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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)? 

Informational RFC

Why is this the proper type of RFC? 

The document does not standardize or provide guidance on best current practise
of the use of ECN. It summarizes the potential benefits of finally deploying
ECN for transport protocols.

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:

This document is mostly a list of demonstrated and expected benefits to 
transport protocols by using ECN. It highlights points that are most 
visible to the application layer within the end-points. It then goes on 
discussing specific deployment scenarios of ECN in a network, and the 
internet at scale. 

The key benefits of running ECN are summarized as
o) Improved throughput                                 
o) Reduced Head-of-Line blocking                       
o) Reduced probability of RTO Expiry                   
o) Applications that do not retransmit lost packets    
o) Making incipient congestion visible                 
o) Opportunities for new transport mechanisms          

Working Group Summary:

The document was brought to the working group to highlight and underline the
many benefits ECN can have, if deployed at scale. During the WG discussions, the
character of the draft changed slightly, from looking only at the positive 
implications to also describe potential drawbacks and pitfalls.

The intention of this document though is less technical in nature, and instead is 
intended as a reference as to why deploying ECN at this time would be sensible. 
It aims to be a manifest that can be shown to decision-makers who quickly need
to understand the key benefits of ECN, with a high level of technical guidance.

Document Quality:

Are there existing implementations of the protocol? 

The document is agnostic of any specific implementation, and rather argues
about the architectural model (well, as supported by the IP protocol) to use
ECN. Implementations of ECN in TCP (RFC3168) are in wide-spread use, but with
the ECN capabilities disabled, or only passively enabled. Arguably, the document
helped to persuade decision-maker at a large vendor to actively start deploying 

Have a significant number of vendors indicated their plan to implement the 

The document aims to achieve just that - to drive the adoption rate of a well
known and available protocol by vendors up.

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? 

There were lively discussions in the AQM working group around this document.
First, to not only speak exclusively about the positive aspects, but also 
mention potential issues. Second, that document had widespread support in the WG
as it preaches to the choir - but word has to be spread about ECN to a larger


Who is the Document Shepherd? 

Richard Scheffenegger, AQM WG co-chair

Who is the Responsible Area Director?

Martin Stiemerling, Transport 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 document had thorough discussions in the WG sessions. Both content and 
wording have been honed, as witnessed also by the sheperd. There are no 
unresolved issues which would preclude this from being forwarded to the 

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

No; the final few iterations were all about word-smithing, and to put the 
document into a form that is expected to have the most impact at the 
intended audience.

(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 


(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 disclosures.


(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 concensus on the document, as the entire WG strongly 
thinks ECN will allow the internet to further improve. But as ECN requires 
multilateral support to play out, it was found that the time is now for a 
high level overview document like this to become a referencable RFC.

(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 thorough.

Some references need updating (some in RFC editor queue) as they are in 
".bis" state, or pre-RFC references.

There is one intentional downref reference to RFC1349 - as some devices appear to
still be running code that does not comply with RFC2474.

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

No formal reviews necessary.

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

Yes, all references are accounted for, and are split in normative and 
informative, as appropriate. 

(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?

Yes - some references are in ".bis" state (one has become RFC already). As 
the document does not standardize new protocols, but rather encourage the 
deployment of existing mechanisms, the document may not need to be delayed 
until these references have been posted as full RFCs.

(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 

RFC1349 - as an example where existing gear has not been updated to comply 
with the current RFC2474 (both are in the same paragraph).

(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).

No IANA actions required, no protocol updates are part of the document.

(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.

This RFC does not have any sections containing formal language, thus this is
not applicable.