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?  Is this type of RFC indicated in the
title page header?

The document is targeted for Experimental.  This was the result of discussion in the working group.  The initial target had been a Proposed Standard, but the level of support for this by the end of the working group process was not high.  There have been good results from studies and deployments so far, and there is no reason to believe this would be harmful to deploy, so the working group believes that greater experimentation with PIE on the Internet should be encouraged, and that it might be a candidate for standardization later.

(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.

   Bufferbloat is a phenomenon where excess buffers in the network cause
   high latency and jitter. As more and more interactive applications
   (e.g. voice over IP, real time video streaming and financial
   transactions) run in the Internet, high latency and jitter degrade
   application performance. There is a pressing need to design
   intelligent queue management schemes that can control latency and
   jitter; and hence provide desirable quality of service to users. 

   This document presents a lightweight active queue management design,
   called PIE (Proportional Integral controller Enhanced), that can
   effectively control the average queueing latency to a target value.
   Simulation results, theoretical analysis and Linux testbed results
   have shown that PIE can ensure low latency and achieve high link
   utilization under various congestion situations. The design does not
   require per-packet timestamp, so it incurs very small overhead and is
   simple enough to implement in both hardware and software. 

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 

There were no matters of large controversy, though there have been some criticisms of PIE.  The IPR did not seem to be a blocking point for anyone, but some participants prefered algorithms free of IPR.  There are multiple algorithms that were proposed to the AQM working group, and there are still some developing.  Some aspects of the PIE design were critiqued, and there are some identified matters for future research, but there did not seem to be any disagreement that this is useful to publish at this time.  It is understood that this does not block other algorithms or improvements from happening.  The critical reviews are useful in understanding the differences with other algorithms, and making improvements to PIE while in experimental stage.

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?

Yes, there are multiple existing implementations, including in simulations, Linux, FreeBSD, and some may be based on description in the DOCSIS specification.  All of the implementation experience was helpful in improving the document quality and clarity when describing the algorithm.  A very thorough technical review was done by Bob Briscoe, and posted as a complete document itself.


  Who is the Document Shepherd? Who is the Responsible Area

Wesley Eddy ( is the document shepherd, and Mirja K├╝hlewind ( is the 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.

I have reviewed the complete document multiple times.  It is ready for the IESG.

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

No 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 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.

No concerns.  Going to Experimental is, it seems, agreeable to the working group.   There might have been concerns (e.g. based on Bob Briscoe's review, or IPR) if targeting Proposed Standard.

(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.

Yes.  There is IPR disclosed by Cisco, and tracked properly in the IETF system.  The working group has been aware of this.  After WGLC, 2 of the authors explicitly confirmed that all necessary disclosures have been made (the others did not reply).  All authors work for the same company (Cisco).

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

Yes.  The working group reviewed the IPR disclosure and understands it.

(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 consensus seems solid.

(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 threats or indications of discontent.

(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

There are only a couple very small formatting nits that will be fixed by the RFC Editor easily.  The nits reported about references seem to be spurious, and probably result from the use of an "other references" section which the RFC Editor could combine with the Informative References.

(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).

There are 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.