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?

A Proposed Standard RFC is being requested.  The document specifies normative behavior necessary for interoperability of systems using RTP stream duplication.  The title page indicates "Standards Track".

(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

   Packet loss is undesirable for real-time multimedia sessions, but can
   occur due to congestion, or other unplanned network outages.  This is
   especially true for IP multicast networks, where packet loss patterns
   can vary greatly between receivers.  One technique that can be used
   to recover from packet loss without incurring unbounded delay for all
   the receivers is to duplicate the packets and send them in separate
   redundant streams.  This document explains how Real-time Transport
   Protocol (RTP) streams can be duplicated without breaking RTP or RTP
   Control Protocol (RTCP) rules.

Working Group Summary

The document went through a working group last call.  There were comments and the document was updated to resolve all comments.

The work was originally presented in the AVTCORE working group, but following chair and AD discussion was adopted as a work item of the AVTEXT group instead.

Document Quality

The document got good reviews from several AVText members, notably Magnus Westerlund, who brought up several important topics about the document's congestion control, and limitations of its source-association mechanisms, which were resolved during working group last call.

Ali Begen says that Cisco uses duplicated streams "more or less" according to the guidelines in this document, as do several other implementations from the SMPTE community.


The Document Shepherd is Jonathan Lennox.  The Responsible Area Director is Gonzalo Camarillo.

(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 shepherd read the submitted version of the document fully, as well as reviewing several earlier versions of the document.

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

This document was reviewed by multiple people from AVText and all comments
were addressed.

(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 broader reviews are needed.

(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.

(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.

Both authors have confirmed this.  Ali Begen has referred to disclosure 1656 (see below); Colin Perkins confirmed that he had no IPR disclosures that needed to be made. 

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

One IPR disclosure has been filed, <>, by Cisco, on an earlier version of the individual submission that was adopted as the working group draft.  Ali Begen has confirmed that the same disclosure applies to the working group document.  This disclosure did not occasion any comment in the working group.

(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?   

While only a relatively small number of people have commented on the draft, this is not atypical for the AVTEXT working group, and most of the group's most active (and expert) participants have indicated agreement with the document.

(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

Two of the document's normative references reference previous versions of Internet-Drafts that were revised following IESG review, but the changes that were made do not affect the contents of this draft.

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

Not applicable.

(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).

The document has no requirements of 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.

The document has no requirements of IANA.

(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.

The document contains no sections written in a formal language.