Shepherd writeup

Format reference:  RFC 4858, this is the current template for the Document (2/24/2012)

Status of shepherd's report:  Submitted to IESG for review. 

(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?

Type: Informational. 
Why is it the right type:  Describes the reason why the WG is allowing a choice of 
This informational document suggests allowing a choice of approach to
 allow multiple-levels between:
a) unique nicknames - giving a unique nickname to all TRILL switches in 
   L1/L2 areas, and having L1/L2 border switch advertise to the area which is available at 
  each level or having address space split between area/node-nickname 
b) aggregated nicknames - hiding nicknames used in each area and having 
border TRILL switches rewrite nicknames on ingress/egress TRILL packets. 

Understanding these choices is useful to deployments  - so this informational 
draft is useful to users, vendors, and researchers. 
(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
   Extending TRILL to multiple levels has challenges that are not
   addressed by the already-existing capability of IS-IS to have
   multiple levels.  One issue is with the handling of multi-destination
   packet distribution trees. Another issue is with TRILL switch
   nicknames.  There have been two proposed approaches.  One approach,
   which we refer to as the "unique nickname" approach, gives unique
   nicknames to all the TRILL switches in the multilevel campus, either
   by having the Level-1/Level-2 border TRILL switches advertise which
   nicknames are not available for assignment in the area, or by
   partitioning the 16-bit nickname into an "area" field and a "nickname
   inside the area" field.  The other approach, which we refer to as the
   "aggregated nickname" approach, involves hiding the nicknames within
   areas, allowing nicknames to be reused in different areas, by having
   the border TRILL switches rewrite the nickname fields when entering
   or leaving an area. Each of those approaches has advantages and

   This informational document suggests allowing a choice of approach in
   each area. This allows the simplicity of the unique nickname approach
   in installations in which there is no danger of running out of
   nicknames and allows the complexity of hiding the nicknames in an
   area to be phased into larger installations on a per-area basis.

Working Group Summary

  WG has worked on these solutions for 2+ years.  
  The WG consensus had no objections, and support of all key players with comments. 

  WG LC:

Document Quality

 Protocol extension has no implementation of this code. 
 Huawei plans to implement this function. 

 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?

  RTG-DIR review: 
    RTG-DIR Reviewer: Stig Venaas

 No other reviews required. 

  Document shepherd: Susan Hares
  Responsible AD: Alia Atlas 
  RTG-DIR reviewer: Stig Venaas 

(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.

Shepherd review:
(first review)
(-03.txt review) 
To be added 

Nits run: 
No errors except: 
  == There are 1 instance of lines with non-RFC6890-compliant IPv4 addresses
     in the document.  If these are example addresses, they should be changed.

This is an error in nits program.  The addresses are not IPv4 addresses. 

(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.

No wider reviews needed for informational. 

(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.

No additional 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.

Mingui Zhang:
Radia Perlman
Donald Eastlake:
Anoop Ghanwani

Hongjun Zhai -

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


The IPR disclosures have existed since the draft was adopted with the IPR disclosed in 2012. 

(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 discussions on multi-level occurred over 3 years - so the lack of contention is the result of lots discussions at IETF session on multi-level prior to drafts. 

(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 appeals pending. 

(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

Nits run: 
No errors except: 
  == There are 1 instance of lines with non-RFC6890-compliant IPv4 addresses
     in the document.  If these are example addresses, they should be changed.

This is an error in nits program.  The addresses are not IPv4 addresses. 

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

Informational document that is useful to users, vendors, TRILL WG, and 
any researchers examining the TRILL work.  No MIB, yang, media, or URI reviews. 

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

Normative - Ok. 
Informative - checking on four drafts 

   1) [DraftAggregated] - Bhargav Bhikkaji, Balaji Venkat Venkataswami,
         Narayana Perumal Swamy, "Connecting Disparate Data
         Center/PBB/Campus TRILL sites using BGP", draft-balaji-trill-over-ip-multi-level, Work In Progress.

This draft is individual draft, but it is a current work.  The AD should consider the status. 

All other informative references are TRILL WG drafts. 

(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.

No.  - it is informational only. 

(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).

No IANA related work.  Just an informational draft. 

(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.

Not applicable. 

(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.

Not applicable.