Pseudowire Congestion Considerations
RFC 7893

[Ballot comment]
-- Abstract --
The abstract seems to have too much detail about what the document
concludes.  The abstract should just be a general statement of what the
document is about -- just enough that someone can determine whether this
document is relevant.

I think I would do something like this:

NEW
  Pseudowires (PWs) have become a common mechanism for tunneling
  traffic, and may be found in unmanaged scenarios competing for
  network resources both with other PWs and with non-PW traffic, such
  as TCP/IP flows.  It is thus worthwhile specifying under what
  conditions such competition is acceptable, where the PW traffic does
  not significantly harm other traffic or contribute more than it
  should to congestion. This document makes that analysis and provides
  recommendations.
END

The rest of the detail needs to be in the document -- perhaps in the
Introduction -- but not in the abstract.

[Ballot comment]
So, very nice. I have one request for you to consider.

In this text:

  The figures presented above demonstrate that TDM service quality
  degradation generally occurs before the TDM PW would consume more
  bandwidth that a comparable TCP flow.  Thus while TDM PWs are unable
  to respond to congestion in a TCP-like manner, TDM PWs that are able
  to deliver acceptable TDM service do not contribute to congestion
  significantly more than a TCP flow.  Combined with our earlier
  conclusion that Ethernet PWs respond in TCP-like fashion, leads to
  our final conclusion that no PW-specific congestion-avoidance
  mechanisms are required.

I can't tell whether or not you're saying that a TPM PW only needs a circuit breaker as an absolute last resort, or it doesn't need a circuit breaker, or something else. If you could finish the last sentence with a word about that, I think it would be helpful.

[Ballot comment]
I have no concerns about the contents of this document, but it bothers me that it doesn’t include all the information.  Yes, I realize the figures can’t be properly included in ASCII art.  I suggest that the authors include a note (at the top of the document or even in the Abstract) that points the reader to the “complete” version.  [Take a look at RFC1305 for an example.]

(Via drafts-lastcall-comment@iana.org): IESG/Authors/WG Chairs:

IANA has reviewed draft-ietf-pals-congcons-01.txt, which is currently in Last Call, and has the following comments:

We understand that this document doesn't require any IANA actions.

While it's often helpful for a document's IANA Considerations section to remain in place upon publication even if there are no actions, if the authors strongly prefer to remove it, IANA does not object.

If this assessment is not accurate, please respond as soon as possible.

The following Last Call announcement was sent out:

From: The IESG
To: "IETF-Announce"
CC: pals-chairs@ietf.org, agmalis@gmail.com, pals@ietf.org, db3546@att.com, draft-ietf-pals-congcons@ietf.org
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (Pseudowire Congestion Considerations) to Informational RFC


The IESG has received a request from the Pseudowire And LDP-enabled
Services WG (pals) to consider the following document:
- 'Pseudowire Congestion Considerations'
  as 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 2015-12-15. 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


  Pseudowires (PWs) have become a common mechanism for tunneling
  traffic, and may be found in unmanaged scenarios competing for
  network resources both with other PWs and with non-PW traffic, such
  as TCP/IP flows.  It is thus worthwhile specifying under what
  conditions such competition is acceptable, i.e., the PW traffic does
  not significantly harm other traffic or contribute more than it
  should to congestion.  We conclude that PWs transporting responsive
  traffic behave as desired without the need for additional mechanisms.
  For inelastic PWs (such as TDM PWs) we derive a bound under which
  such PWs consume no more network capacity than a TCP flow.  For TDM
  PWs, we find that the level of congestion at which the PW can no
  longer deliver acceptable TDM service is never significantly greater
  than this bound, and typically much lower.  Therefore, as long as the
  PW is shut down when it can no longer deliver acceptable TDM service,
  it will never do significantly more harm than even a single TCP flow.
  We propose employing a transport circuit breaker to shut down a TDM
  PW that persistently fails to comply with acceptable TDM service
  criteria.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-pals-congcons/

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-pals-congcons/ballot/


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

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?

Informational. The draft doesn't contain any normative text. Yes.

(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

Pseudowires (PWs) have become a common mechanism for tunneling
traffic, and may be found in unmanaged scenarios competing for network
resources both with other PWs and with non-PW traffic, such as TCP/IP
flows. It is thus worthwhile specifying under what conditions such
competition is acceptable, i.e., the PW traffic does not significantly
harm other traffic or contribute more than it should to congestion. We
conclude that PWs transporting responsive traffic behave as desired
without the need for additional mechanisms. For inelastic PWs (such as
TDM PWs) we derive a bound under which such PWs consume no more
network capacity than a TCP flow. For TDM PWs, we find that the level
of congestion at which the PW can no longer deliver acceptable TDM
service is never significantly greater than this bound, and typically
much lower. Therefore, as long as the PW is shut down when it can no
longer deliver acceptable TDM service, it will never do significantly
more harm than even a single TCP flow. We propose employing a
transport circuit breaker to shut down a TDM PW that persistently
fails to comply with acceptable TDM service criteria.

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?

This draft was the result of one of the chartered work items in the
PWE3 WG, "Publish document outlining PW-specific congestion avoidance
and response guidelines." The process has been slow due to the
challenge of finding a set of authors that were both qualified and
willing to undertake the work in a thorough manner, and once they
volunteered, competing demands for their time and changes in their
employment. The great majority of the work was done during the
lifetime of the PWE3 WG. It received a good set of comments during WG
LC, which have been included in the draft, and it is now ready for
publication.

Note that due to the use of modeling, simulations, and resulting color
graphs, the PDF version of this draft is the canonical version.

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 is informational, so there are no implementations. The draft
received a thorough set of reviews from both WG chairs during WG LC,
and I did another shepherd's review following WG LC comment resolution.

Personnel

  Who is the Document Shepherd? Who is the Responsible Area
  Director?

Andy Malis, Deborah Brungard

(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 did a thorough final review following WG LC comment resolution,
which improved the readability for people perhaps a bit less skilled
in the art than the authors.

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

No.

(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.

N/A

(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.

None.

(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 no IPR associated with the document.

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

No.

(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 draft has full consensus.

(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.

(11) Identify any ID nits the Document Shepherd has found in this
document. (See https://www.ietf.org/tools/idnits/ and the Internet-Drafts
Checklist). Boilerplate checks are not enough; this check needs to be
thorough.

None.

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

N/A

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

All references are Informative. The authors tried to split them into
two sections with an empty Normative section, but the xml2rfc tools
didn't allow this (or so they reported). If an empty Normative
references section is necessary, this can be added by the RFC Editor.

(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?

N/A

(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.

N/A

(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.

N/A

(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).

N/A

(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.

N/A

(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.

N/A