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Overview of Pre-Congestion Notification Encoding
RFC 6627

Revision differences

Document history

Date Rev. By Action
2018-12-20
09 (System)
Received changes through RFC Editor sync (changed abstract to 'The objective of Pre-Congestion Notification (PCN) is to protect the quality of service (QoS) of inelastic …
Received changes through RFC Editor sync (changed abstract to 'The objective of Pre-Congestion Notification (PCN) is to protect the quality of service (QoS) of inelastic flows within a Diffserv domain. On every link in the PCN-domain, the overall rate of PCN-traffic is metered, and PCN-packets are appropriately marked when certain configured rates are exceeded. Egress nodes provide decision points with information about the PCN-marks of PCN-packets that allows them to take decisions about whether to admit or block a new flow request, and to terminate some already admitted flows during serious \%pre-congestion.

The PCN working group explored a number of approaches for encoding this pre-congestion information into the IP header. This document provides details of those approaches along with an explanation of the constraints that apply to any solution. This document is not an Internet Standards Track specification; it is published for informational purposes.')
2015-12-31
09 Jean Mahoney Closed request for Last Call review by GENART with state 'No Response'
2015-10-14
09 (System) Notify list changed from pcn-chairs@ietf.org, draft-ietf-pcn-encoding-comparison@ietf.org to (None)
2012-07-19
09 (System) RFC published
2012-03-29
09 Martin Stiemerling Responsible AD changed to Martin Stiemerling from David Harrington
2012-03-19
09 Cindy Morgan State changed to RFC Ed Queue from Approved-announcement sent
2012-03-19
09 (System) IANA Action state changed to No IC
2012-03-19
09 Cindy Morgan State changed to Approved-announcement sent from Approved-announcement to be sent
2012-03-19
09 Cindy Morgan IESG has approved the document
2012-03-19
09 Cindy Morgan Closed "Approve" ballot
2012-03-19
09 Cindy Morgan Ballot approval text was generated
2012-03-19
09 Cindy Morgan Ballot writeup was changed
2012-03-19
09 David Harrington State changed to Approved-announcement to be sent from IESG Evaluation::AD Followup
2012-03-19
09 David Harrington Ballot approval text was generated
2012-03-19
09 David Harrington Ballot approval text was generated
2012-03-19
09 David Harrington Ballot approval text was generated
2012-03-19
09 David Harrington Ballot approval text was generated
2012-03-19
09 Adrian Farrel
[Ballot comment]
Thank you for addressing my Discuss issues and Comments.

Note that the revised text in Section 5 (for which, thanks) is
missing blank …
[Ballot comment]
Thank you for addressing my Discuss issues and Comments.

Note that the revised text in Section 5 (for which, thanks) is
missing blank lines between the paragraphs.
2012-03-19
09 Adrian Farrel [Ballot Position Update] Position for Adrian Farrel has been changed to No Objection from Discuss
2012-03-09
09 Russ Housley [Ballot Position Update] Position for Russ Housley has been changed to No Objection from Discuss
2012-03-09
09 David Harrington Ballot writeup was changed
2012-03-08
09 (System) Sub state has been changed to AD Followup from Revised ID Needed
2012-03-08
09 Georgios Karagiannis New version available: draft-ietf-pcn-encoding-comparison-09.txt
2012-03-08
08 Stewart Bryant [Ballot Position Update] Position for Stewart Bryant has been changed to No Objection from Discuss
2012-03-06
08 David Harrington State changed to IESG Evaluation::Revised ID Needed from IESG Evaluation::AD Followup
2012-03-01
08 Samuel Weiler Request for Last Call review by SECDIR Completed. Reviewer: Steve Hanna.
2012-03-01
08 Cindy Morgan State changed to IESG Evaluation::AD Followup from Waiting for AD Go-Ahead
2012-03-01
08 Russ Housley
[Ballot discuss]
The Gen-ART Review by Pete McCann on 28-Feb-2012 raised an
  inconsistency that needs to be resolved.

  Section 3.3.3.4 says:
  > …
[Ballot discuss]
The Gen-ART Review by Pete McCann on 28-Feb-2012 raised an
  inconsistency that needs to be resolved.

  Section 3.3.3.4 says:
  >
  > With the normal mode, the ECN field of the inner header is copied
  > to the ECN field of the outer header on encapsulation (like the
  > limited functionality option in Section 3.3.3.1).
  >
  The limited functionality option says to set the outer header to
  not-ECT.  This seems to contradict the above statement.
2012-03-01
08 Russ Housley
[Ballot comment]
The Gen-ART Review by Pete McCann on 28-Feb-2012 included some
  editorial suggestions that deserve consideration

  (1) Section 3.3.3.3 says:
  > …
[Ballot comment]
The Gen-ART Review by Pete McCann on 28-Feb-2012 included some
  editorial suggestions that deserve consideration

  (1) Section 3.3.3.3 says:
  >
  > ... full-functionality option in Section 3.3.2.2.
  >
  I think you meant "Section 3.3.3.2".  One other place in this
  paragraph needs this correction too.

  (2) Section 4.2 says:
  >
  > The problem with 3-in-1 encoding is that the 10-codepoint does
  > not survive decapsulation with the tunneling options in
  > Section 3.3.2.1 - 3.3.2.3.
  >
  Again, you meant 3.3.3.1 - 3.3.3.3
2012-03-01
08 Russ Housley [Ballot Position Update] New position, Discuss, has been recorded for Russ Housley
2012-03-01
08 Stewart Bryant
[Ballot discuss]
This is a discuss discuss, in that I would like to discuss with the IESG whether this work should more properly be classified …
[Ballot discuss]
This is a discuss discuss, in that I would like to discuss with the IESG whether this work should more properly be classified as experimental.
2012-03-01
08 Stewart Bryant [Ballot Position Update] New position, Discuss, has been recorded for Stewart Bryant
2012-03-01
08 Gonzalo Camarillo [Ballot Position Update] New position, No Objection, has been recorded for Gonzalo Camarillo
2012-02-29
08 Wesley Eddy [Ballot Position Update] New position, No Objection, has been recorded for Wesley Eddy
2012-02-29
08 Ron Bonica [Ballot Position Update] New position, No Objection, has been recorded for Ronald Bonica
2012-02-29
08 Robert Sparks [Ballot Position Update] New position, No Objection, has been recorded for Robert Sparks
2012-02-29
08 Adrian Farrel
[Ballot discuss]
Section 3.2.3

I cannot reconcile the text in option (1) that says:

with the conclusion of the section that says:

  Option (1) …
[Ballot discuss]
Section 3.2.3

I cannot reconcile the text in option (1) that says:

with the conclusion of the section that says:

  Option (1) seems to be the most viable and efficient solution.

If it is the intention of the PCN working group to be "PCN for IP-only
networks" then I do think this could be s[elled out. OTOH, if MPLS is
in scope, then surely option (1) is impractical.

Note that draft-ietf-pcn-3-in-1-encoding makes a specific statement
about applicability only to IP.

---

What does "Primarily" mean in this context?

I would like you to replace the passive voice in Section 4.5 so I can
tell who made the decision!

Additionally, I would like to understand why there are other PCN working
group documents for other encodings (draft-ietf-pcn-3-state-encoding,
draft-ietf-pcn-psdm-encoding) if this section represent a full statement
of the WG's decisions.

---

I'm afraid I found the conclusion in Section 5 particularly
impenetrable.

Could you:
- Break out "what we did in this document" as a separate paragraph.
- Make a definitive statement about what the WG has concluded.
- Place the summary of the reasons for the conclusion as a third
  paragraph.
2012-02-29
08 Adrian Farrel
[Ballot comment]
In Section 1 

  This
  requires at least three different codepoints for not-marked PCN
  traffic, PCN traffic re-marked by the threshold-marker, …
[Ballot comment]
In Section 1 

  This
  requires at least three different codepoints for not-marked PCN
  traffic, PCN traffic re-marked by the threshold-marker,
  and PCN traffic re-marked by the excess-traffic-marker.

Please insert a colon after "codepoints" in order to fix the meaning.

---

In Section 1

  This
  document summarizes these issues for historical purposes.

Do you want to publish this as a Historic RFC?

---

Section 3

  The Differentiated Services (DS) field is chosen for the encoding of
  PCN marks.

This use of the passive voice is not helpful!

- Has the choice already been made? If so give a reference.
- Does this document document the choice being made? If so give a
  forward pointer or explanation.
- Or is this just commentary? :-)

---

I think Section 3.1 makes [RFC0793], [RFC2474], and [RFC3168] into
normative references. 3.3.1 reinfotces that for [RFC3168].

Section 3.3 and 3.3.2 appear to make [RFC4774] normative.

---

Section 3.3.3.4 uses "CU" before it is explained in Seciton 4 and
defined in Section 4.3

---

Section 4

  Figure 7 summarizes these PCN encodings. as summarized 
  in Figure 7.

:-)
2012-02-29
08 Adrian Farrel [Ballot Position Update] New position, Discuss, has been recorded for Adrian Farrel
2012-02-28
08 Peter Saint-Andre [Ballot Position Update] New position, No Objection, has been recorded for Peter Saint-Andre
2012-02-27
08 Stephen Farrell [Ballot Position Update] New position, No Objection, has been recorded for Stephen Farrell
2012-02-23
08 (System) State changed to Waiting for AD Go-Ahead from In Last Call.
2012-02-18
08 Samuel Weiler Request for Last Call review by SECDIR is assigned to Steve Hanna
2012-02-18
08 Samuel Weiler Request for Last Call review by SECDIR is assigned to Steve Hanna
2012-02-17
08 Amanda Baber We understand that this document doesn't require any IANA actions.
2012-02-10
08 Jean Mahoney Request for Last Call review by GENART is assigned to Pete McCann
2012-02-10
08 Jean Mahoney Request for Last Call review by GENART is assigned to Pete McCann
2012-02-09
08 David Harrington Placed on agenda for telechat - 2012-03-01
2012-02-09
08 David Harrington [Ballot Position Update] New position, Yes, has been recorded for David Harrington
2012-02-09
08 David Harrington Ballot has been issued
2012-02-09
08 David Harrington Created "Approve" ballot
2012-02-09
08 Cindy Morgan Last call sent
2012-02-09
08 Cindy Morgan
State changed to In Last Call from Last Call Requested.

The following Last Call Announcement was sent out:

From: The IESG
To: IETF-Announce
CC:
Reply-To: …
State changed to In Last Call from Last Call Requested.

The following Last Call Announcement was sent out:

From: The IESG
To: IETF-Announce
CC:
Reply-To: ietf@ietf.org
Subject: Last Call:  (Overview of Pre-Congestion Notification Encoding) to Informational RFC


The IESG has received a request from the Congestion and Pre-Congestion
Notification WG (pcn) to consider the following document:
- 'Overview of Pre-Congestion Notification Encoding'
  as an Informational RFC

The IESG plans to make a decision in the next few weeks, and solicits
final comments on this action. Please send substantive comments to the
ietf@ietf.org mailing lists by 2012-02-23. Exceptionally, comments may be
sent to iesg@ietf.org instead. In either case, please retain the
beginning of the Subject line to allow automated sorting.

Abstract


  The objective of Pre-Congestion Notification (PCN) is to protect the
  quality of service (QoS) of inelastic flows within a Diffserv domain.
  On every link in the PCN domain, the overall rate of the PCN-traffic
  is metered, and PCN-packets are appropriately marked when certain
  configured rates are exceeded.  Egress nodes provide decision points
  with information about the PCN-marks of PCN-packets which allows them
  to take decisions about whether to admit or block a new flow request,
  and to terminate some already admitted flows during serious pre-
  congestion.

  The PCN Working Group explored a number of approaches for encoding
  this pre-congestion information into the IP header.  This document
  provides details of all those approaches along with an explanation of
  the constraints that had to be met by any solution.





The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-pcn-encoding-comparison/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-pcn-encoding-comparison/


No IPR declarations have been submitted directly on this I-D.


2012-02-09
08 David Harrington Ballot writeup text changed
2012-02-09
08 David Harrington Last Call was requested
2012-02-09
08 (System) Ballot writeup text was added
2012-02-09
08 (System) Last call text was added
2012-02-09
08 David Harrington State changed to Last Call Requested from AD Evaluation::AD Followup.
2012-02-09
08 David Harrington Last Call text changed
2012-02-08
08 (System) Sub state has been changed to AD Follow up from New Id Needed
2012-02-08
08 (System) New version available: draft-ietf-pcn-encoding-comparison-08.txt
2012-01-23
08 David Harrington
State changed to AD Evaluation::Revised ID Needed from AD Evaluation.
AD review of pcn-encoding comparison

1) in 2.2.4, "The terminationalgorithm imposed in the standards ..." …
State changed to AD Evaluation::Revised ID Needed from AD Evaluation.
AD review of pcn-encoding comparison

1) in 2.2.4, "The terminationalgorithm imposed in the standards ..." - what standards? references?

2) in 3.3.2.4, why !!! and !? why do we need two ways?

3) in 3.3.3.4, it says this document updates RFC3168, but neither the header nor abstract nor introduction state that this updates RFC3168. see also 4.5.
2012-01-23
08 David Harrington State changed to AD Evaluation from AD Evaluation::External Party.
2012-01-15
07 (System) New version available: draft-ietf-pcn-encoding-comparison-07.txt
2011-11-01
08 Pasi Sarolahti Request for Early review by TSVDIR Completed. Reviewer: Pasi Sarolahti.
2011-10-18
08 David Harrington Request for Early review by TSVDIR is assigned to Pasi Sarolahti
2011-10-18
08 David Harrington Request for Early review by TSVDIR is assigned to Pasi Sarolahti
2011-10-18
08 David Harrington State changed to AD Evaluation::External Party from Publication Requested.
TSVDIR review requested - Pasi Sarolahti
2011-10-10
08 Cindy Morgan
Document shepherd write-up for                                  2011-07-02
draft-ietf-pcn-encoding-comparison-06

  (1.a) Who …
Document shepherd write-up for                                  2011-07-02
draft-ietf-pcn-encoding-comparison-06

  (1.a) Who is the Document Shepherd for this document?

>      Steven Blake, PCN co-chair
 
        Has the
        Document Shepherd personally reviewed this version of the
        document and, in particular, does he or she believe this
        version is ready for forwarding to the IESG for publication?

>      Yes & yes.

  (1.b) Has the document had adequate review both from key WG members
        and from key non-WG members?
       
>      WG members - Yes
       
        Does the Document Shepherd have
        any concerns about the depth or breadth of the reviews that
        have been performed? 

>      No

  (1.c) Does the Document Shepherd have concerns that the document
        needs more review from a particular or broader perspective,
        e.g., security, operational complexity, someone familiar with
        AAA, internationalization or XML?

>      No

  (1.d) Does the Document Shepherd have any specific concerns or
        issues 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.
       
>      No       
       
        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.
       
>      Not applicable
       
        Has an IPR disclosure related to this document
        been filed? If so, please include a reference to the
        disclosure and summarize the WG discussion and conclusion on
        this issue.

>      No

  (1.e) 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? 

>      This document has been under development for several years.
>      The -04 version generated significant discussion on the
>      working group mailing list.  The editor addressed the comments
>      to everyone's satisfaction.  There are no vocal dissenters.

  (1.f) 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
        entered into the ID Tracker.)

>      No

  (1.g) Has the Document Shepherd personally verified that the
        document satisfies all ID nits? (See the Internet-Drafts Checklist
        and http://tools.ietf.org/tools/idnits/). Boilerplate checks are
        not enough; this check needs to be thorough. Has the document
        met all formal review criteria it needs to, such as the MIB
        Doctor, media type and URI type reviews?

>      The document passes ID-nits.


  (1.h) Has the document split its references into normative and
        informative?
       
>      The document is a rationale document and has no normative
>      references.  The reference section is entitled "Informative
>      References".
       
        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
        strategy for their completion? Are there normative references
        that are downward references, as described in [RFC3967]? If
        so, list these downward references to support the Area
        Director in the Last Call procedure for them [RFC3967].

>      Not applicable.

  (1.i) Has the Document Shepherd verified that the document IANA
        consideration section exists and is consistent with the body
        of the document?
       
>      An IANA Considerations section exists, but no requests are
>      made to IANA.
       
        If the document specifies protocol
        extensions, are reservations requested in appropriate IANA
        registries? Are the IANA registries clearly identified? If
        the document creates a new registry, does it define the
        proposed initial contents of the registry and an allocation
        procedure for future registrations? Does it suggest a
        reasonable name for the new registry? See [RFC5226]. If the
        document describes an Expert Review process has Shepherd
        conferred with the Responsible Area Director so that the IESG
        can appoint the needed Expert during the IESG Evaluation?

>      Not applicable

  (1.j) Has the Document Shepherd verified that sections of the
        document that are written in a formal language, such as XML
        code, BNF rules, MIB definitions, etc., validate correctly in
        an automated checker?

>      Not applicable

  (1.k) 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

>    The PCN mechanism in routers in the interior of a PCN domain marks
>    packets when certain configured rates are exceeded.  The PCN working
>    group explored a number of approaches for encoding this pre-congestion
>    information into the IP header.  This document describes the various
>    approaches that were examined and discusses the constraints that had
>    to be satisfied by a viable encoding mechanism.

    Working Group Summary

>      The document was subject to thorough review by the PCN working
>      group, and strong consensus for publication was reached.

    Document Quality

>      The document was reviewed by the document shephard (Steven Blake).
2011-10-10
08 Cindy Morgan Draft added in state Publication Requested
2011-10-10
08 Cindy Morgan [Note]: 'Steven Blake, PCN co-chair (slblake@petri-meat.com) is the document shepherd.' added
2011-07-02
08 Steven Blake Correction: No nits; no -07 version of this document forthcoming.
2011-07-02
08 Steven Blake IETF state changed to Submitted to IESG for Publication from Submitted to IESG for Publication
2011-07-02
08 Steven Blake Document shepherd write-up submitted.  -07 version will be posted to correct one nit (pg. 2 59 lines long).
2011-07-02
08 Steven Blake IETF state changed to Submitted to IESG for Publication from WG Consensus: Waiting for Write-Up
2011-07-02
08 Steven Blake Document shepherd write-up submitted.
2011-07-02
08 Steven Blake
2011-07-02
08 Steven Blake Document shepherd write-up submitted.
2011-07-02
08 Steven Blake Annotation tag Doc Shepherd Follow-up Underway cleared.
2011-07-02
08 Steven Blake Changed protocol writeup
2011-06-17
06 (System) New version available: draft-ietf-pcn-encoding-comparison-06.txt
2011-06-07
08 Steven Blake IETF state changed to WG Consensus: Waiting for Write-Up from WG Document
2011-06-07
08 Steven Blake WGLC succeeded 2011-04-26
2011-06-07
08 Steven Blake Annotation tag Doc Shepherd Follow-Up Underway set.
2011-04-13
05 (System) New version available: draft-ietf-pcn-encoding-comparison-05.txt
2011-02-28
04 (System) New version available: draft-ietf-pcn-encoding-comparison-04.txt
2010-10-22
03 (System) New version available: draft-ietf-pcn-encoding-comparison-03.txt
2010-09-09
08 (System) Document has expired
2010-03-08
02 (System) New version available: draft-ietf-pcn-encoding-comparison-02.txt
2009-10-26
01 (System) New version available: draft-ietf-pcn-encoding-comparison-01.txt
2009-07-06
00 (System) New version available: draft-ietf-pcn-encoding-comparison-00.txt