6 subnet and IPv4 address. This
relationship also allows the option of direct, meshed connectivity
between users.

Document Quality:

The document has received adequate review. The Document Shepherd has
no concerns about the depth or breadth of these reviews. There are
several interoperable implementations of the scheme and they have been
demonstrated and tested during the IETF meetings.


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

Suresh Krishnan is the document shepherd. Ted Lemon is the responsible

(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.

The document shepherd has reviewed the draft and finds that it is ready
to advance to the IESG. All issues that were raised in the working group
last calls have been addressed.

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

No. The document shepherd has no such concerns.

(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


(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.

There is significant overlap between the stateless softwire
solutions. The WG has discussed this overlap and the current document
set (along with the document dracks) are the result of working group
consensus to do so.

(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?


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

Not directly. There has been an IPR diclosure on a predecessor
document that this document replaced.

(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?

There is strong WG consensus behind this document. 

(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.)


(11) Identify any ID nits the Document Shepherd has found in this
document. (See and the Internet-Drafts
Checklist). Boilerplate checks are not enough; this check needs to be

No errors were found on the ID nits check. 

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


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


(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?


(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.


(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.


(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).

The document requires no IANA actions.

(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.


(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.