Shepherd writeup

>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.
>(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?  

The document helps to clarify service model related concepts and 
establish a common categorization rather than any specific mechanism.

>Is this type of RFC indicated in the
>title 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
>  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.

This document describes service models including scope and purpose as 
used within the IETF, and shows where a service model might fit into a 
Software Defined Networking architecture. It also clarifies what a 
service model is not, and dispels some common misconceptions.
>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?

There was debate on the "network service model" concept in RFC 8199 . 
This was solved by coordinating the cross WG discussion with NETMOD 
during both the WG adoption call and WG LC.

>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?

This document has received extensive input and review. It has already 
been used to direct L2SM and L3SM work.
>  Who is the Document Shepherd? 

Tianran Zhou
>  Who is the Responsible Area
>  Director?

Warren Kumari will normally serve as 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.

The Shepherd reviewed the draft multiple times and ensured that 
appropriate review was conducted in and out of the WG.

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


>(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.


>(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.

This document provides a taxonomy for YANG models, especially for 
service models. It's expected that the classification boundaries are at 
times blurry, and the classification criteria may change over time. 
For some existing YANG modules, it's hard to find one corresponding 
category. The information given by this document is a starting point 
and shows current knowledge/experience on service models used within 

>(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


>(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?  

Solid among interested WG participants.

>(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

The document passed ID nits.

>(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).

This document makes no requests for IANA action.

>(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.