Shepherd writeup

Shepherd Proto Writeup for draft-ietf-dart-dscp-rtp-06

1. Summary

The document shepherd is Ben Campbell. The responsible Area Director is
Richard Barnes.

From the document abstract:

"This document describes the interaction between Differentiated Services
(DiffServ) network quality of service (QoS) functionality and real-time
network communication, including communication based on the Real-time
Transport Protocol (RTP).  DiffServ is based on network nodes applying
different forwarding treatments to packets whose IP headers are marked
with different DiffServ Code Points (DSCPs). WebRTC applications, as
well as some conferencing applications, have begun using the Session
Description Protocol (SDP) bundle negotiation mechanism to send multiple
traffic streams with different QoS requirements using the same network
5-tuple.  Use of different DSCPs to obtain different QoS treatments
within a single network 5-tuple, the results (e.g., reordering) may
cause transport protocol interactions, particularly with congestion
control functionality.  In addition, DSCP markings may be changed or
removed between the traffic source and destination.  This document
covers the implications of these DiffServ aspects for real-time network
communication, including WebRTC."

The document does not attempt to create standards, or state any
normative requirements. Rather, it offers considerations and guidance
for protocol designers and application implementors that consider
sending multiple RTP streams with a shared IP 5-tuple. Therefore the
requested publication type is "informational".

2. Review and Consensus

The DART working group was formed in April of 2014. The working group
was chartered to focus on a constrained problem and conclude quickly.
DART adopted this document with very little controversy.

While the working group is nominally in the RAI area, it has been
effectively a cross-area effort between RAI and TSV. This document
resulted in lively discussion among a core group of experts from both
areas. In general, the discussion converged quickly, and there were no
unresolved controversies.

In the shepherd's opinion, the only impediment to consensus was that
discussion kept overturning rocks, forcing participants to think about
new issues. One notable issue was whether this draft should offer
guidance on the interaction between having multiple DSCPs in a stream
and the multiple stream optimization work
(draft-ietf-avtcore-rtp-multi-stream-optimisation.) The working group
chose to avoid such guidance in this draft, and leave that for the
multi-stream draft to solve.

During the working group last call, we solicited comments from RTCWEB,
AVTCORE, MMUSIC, CLUE, TSVWG, and RMCAT. In the shepherd's opinion, it
has been well reviewed, and represents a strong consensus. The shepherd
does not think it needs any further specific reviews, other than the
usual reviews it would receive during the IETF last call process (for
example, Gen-ART and SecDir).

Since the document does not specify protocol, it will not be directly
implemented. However, we expect that at least the RTCWEB working group
will incorporate guidance from this document into it's output.

3. Intellectual Property

There have been no IPR disclosers related to this document. Both authors
have confirmed that they are not personally aware of any undisclosed

4. Other Points

This document makes no requests of IANA.

The shepherd is not aware of any issues or additional information needed
for the IESG review of this document.