[AVTCORE] Mirja Kühlewind's Discuss on draft-ietf-avtcore-rtp-circuit-breakers-15: (with DISCUSS and COMMENT)

"Mirja Kuehlewind" <ietf@kuehlewind.net> Tue, 03 May 2016 12:03 UTC

Return-Path: <ietf@kuehlewind.net>
X-Original-To: avt@ietf.org
Delivered-To: avt@ietfa.amsl.com
Received: from ietfa.amsl.com (localhost [IPv6:::1]) by ietfa.amsl.com (Postfix) with ESMTP id 6919812D77A; Tue, 3 May 2016 05:03:21 -0700 (PDT)
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 8bit
From: Mirja Kuehlewind <ietf@kuehlewind.net>
To: The IESG <iesg@ietf.org>
X-Test-IDTracker: no
X-IETF-IDTracker: 6.19.0
Auto-Submitted: auto-generated
Precedence: bulk
Message-ID: <20160503120321.7534.26562.idtracker@ietfa.amsl.com>
Date: Tue, 03 May 2016 05:03:21 -0700
Archived-At: <http://mailarchive.ietf.org/arch/msg/avt/xv54-CrwHNcvumI7U61TTJAtjrE>
Cc: avtcore-chairs@ietf.org, magnus.westerlund@ericsson.com, draft-ietf-avtcore-rtp-circuit-breakers@ietf.org, avt@ietf.org
Subject: [AVTCORE] Mirja Kühlewind's Discuss on draft-ietf-avtcore-rtp-circuit-breakers-15: (with DISCUSS and COMMENT)
X-BeenThere: avt@ietf.org
X-Mailman-Version: 2.1.17
List-Id: Audio/Video Transport Core Maintenance <avt.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/avt>, <mailto:avt-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/avt/>
List-Post: <mailto:avt@ietf.org>
List-Help: <mailto:avt-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/avt>, <mailto:avt-request@ietf.org?subject=subscribe>
X-List-Received-Date: Tue, 03 May 2016 12:03:21 -0000

Mirja Kühlewind has entered the following ballot position for
draft-ietf-avtcore-rtp-circuit-breakers-15: Discuss

When responding, please keep the subject line intact and reply to all
email addresses included in the To and CC lines. (Feel free to cut this
introductory paragraph, however.)

Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html
for more information about IESG DISCUSS and COMMENT positions.

The document, along with other ballot positions, can be found here:


This is about one point in section 7 (ECN) that I think is wrong but I
would like to get some feedback from the authors:
"then ECN-CE marked packets SHOULD
   be treated as if they were lost when calculating if the congestion-
   based RTP circuit breaker"
(also section 5: "The count of ECN-CE marked packets
   contained in those ECN feedback reports is counted towards the number
   of lost packets reported")

We are currently discussion mechanisms where the AQM in the congested
network node sends  much more CE markings than one would see loss (when
using TCP) for the same level of congestion. When treating ECN-CE similar
to loss, such a different behavior could trigger the circuit breaker
unnecessarily. Potentially ECN-CE might not need to be considered here at
all, because as long as there are (only) ECN-CE marks (and no loss) all
data is transmitted correctly to the receiver and therefore there is no
need to trigger a circuit breaker.

Further also in section 7: "ECN-CE marked packets SHOULD be treated as if
they were lost for the
   purposes of congestion control"

This document should not impose any SHOULDs for congestion control as
this doc is only about circuit breaker sand therefore the sentence above
should be removed.


Few more minor comments:

1) reference [I-D.ietf-tsvwg-circuit-breaker] should be normative
2) How is the loss rate in 4.3 calculated if some (but no all) RR are
3) I don't think that most of the text on congestion control in section 2
(as well as the abstract) is necessary for this doc (but it also don't
really hurt)