Additional Policies for the Partially Reliable Stream Control Transmission Protocol Extension
draft-ietf-tsvwg-sctp-prpolicies-07

[Ballot comment]
1.
  Using the Priority Policy allows the sender of a user message to
  specify a priority.  When storing a user message in the send buffer
  while there is not enough available space, the SCTP stack at the
  sender side MAY abandon other user messages of the same SCTP
  association with a priority lower than the provided one.

From the same SCTP association or the same stream within the SCTP association? Or is this implementation specific?

2.
While reading through the draft, I was actually wondering how I could use those extensions in IPFIX.
The first one is not applicable. Then I found in section 3.2:

  The Priority Policy can be used in the IPFIX protocol stack.  See
  [RFC7011] for more information.

This is a little lit light. I believe you should explain the use case you have in mind... because I don't believe this was an IPFIX requirement.

[Ballot comment]


So I assume the ability to say "please re-tx this 2^32-1
times" is said to not introduce any new security
consideration, because that is not sent over the wire.
However, could there not be a DoS against a kernel from
userland? And if that limit is set based on some WebRTC JS
(is it? I don't know) then wouldn't that be a way to DoS a
browser and possibly the other end of a WebRTC data channel
too?

So, perhaps noting the above would be good, as well as
saying that implementations SHOULD or MUST have a limit that
they enforce on the max number of re-tx's? (Apologies if
that is there already and I missed it.)

[Ballot comment]
-- Section 3.1 --

  The Limited Retransmissions Policy can be used with data channels in
  the WebRTC protocol stack.  See [I-D.ietf-rtcweb-data-channel] for
  more information.

I wonder whether implementors might misunderstand, and think this is meant to be restrictive.  Please consider changing the wording (here and in 3.2) to something like this:

NEW
  The Limited Retransmissions Policy was designed to be used with
  data channels in the WebRTC protocol stack (see
  [I-D.ietf-rtcweb-data-channel]), and can also be used in other
  appropriate situations.
END

...or maybe...

NEW
  The WebRTC protocol stack (see [I-D.ietf-rtcweb-data-channel]), is
  an example of where the Limited Retransmissions Policy might be
  used.
END

-- Section 3.2 --

  When storing a user message in the send buffer
  while there is not enough available space, the SCTP stack at the
  sender side MAY abandon other user messages of the same SCTP
  association with a priority lower than the provided one.  The
  algorithm for selecting the message being abandoned is implementation
  specific.

A minor point: the first part is written as allowing multiple messages to be abandoned, and the last sentence is written in the singular.  Should the second part say "message(s)" ?

-- Section 4.2 --

The table shows the two policies that come out of RFC 6458 and the two that come from this document.  Is it worth it to create a (FCFS?) registry for these names, to document them and provide references?

[Ballot discuss]
I have four things I'd like to discuss; three are up here, and one is down in the non-blocking comments.

1. Section 4 says this:

  Please note that this section is informational only.

How are sections 4.2 thru 4.5 not normative?

2. The table in Section 4.2 shows the two policies that come out of RFC 6458 and the two that come from this document.  Is this the time to create a registry for these?

3. In Section 6, you say that this adds no security considerations.  Are there really no security considerations introduced by new conditions under which messages can be abandoned?  And who determines the message priorities?  Are there no security considerations involved in that determination?  Is there no discussion at all that might be useful in determining reasonable values for Limited Retransmission Policy?

[Ballot comment]
-- Section 3.1 --

  The Limited Retransmissions Policy can be used with data channels in
  the WebRTC protocol stack.  See [I-D.ietf-rtcweb-data-channel] for
  more information.

This isn't a DISCUSS, because I don't think I want to block the document on this, but I would like to discuss it:  Is this meant to put restrictions on where the Limited Retransmissions Policy can be used?  If so, it should be clearer about that.  If not, what's the reason for this specific shout-out?

The same question applies to this paragraph from Section 3.2:

  The Priority Policy can be used in the IPFIX protocol stack.  See
  [RFC7011] for more information.


-- Section 3.2 --

  When storing a user message in the send buffer
  while there is not enough available space, the SCTP stack at the
  sender side MAY abandon other user messages of the same SCTP
  association with a priority lower than the provided one.  The
  algorithm for selecting the message being abandoned is implementation
  specific.

A minor point: the first part is written as allowing multiple messages to be abandoned, and the last sentence is written in the singular.  Should the second part say "message(s)" ?

IESG/Authors/WG Chairs:

IANA has reviewed draft-ietf-tsvwg-sctp-prpolicies-05, which is currently in Last Call, and has the following comments:

We understand that, upon approval of this document, there are no IANA Actions that need completion.

While it is helpful for the IANA Considerations section of the document to remain in place upon publication, if the authors prefer to remove it, IANA doesn't 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:
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (Additional Policies for the Partial Reliability Extension of the Stream Control Transmission Protocol) to Proposed Standard


The IESG has received a request from the Transport Area Working Group WG
(tsvwg) to consider the following document:
- 'Additional Policies for the Partial Reliability Extension of the
  Stream Control Transmission Protocol'
  as Proposed Standard

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 2014-12-1. 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


  This document defines two additional policies for the Partial
  Reliability Extension of the Stream Control Transmission Protocol
  (PR-SCTP) allowing to limit the number of retransmissions or to
  prioritize user messages for more efficient send buffer usage.




The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-tsvwg-sctp-prpolicies/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-tsvwg-sctp-prpolicies/ballot/


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

A revised I-D may not be needed - I sent questions to the shepherd that may result in a revised I-D, but this is the Substate that seemed to reflect that most clearly ...

(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?
PS


(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:
The Stream Control Transmission Protocol (SCTP) is a transport protocol
originally defined to run on top of the network protocols IPv4 or IPv6.
This document defines two additional policies for the Partial
Reliability Extension of the Stream Control Transmission Protocol
(PR-SCTP) allowing to limit the number of retransmissions or to
prioritize user messages for more efficient send buffer usage.


Document Quality:
The document is thought ready for publication. Note the socket API
information is traditionally included as an informational section within
SCTP specs. This API is thought to be completely implemented in FreeBSD,
to be released in FreeBSD 10.1


Personnel:
Who is the Document Shepherd?
G Fairhurst (TSVWG Co-Chair)


Who is the Responsible Area Director?
Spencer Dawkins (TSV 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 was reviewed against related documents and is thought ready
to proceed.


(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.
No


(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


(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


(8) Has an IPR disclosure been filed that references this document? If
so, summarize any WG discussion and conclusion regarding the IPR
disclosures.
None are known


(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?
A WGLC was made in TSVWG, to end July 21st, 2014, with 5 comments. All
were supportive of publishing a spec. on this topic. The update to the
revised ID was discussed in TSVWG after the WGLC.
(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 http://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.
None


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


(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?
OK


(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.
No


(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


(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).
This document requires no actions from IANA


(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.
None


(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.
None--
Prof Gorry Fairhurst, School of Engineering, University of Aberdeen.
The University of Aberdeen is a charity registered in Scotland,
No SC013683.