Re: [bmwg] Martin Duke's Discuss on draft-ietf-bmwg-b2b-frame-03: (with DISCUSS and COMMENT)
Martin Duke <martin.h.duke@gmail.com> Wed, 16 December 2020 18:53 UTC
Return-Path: <martin.h.duke@gmail.com>
X-Original-To: bmwg@ietfa.amsl.com
Delivered-To: bmwg@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id DE2043A0B10; Wed, 16 Dec 2020 10:53:01 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.097
X-Spam-Level:
X-Spam-Status: No, score=-2.097 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, HTML_MESSAGE=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=gmail.com
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 pSw-T5QRy0_n; Wed, 16 Dec 2020 10:52:57 -0800 (PST)
Received: from mail-il1-x136.google.com (mail-il1-x136.google.com [IPv6:2607:f8b0:4864:20::136]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 2B9F53A0B08; Wed, 16 Dec 2020 10:52:57 -0800 (PST)
Received: by mail-il1-x136.google.com with SMTP id n9so12560928ili.0; Wed, 16 Dec 2020 10:52:57 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=YI8wbKt8K1/CCv/Sey15bB6+RrksSa7GD6CuIN7xlsg=; b=chmSatba/oAwrqFUofIzhU/+OSCLOo2KL5ZXdK2KRgmUMrkg+LCZk7Gh1UEzaM1Ib9 Il/nqcdWYiv9EJaCDRBCEa8xjd5QAai8ZYlaM5JPXO0z72FxnE/3i7PswoEAu414haux DDQiBU0KT6aBuzOsyerIMovYujFL5ujKkDOtgtD1cYssJsh0Yww9fB3/n+uymymiLn3n 2ES1zakooJoA1iRp9krEwagJwxoSmlbTC/ZMfu1Q00ECCz3hNXD0t/Nwl0wQhG2SBWMb LWTwCYRBpLJHfWnLMHquL5t1Pr40kARjg2yMXrlSOlnfNr8L5whuGYFmf9jaYS8RJPXe idgg==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=YI8wbKt8K1/CCv/Sey15bB6+RrksSa7GD6CuIN7xlsg=; b=lfbHyNAjngFQFw6JnnqDBQn4fm9ro2qUUXV1UjDLvxgGmQFnLzkmG4X/VpZBjUdglJ p0ymQ0s6vn0sgBoygjRMz+y5ijN5SZ6aeQ9Xy7qxRLIL26VoZmoUcfpQJyAOmkf+IBuQ kmgrZWzFlFQNo6SPYnBEimM2VRURfuHfgSTbH9/l1Y0ByUCMRqhraQTyogVYtWUpZON7 9XLQQuDJL/6QM3obnfHrN4i/rXKhMcsD+flGb3biavlGxd1VRWyVfd4ozIGGe+O7RqM4 RLQFb2Rht0BZNanUeH85kiMfWBAF6+nissQCBnhgxtKhm3HFLvD9PR+mYlLfpXoI4O80 YN7Q==
X-Gm-Message-State: AOAM533SobUYMQtH6gVDzFfWB1Qolah8O+Q0tLW4IuDqfhuCHEXW0SCZ TueVbjxBZBD0u+eNNbs4d1QfX/lcj2BfWxZ0jqbrUYV45as=
X-Google-Smtp-Source: ABdhPJzqzkgGxbBFmwbBaNcbPCPyFeLnBPk5GtzriZmPuKsghL1e+mRDQxXDQ0ANz5cfrI/thYiAanBcRUZCsP9pxCw=
X-Received: by 2002:a92:d44f:: with SMTP id r15mr47977640ilm.237.1608144776350; Wed, 16 Dec 2020 10:52:56 -0800 (PST)
MIME-Version: 1.0
References: <160755503926.27888.3173906725876085467@ietfa.amsl.com> <4D7F4AD313D3FC43A053B309F97543CF014766D179@njmtexg5.research.att.com> <BC09F3BD-B046-44D8-8063-3EA10E9DE574@sobco.com> <4D7F4AD313D3FC43A053B309F97543CF014766EB8C@njmtexg5.research.att.com> <A720588B-2F9C-4EC8-8269-E27D0B3A2973@sobco.com> <4D7F4AD313D3FC43A053B309F97543CF014766F1FE@njmtexg5.research.att.com> <27AFD4CF-D66F-451D-AE2C-4D6CED32943E@sobco.com> <4D7F4AD313D3FC43A053B309F97543CF014766FDE3@njmtexg5.research.att.com>
In-Reply-To: <4D7F4AD313D3FC43A053B309F97543CF014766FDE3@njmtexg5.research.att.com>
From: Martin Duke <martin.h.duke@gmail.com>
Date: Wed, 16 Dec 2020 10:52:45 -0800
Message-ID: <CAM4esxTY7OgZDmq25=86A66y1+D_cG0FEMP08zFg2shrxZza0Q@mail.gmail.com>
To: "MORTON, ALFRED C (AL)" <acm@research.att.com>
Cc: "Scott O. Bradner" <sob@sobco.com>, The IESG <iesg@ietf.org>, "draft-ietf-bmwg-b2b-frame@ietf.org" <draft-ietf-bmwg-b2b-frame@ietf.org>, "bmwg-chairs@ietf.org" <bmwg-chairs@ietf.org>, "bmwg@ietf.org" <bmwg@ietf.org>
Content-Type: multipart/alternative; boundary="0000000000002450d905b6996241"
Archived-At: <https://mailarchive.ietf.org/arch/msg/bmwg/iqfzLHOIXSiaiTFgYRUiCocwtSg>
Subject: Re: [bmwg] Martin Duke's Discuss on draft-ietf-bmwg-b2b-frame-03: (with DISCUSS and COMMENT)
X-BeenThere: bmwg@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Benchmarking Methodology Working Group <bmwg.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/bmwg>, <mailto:bmwg-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/bmwg/>
List-Post: <mailto:bmwg@ietf.org>
List-Help: <mailto:bmwg-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/bmwg>, <mailto:bmwg-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 16 Dec 2020 18:53:02 -0000
Looks good to me. On Wed, Dec 16, 2020 at 10:32 AM MORTON, ALFRED C (AL) <acm@research.att.com> wrote: > Hi Scott, > > I appreciate your practical insights shared below, as always! > > Let me propose some text, expressing both the concerns you and Martin > raised, and the caution that's in my mind (buffer-bloat sizes change the > time scale of testing, but the problem we currently face with the "latest > technology" is a very small buffer <<1 sec and difficulty increasing the > size through configuration changes = we need to re-run tests often to > determine implementation success/failure). > > The duration of the trial includes three REQUIRED components: > ... > 3. At least 2 seconds not overlapping the time to receive the burst (2.), > to ensure that DUT buffers have depleted. Longer times MUST be used when > conditions warrant, such as when buffer times >2 seconds are measured or > when burst sending times are >2 seconds, but care is needed since this time > component directly increases trial duration and many trials and tests > comprise a complete benchmarking study. > > hope this works, > Al > > > > -----Original Message----- > > From: Scott O. Bradner [mailto:sob@sobco.com] > > Sent: Wednesday, December 16, 2020 6:44 AM > > To: MORTON, ALFRED C (AL) <acm@research.att.com> > > Cc: Martin Duke <martin.h.duke@gmail.com>; The IESG <iesg@ietf.org>; > > draft-ietf-bmwg-b2b-frame@ietf.org; bmwg-chairs@ietf.org; bmwg@ietf.org > > Subject: Re: [bmwg] Martin Duke's Discuss on > draft-ietf-bmwg-b2b-frame-03: > > (with DISCUSS and COMMENT) > > > > > > > > > On Dec 15, 2020, at 5:04 PM, MORTON, ALFRED C (AL) > > <acm@research.att.com> wrote: > > > > > > Hi Scott, > > > > > > Please see my replies below, marked [acm], with a couple of questions. > > > I hope I'm not missing something obvious, so trying to be very clear in > > all replies! > > > But I could be overlooking something, and if so I will learn something > > very soon... > > > > > >> -----Original Message----- > > >> From: Scott O. Bradner [mailto:sob@sobco.com] > > >> Sent: Tuesday, December 15, 2020 9:06 AM > > >> To: MORTON, ALFRED C (AL) <acm@research.att.com> > > >> Cc: Martin Duke <martin.h.duke@gmail.com>; The IESG <iesg@ietf.org>; > > >> draft-ietf-bmwg-b2b-frame@ietf.org; bmwg-chairs@ietf.org; > bmwg@ietf.org > > >> Subject: Re: [bmwg] Martin Duke's Discuss on > draft-ietf-bmwg-b2b-frame- > > 03: > > >> (with DISCUSS and COMMENT) > > >> > > >> I basically understood that but it seemed to me that using a fixed (2 > > >> second) extra time, which is unrelated > > >> to whatever time that the burst might have taken to be sent seemed > > risky > > >> since I could > > >> imagine cases where the play out speed was less than the receive speed > > > > > > [acm] > > > I guess I don't understand your example, where (buffer?) play-out speed > > plays a role in the results, and how play-out speed could be less than > the > > receive speed in the multi-second time scale of the buffer-bloat example. > > I think (buffer) play-out speed and receive speed should be nominally the > > same. > > > > > > I expect that generally they would be about the same but its all software > > and different routines would > > handle input & output so one can not be sure - in addition the system > > could be adding keep-alive packets, > > routing updates etc to the output stream (not that they would take much > > time to send) > > > > > > Although RFC 2544 Throughput definition is based on offered load > > delivered loss-free to the receiver, we use it here as the best > > approximation available for packet header processing rate (equal to > > playout rate from the buffer?), egress from the DUT, and the speed at > > which the test system receives packets. > > > > > > So, in our diagram from the memo: > > > > > > |------------ DUT --------| > > > Generator -> Ingress -> Buffer -> HeaderProc -> Egress -> Receiver > > > > > > Is your play-out speed the HeaderProc speed, or Egress speed? > > > > > > And how can the (buffer) play-out speed be less than the speed at a > > subsequent interface (for very long)? > > > > "very long" is a relative term :-) > > > > I agree that there should not be any issue if 2 seconds is long relative > > to the burst length but > > maybe not so if the burst length is long relative to 2 seconds (e.f. it > > takes a minute or two > > to fill the buffer) > > > > Scott > > > > > > help me understand the mechanics I'm overlooking, my friend! > > > > > >> > > >> but if you are convinced that the 2 seconds extra time would cover all > > >> possible cases then go to it > > > [acm] > > > > > > Well, we say "at least 2 seconds" and allow for customization if > > necessary. > > > > > > As you know, I've conducted LOTS of production network testing, where > we > > have used static waiting times to distinguish packet loss from long > delay, > > and prescribed the same in IPPM RFCs, etc. A static waiting time "Tmax" > > has served us well. > > > > > > Here, we have the added stability of the Isolated Test Environment > (ITE, > > as Kevin Dubray called it), and the three time-component definition of > > trial duration, where we wait 2 seconds after the last packet on seen > > egress (it is more like a cool-down interval between trials). I think all > > the adaptation we need comes from explicit recognition that the time for > > the Test Receiver to receive the entire burst depends on the buffer size, > > the DUT header processing rate, the actual interface speed, etc. IOW, all > > the unknown variables. > > > > > > Thanks again for your time, Scott! > > > Al > > > > > >> > > >> Scott > > >> > > >> > > >>> On Dec 14, 2020, at 7:24 PM, MORTON, ALFRED C (AL) > > >> <acm@research.att.com> wrote: > > >>> > > >>> Hi Scott, thanks for helping with this discussion. > > >>> > > >>> I'm trying to formulate adaptive extra time based on the time it > takes > > >> to *receive* the burst, with the additional "at least 2 seconds" > > waiting > > >> time to be sure we received all the packets that might arrive. Let me > > try > > >> drawing the timeline that's in my mind, and I'll use a buffer-bloat > > case > > >> example of a 1 second buffer (which dominates all other buffers in the > > >> DUT). > > >>> > > >>> One of the key contributions of this memo is recognizing that the > > buffer > > >> is being emptied while the burst of back-to-back frames is > > simultaneously > > >> trying to fill the buffer. > > >>> > > >>> Assume that the RFC 2544 Throughput is only half of the back-to-back > > >> frame rate for the frame size used. > > >>> > > >>> From the draft: > > >>> 4. A helpful concept is the buffer filling rate, which is the > > >>> difference between the Max Theoretical Frame Rate (ingress) and > > >>> the Measured Throughput (HeaderProc on egress). If the actual > > >>> buffer size in frames was known, the time to fill the buffer > > >>> during a measurement can be calculated using the filling rate as > > >>> a check on measurements. However, the Buffer in the model > > >>> represents many buffers of different sizes in the DUT data path. > > >>> > > >>> So (danger: calculating while typing and drawing!), a 1 second burst > > of > > >> B2B frames only raises the occupation buffer to 50%, and another > second > > of > > >> transmission is needed before reaching 100% occupation. > > >>> > > >>> Trial > > >>> Time, sec: 0 1 2 3 4 5 > > >> 6 > > >>> > > >>> Sender: |==========|==========| > > >>> Receiver: |= = = = = |= = = = = |= = = = = |= = = = =| > > >>> Waiting Time | | > > >> | > > >>> > > >> Trial > > >>> > > >> Ends > > >>> > > >>> In the ideal example timeline above, the back-to-back burst stopped > > >> exactly when the buffer reached capacity, so there is no loss. The > > buffer > > >> fill rate is half the back-to-back rate. Also, it takes 2 seconds to > > >> deplete the buffer and for frames to stop arriving at the receiver. > > Only > > >> then do we start the 2 second waiting time to ensure no more frames > > will > > >> arrive! > > >>> > > >>> While we're here, let's look at a calculation from the memo: > > >>> > > >>> Corrected DUT Buffer Time = > > >>> / \ > > >>> Implied DUT |Implied DUT Measured Throughput | > > >>> = Buffer Time - |Buffer Time * -------------------------- | > > >>> | Max Theoretical Frame Rate | > > >>> \ / > > >>> = 2 - [ 2 * 0.5 ] seconds > > >>> = 1 second > > >>> > > >>> and we avoid the error of calculating buffer time based on the > > sender's > > >> burst duration alone. > > >>> > > >>> hope this helps, > > >>> Al > > >>> > > >>> > > >>>> -----Original Message----- > > >>>> From: Scott O. Bradner [mailto:sob@sobco.com] > > >>>> Sent: Saturday, December 12, 2020 5:18 PM > > >>>> To: MORTON, ALFRED C (AL) <acm@research.att.com> > > >>>> Cc: Martin Duke <martin.h.duke@gmail.com>; The IESG <iesg@ietf.org > >; > > >>>> draft-ietf-bmwg-b2b-frame@ietf.org; bmwg-chairs@ietf.org; > > bmwg@ietf.org > > >>>> Subject: Re: [bmwg] Martin Duke's Discuss on draft-ietf-bmwg-b2b- > > frame- > > >> 03: > > >>>> (with DISCUSS and COMMENT) > > >>>> > > >>>> this would seem to work if 2 seconds is significantly longer than it > > >> takes > > >>>> to send the burst - but if it takes 2 second to send the burst > > >>>> then 2 seconds extra buffer could easily lose packets - seems to me > > >> that > > >>>> he extra time should be related to the time it takes to send the > > burst > > >>>> > > >>>> e.g 50% of the burst time but not less than 2 seconds > > >>>> > > >>>> Scott > > >>>> > > >>>> > > >>>>> On Dec 12, 2020, at 10:18 AM, MORTON, ALFRED C (AL) > > >>>> <acm@research.att.com> wrote: > > >>>>> > > >>>>> Hi Martin, thanks for your review and comment, > > >>>>> please see my reply, [acm] below, > > >>>>> Al > > >>>>> > > >>>>>> -----Original Message----- > > >>>>> ... > > >>>>>> > > >>>>>> > ------------------------------------------------------------------- > > -- > > >> - > > >>>>>> DISCUSS: > > >>>>>> > ------------------------------------------------------------------- > > -- > > >> - > > >>>>>> > > >>>>>> Thank you for engaging with the TSVART review. Despite the > > >> wordsmithing > > >>>> that > > >>>>>> has gone on, I am not sure that we have captured the correct text. > > >>>>>> > > >>>>>> The proposed change is: > > >>>>>>> I clarified: > > >>>>>>> The duration of the trial MUST include at least 2 seconds in > > >> addition > > >>>> to the time > > >>>>>>> required to send and receive each burst of frames, to ensure that > > >> DUT > > >>>> buffers to deplete. > > >>>>>>> and I'll add: > > >>>>>>> The upper search limit for the time to send each burst MUST be > > >>>> configurable as > > >>>>>>> high as 30 seconds (buffer time results > > >>>>>>> reported at the configured upper limit are likely invalid, and > the > > >>>> test MUST > > >>>>>>> be repeated with a higher search limit). > > >>>>>> > > >>>>>> But IIUC it's the additional time that needs to scale up. > > >>>>> [acm] > > >>>>> > > >>>>> In the revised text where David and I reached agreement, we > > identified > > >> 3 > > >>>> time components of the trial duration, making the duration variable: > > no > > >>>> longer static and at "at least 2 seconds". > > >>>>> > > >>>>> 1. the time to send the burst of frames (at the back-to-back rate), > > >>>> determined by the search algorithm > > >>>>> 2. the time to receive the transferred burst of frames (at the > > RFC2544 > > >>>> Throughput rate), possibly truncated by buffer overflow, but > > certainly > > >>>> including the latency of the DUT with or without buffer-bloat > > >>>>> 3. at least 2 seconds in addition to the time to receive the burst > > >> (2.), > > >>>> to ensure that DUT buffers have depleted. > > >>>>> > > >>>>> So, both components 1. and 2. are variables, and the burst receive > > >> time > > >>>> component (2.) compensates for large buffers, non-back-to-back burst > > >>>> egress, and anything else that contributes to DUT latency. The final > > >> "at > > >>>> least 2 seconds" is simply about making sure the trial is really > over > > >>>> before moving on in an automated test - we won't make an error if > > >> frames > > >>>> trickle-out very late for some unfortunate reason. > > >>>>> > > >>>>>> A layman's reading of > > >>>>>> the document, IMO, suggests that the burst length has a binary > > search > > >>>> but the 2 > > >>>>>> seconds of waiting can be fixed. > > >>>>> [acm] > > >>>>> Yes, that's right, plus all the other factors above. > > >>>>> > > >>>>> So, let's try this, but I'm trying not to extend or complicate the > > >>>> buffer time << 2 seconds testing for the sake of the buffer-bloat > > case: > > >>>>> > > >>>>> -=-=-=-=-=-=- > > >>>>> > > >>>>> The duration of the trial includes three REQUIRED components: > > >>>>> > > >>>>> 1. the time to send the burst of frames (at the back-to-back rate), > > >>>> determined by the search algorithm > > >>>>> 2. the time to receive the transferred burst of frames (at the > > RFC2544 > > >>>> Throughput rate), possibly truncated by buffer overflow, and > > certainly > > >>>> including the latency of the DUT > > >>>>> 3. at least 2 seconds not overlapping the time to receive the burst > > >>>> (2.), to ensure that DUT buffers have depleted. > > >>>>> > > >>>>> The upper search limit for the time to send each burst MUST be > > >>>> configurable as high as 30 seconds (buffer time results reported at > > or > > >>>> near the configured upper limit are likely invalid, and the test > MUST > > >> be > > >>>> repeated with a higher search limit). > > >>>>> > > >>>>> -=-=-=-=-=-=-=-=- > > >>>>> > > >>>>> Does that wording do it? > > >>>>> > > >>>>>> > > >>>>>> > ------------------------------------------------------------------- > > -- > > >> - > > >>>>>> COMMENT: > > >>>>>> > ------------------------------------------------------------------- > > -- > > >> - > > >>>>>> > > >>>>>> Other than that, this a well-written document. Thanks! > > >>>>> [acm] > > >>>>> Thank you! > > >>>>> > > >>>>>> > > >>>>>> > > >>>>> > > >>>>> _______________________________________________ > > >>>>> bmwg mailing list > > >>>>> bmwg@ietf.org > > >>>>> > > >>>> > > >> > > https://urldefense.com/v3/__https://www.ietf.org/mailman/listinfo/bmwg__ > ;! > > >>>> > > !BhdT!1uRJDJBUadSunB4ZCkgOTzg3ZssPtiufcyrsTcxEc1F67df5q4YNUa9IYHacnsA$ > > >>> > > > > >
- [bmwg] Martin Duke's Discuss on draft-ietf-bmwg-b… Martin Duke via Datatracker
- Re: [bmwg] Martin Duke's Discuss on draft-ietf-bm… MORTON, ALFRED C (AL)
- Re: [bmwg] Martin Duke's Discuss on draft-ietf-bm… Scott O. Bradner
- Re: [bmwg] Martin Duke's Discuss on draft-ietf-bm… MORTON, ALFRED C (AL)
- Re: [bmwg] Martin Duke's Discuss on draft-ietf-bm… Scott O. Bradner
- Re: [bmwg] Martin Duke's Discuss on draft-ietf-bm… MORTON, ALFRED C (AL)
- Re: [bmwg] Martin Duke's Discuss on draft-ietf-bm… Scott O. Bradner
- Re: [bmwg] Martin Duke's Discuss on draft-ietf-bm… MORTON, ALFRED C (AL)
- Re: [bmwg] Martin Duke's Discuss on draft-ietf-bm… Martin Duke