Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-ietf-avtcore-rtp-circuit-breakers-15: (with DISCUSS and COMMENT)
Colin Perkins <csp@csperkins.org> Tue, 10 May 2016 15:34 UTC
Return-Path: <csp@csperkins.org>
X-Original-To: avt@ietfa.amsl.com
Delivered-To: avt@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 8D3FD12D728; Tue, 10 May 2016 08:34:11 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -4.2
X-Spam-Level:
X-Spam-Status: No, score=-4.2 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3] autolearn=ham autolearn_force=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id gvx1F8Xsi9BI; Tue, 10 May 2016 08:34:09 -0700 (PDT)
Received: from balrog.mythic-beasts.com (balrog.mythic-beasts.com [IPv6:2a00:1098:0:82:1000:0:2:1]) (using TLSv1.2 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id DB16012D72D; Tue, 10 May 2016 08:34:08 -0700 (PDT)
Received: from [130.209.247.112] (port=59220 helo=mangole.dcs.gla.ac.uk) by balrog.mythic-beasts.com with esmtpsa (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.80) (envelope-from <csp@csperkins.org>) id 1b09fg-0001AG-Ei; Tue, 10 May 2016 16:34:06 +0100
Content-Type: text/plain; charset="utf-8"
Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\))
From: Colin Perkins <csp@csperkins.org>
In-Reply-To: <249B6CE6-805D-4B65-80DE-A8B5280A059B@kuehlewind.net>
Date: Tue, 10 May 2016 16:34:03 +0100
Content-Transfer-Encoding: quoted-printable
Message-Id: <4FEBFDED-ADEE-40E5-954E-DA6FB072AAAA@csperkins.org>
References: <20160503120321.7534.26562.idtracker@ietfa.amsl.com> <32C2F93E-9CB9-4645-9C42-320AA8B24ED5@csperkins.org> <2EC09917-2E05-407D-AA7F-38C73B179C4B@kuehlewind.net> <CACHXSv6vggo7KN1HOqQyjbzro6Eq0zGNcfJ9poKnfpBipBn7Vw@mail.gmail.com> <249B6CE6-805D-4B65-80DE-A8B5280A059B@kuehlewind.net>
To: "Mirja Kuehlewind (IETF)" <ietf@kuehlewind.net>
X-Mailer: Apple Mail (2.3124)
X-BlackCat-Spam-Score: -28
X-Mythic-Debug: Threshold = On =
Archived-At: <http://mailarchive.ietf.org/arch/msg/avt/tvQrPVEHAy7Oo4RLjjCkSALAZ5k>
Cc: avtcore-chairs@ietf.org, Magnus Westerlund <magnus.westerlund@ericsson.com>, draft-ietf-avtcore-rtp-circuit-breakers@ietf.org, avt@ietf.org, The IESG <iesg@ietf.org>, Varun Singh <varun@callstats.io>
Subject: Re: [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
Precedence: list
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, 10 May 2016 15:34:11 -0000
Hi Mirja, Persistant ECN-CE marks indicates a flow is causing persistent congestion, no? Colin > On 10 May 2016, at 16:18, Mirja Kuehlewind (IETF) <ietf@kuehlewind.net> wrote: > > Hi Varun, > > I would say that parts of tsvg-circuit-breaker are so general that they also apply for this doc. > > However, in any case my point it that (while congestion control may or may not threat ECN-CE marks similar as loss), circuit breaker MUST NOT do that because only ECN-CE marks without loss clearly shows that everything is working right and there is not need for a circuit breaker to react. That is really important to get right! > > Mirja > > >> Am 05.05.2016 um 16:43 schrieb Varun Singh <varun@callstats.io>: >> >> Hi Mirja, >> >> see inline. >> >> Regards, >> Varun >> >> On Wed, May 4, 2016 at 1:52 PM, Mirja Kuehlewind (IETF) >> <ietf@kuehlewind.net> wrote: >>> >>>> Not sure I agree. The circuit breaker needs to treat lost and CE-marked packets the same as a congestion control algorithm, and the ECN specifications say that the response to CE marks needs to be the same as the response to loss. >>> >>> I disagree, given the explanation above that ECN-CE marking indicate that all traffic have been transmitted correctly. It’s only an input for a control mechanism/loop and should not be used as input for a circuit breaker, at least not the same way as loss it used. >>> >>> You could calculate the loss and ecn ratio separately and e.g. lower the k value if there is also a high level of CE marks. However, only CE marks without loss should not trigger a circuit breaker. This is also what ietf-tsvwg-circuit-breaker says: >>> "If Explicit >>> Congestion Notification (ECN) is enabled [RFC3168], an egress >>> meter MAY also count the number of ECN congestion marks/event per >>> measurement interval, but even if ECN is used, loss MUST still be >>> measured, since this better reflects the impact of persistent >>> congestion.“ >>> >> >> First, I believe the draft assumes ECN-CE should be considered as lost >> packets in addition to the lost packets. >> >> Second, I am not sure the text from the tsvg-circuit-breaker applies >> in this case. Because the calculation in section 4.3 takes place at >> the sender. And the sender receives the ECN-CE counter from >> the receiver in an RTCP XR report (RFC6679). >> >> In RFC6679: the receiver reports the cumulative lost packets and >> cumulative ECN counters. So at the sender, there may not be >> sufficient information to say if the ECN-CE packets were >> accompanied by loss or not. >> >> >>>> >>>>> ---------------------------------------------------------------------- >>>>> COMMENT: >>>>> ---------------------------------------------------------------------- >>>>> >>>>> Few more minor comments: >>>>> >>>>> 1) reference [I-D.ietf-tsvwg-circuit-breaker] should be normative >>>> >>>> This was discussed in relation to Ben’s AD review. I think you can implement the RTP circuit breaker without reading the TSV draft, so informative seems correct. However, I don’t much care either way. >>> >>> I will double-check this; was not aware of any previous discussions here. I still think it should be normative... >>> >>>> >>>>> 2) How is the loss rate in 4.3 calculated if some (but no all) RR are >>>>> lost? >>>> >>>> There’s no obvious way for the receiver of the RRs to know that some were lost, so the calculation will proceed as if the reporting interval was longer. >>> >>> Hm… what’s about using the (difference of )total number of losses instead? >>> >> >> As Colin indicated there is no way to know that the report was lost. >> >> In (RFC3550), the fraction lost is defined to be the number of packets >> lost divided by the number of packets expected since the last report. >> And the formula in Section 4.3 does not rely on all receiving all >> reports. Furthermore, the RTT and fraction lost plugged into the >> formula are based on the same report. >> >> Is the concern that the fraction lost may not be sufficiently >> indicative if the preceding RTCP RR was lost? >> >> >> >> -- >> Founder, CEO, callstats.io >> http://www.callstats.io >> Analytics and Optimizations for WebRTC. >> >> We are hiring: www.callstats.io/jobs/ >> > -- Colin Perkins https://csperkins.org/
- [AVTCORE] Mirja Kühlewind's Discuss on draft-ietf… Mirja Kuehlewind
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Mirja Kuehlewind (IETF)
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Colin Perkins
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Mirja Kuehlewind (IETF)
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Varun Singh
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Mirja Kuehlewind (IETF)
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Colin Perkins
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Colin Perkins
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Varun Singh
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Colin Perkins
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Mirja Kuehlewind (IETF)
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Mirja Kuehlewind (IETF)
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Colin Perkins
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Mirja Kuehlewind (IETF)
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Colin Perkins
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Mirja Kuehlewind (IETF)
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Colin Perkins
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Colin Perkins
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Mirja Kuehlewind (IETF)
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Mirja Kuehlewind (IETF)
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Colin Perkins
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Mirja Kuehlewind (IETF)
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Colin Perkins
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Mirja Kuehlewind (IETF)
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Magnus Westerlund
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Mirja Kuehlewind (IETF)
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Magnus Westerlund
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Mirja Kuehlewind (IETF)
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Magnus Westerlund
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Mirja Kuehlewind (IETF)
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Colin Perkins
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Ben Campbell
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Alissa Cooper
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Ben Campbell
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Colin Perkins
- Re: [AVTCORE] Mirja Kühlewind's Discuss on draft-… Mirja Kuehlewind (IETF)