Re: [Lsr] New draft on Flex-Algorithm Bandwidth Constraints

Robert Raszuk <robert@raszuk.net> Wed, 03 March 2021 10:55 UTC

Return-Path: <robert@raszuk.net>
X-Original-To: lsr@ietfa.amsl.com
Delivered-To: lsr@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id A8C3C3A0CD2 for <lsr@ietfa.amsl.com>; Wed, 3 Mar 2021 02:55:10 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -0.856
X-Spam-Level:
X-Spam-Status: No, score=-0.856 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, HTML_MESSAGE=0.001, NUMERIC_HTTP_ADDR=1.242, 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=raszuk.net
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 wRl9U1Odeytb for <lsr@ietfa.amsl.com>; Wed, 3 Mar 2021 02:55:08 -0800 (PST)
Received: from mail-lf1-x136.google.com (mail-lf1-x136.google.com [IPv6:2a00:1450:4864:20::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 7012F3A0CCF for <lsr@ietf.org>; Wed, 3 Mar 2021 02:55:08 -0800 (PST)
Received: by mail-lf1-x136.google.com with SMTP id b1so25611543lfb.7 for <lsr@ietf.org>; Wed, 03 Mar 2021 02:55:08 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=raszuk.net; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=RmbnHYBCbLpv/sDdIWTg6Om3bv9gtjTBztz07Sny35c=; b=FFt2rJnrCUQr4FLe06rKzvDoKnFKkkmhQo5m0/cmVzd4ixthspy1yoiUr4SbbENF8z 9XiG/d8qrJHXSioIZVbcee8vpr77jkeIoOiKcdnjnU0aI3kXp0tLhEW9OplEvN/WpCKP K9kry6kB/UgFBYefY8MgtsxptFm00mw1EMrWpwPPWF/sHHXnr06fbBbuhPSwNq0+uOYF 784sQQjRNkCTgKz1lQ8GkPlY6puCDLCCQU85qkmzVw1xpLdUMW9DLV8DmrpMYz+vzyzs hBFvVnk/N5B6EzSSBcVm2dyUWO0pUFyoRP7tDHeLYlF52MCgkoMqusu69iXTJRcSsmvx Gn7g==
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=RmbnHYBCbLpv/sDdIWTg6Om3bv9gtjTBztz07Sny35c=; b=FKBFaVnfPBVPmMfKlt09+iJfPKCA7yAEepDG6tJ4QhiMRFRurFCFsRCFoWVr75ckGF 4arLK0TUCQU7zgNJ4QrlkESOWlPK5vWlNoLDrIEcqlQ/Ekz2BzevlbLQ0ZnqIv1LM/f6 Ss2+SfMRpJrIRv1aAUlRIgqfdCxKnPDSgdyKhr/+Y+TM0LBNO7VebjCaXOp1PX4t474H lAqDMyMP8CvDUgQcz/vV89flqpUy86h5xGny2zl9E8pmyTXCtoTcCCALC82c1RnK16PJ HAHTNDoLT6H76LtYfgMUX0oGfUAgNymEwGSBrRdqneJY+a7lQcANBtE/2dmxBme+deqi ndBw==
X-Gm-Message-State: AOAM530Wk6KUWZuT56/Fz4Gz6I1y2DyhCf1g4amvkgrMuqm9S6/MQ5ZI HUuh95fjj4k2HdDEKF5t/pF/8bw4Dyu41H4cj+TvCg==
X-Google-Smtp-Source: ABdhPJw4AfEetBR2qp1ayPZKWpI0jRMcPcVGzVOotmjbNEsIiB8Pu1xopWVI+QdoFt5u6PWZxqBolVKl8JZA09Z1+Hw=
X-Received: by 2002:a19:c14c:: with SMTP id r73mr15452064lff.581.1614768904156; Wed, 03 Mar 2021 02:55:04 -0800 (PST)
MIME-Version: 1.0
References: <161401476623.19237.3808413288895066510@ietfa.amsl.com> <CAOj+MMHKazMG3wnUA+Kd2wg2hfr01CdF5w5YYKdFaHU4_V+0SA@mail.gmail.com> <CABNhwV0UKB=HaMs9eLvvp4fVLPsEtJhQ2xFmwY80sqBNDFRudQ@mail.gmail.com> <DM5PR0501MB38006C4B638AD2AB6A7731B5CD9A9@DM5PR0501MB3800.namprd05.prod.outlook.com> <7C67D01F-24DB-4450-8587-E004CAFBBEBC@tony.li> <CAOj+MMGZppwYtNr4t0rJoy3BKWaBYqHiJ_esM1XNFTNxbm8c5w@mail.gmail.com> <08882555-009B-4068-ABB0-20B0D165D722@tony.li> <2c2605a8-95c6-a477-b1b5-5ae4d4de222a@cisco.com> <CAOj+MMGf=zQMGP+q+XX-MJi-qMrOddmq_+wmrXFS+JQX_PsudQ@mail.gmail.com> <25a8853a-72a3-3013-6a87-d8049ed7a3da@cisco.com> <CAOj+MMH2a=T-vBsD6QVChmybmdQhQXFcDg1np+v+bpKOWPbtKA@mail.gmail.com> <8be3198f-4c9c-2bae-9ce9-f283ac5305a1@cisco.com> <CAOj+MMFf_QymQLOG4mR9F_3h-njo0k2Le6eE1bKUkK6NmcLboQ@mail.gmail.com> <42fbaa46-7434-39fb-b5a1-97fe0c7866d3@cisco.com> <CAOj+MMG5j=HcZhtni+ROVU4zjzgHDKQhNmgxpBqpx97Jf3uU4w@mail.gmail.com> <18735f3e-9a41-5ab7-edc9-75c3ac65f8bf@cisco.com>
In-Reply-To: <18735f3e-9a41-5ab7-edc9-75c3ac65f8bf@cisco.com>
From: Robert Raszuk <robert@raszuk.net>
Date: Wed, 3 Mar 2021 11:54:52 +0100
Message-ID: <CAOj+MMEpJDMXb3STRns6zbKDtJs0Em1CBPeOPh8kseVTejBdrA@mail.gmail.com>
To: Peter Psenak <ppsenak@cisco.com>
Cc: Tony Li <tony.li@tony.li>, Gyan Mishra <hayabusagsm@gmail.com>, "DECRAENE Bruno IMT/OLN" <bruno.decraene@orange.com>, Shraddha Hegde <shraddha@juniper.net>, Rajesh M <mrajesh@juniper.net>, "lsr@ietf.org" <lsr@ietf.org>, William Britto A J <bwilliam=40juniper.net@dmarc.ietf.org>
Content-Type: multipart/alternative; boundary="000000000000ed48d905bc9faead"
Archived-At: <https://mailarchive.ietf.org/arch/msg/lsr/WWY3z7_dIQHwPtO-aV30qwQBXEU>
Subject: Re: [Lsr] New draft on Flex-Algorithm Bandwidth Constraints
X-BeenThere: lsr@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Link State Routing Working Group <lsr.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/lsr>, <mailto:lsr-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/lsr/>
List-Post: <mailto:lsr@ietf.org>
List-Help: <mailto:lsr-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/lsr>, <mailto:lsr-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 03 Mar 2021 10:55:11 -0000

Not sure what's the difference between the two.

But I guess let't wait for authors to clarify their intentions here.

Cheers,
R.

On Wed, Mar 3, 2021, 11:47 Peter Psenak <ppsenak@cisco.com> wrote:

> Robert,
>
> On 03/03/2021 11:41, Robert Raszuk wrote:
> >
> > Sorry but to me the draft is very clear that it does not care about min
> > delay, but possible maximum delay of a link  ...
>
> "maximum link delay constraint" !=  "max link delay"
>
> You are not listening.
>
> Peter
>
> >
> > After all for time sensitive applications we do care how long it will
> > take to actually traverse a path in practice not what would be the
> > theoretical min amount of time needed for this path to be traversed.
> >
> > And it does define it here as brand new metric.
> >
> > Just read this paragraph as well as sections 3.1.2 and 3.2.2.
> > <http://3.2.2.>:
> >
> >     Similarly, exclude maximum link delay constraint is also defined in
> >     this document.  Links may have the link delay measured dynamically
> >     and advertised in delay metric in IGP.  For usecases that deploy low
> >     latency flex-algo, may want to exclude links that have delay more
> >     than a defined threshold.
> >
> > Thx,
> > R.
> >
> >
> > On Wed, Mar 3, 2021 at 11:31 AM Peter Psenak <ppsenak@cisco.com
> > <mailto:ppsenak@cisco.com>> wrote:
> >
> >     On 03/03/2021 11:27, Robert Raszuk wrote:
> >      >
> >      > I am not sure I follow your logic here ...
> >      >
> >      > If we are already advertising "Min Unidirectional link delay" as
> >      > described in
> >     https://tools.ietf.org/html/draft-ietf-lsr-flex-algo-13 why
> >      > would we need to define it again here in this draft ?
> >
> >     we are not defining the metric here, we are defining the constraint
> >     that
> >     says what is the maximum value of that metric that can be used.
> >
> >     thanks,
> >     Peter
> >      >
> >      > Also does it really make sense to advertise maximum value of
> >      > minimum value ?
> >      >
> >      > Thx,
> >      > R.
> >      >
> >      > On Wed, Mar 3, 2021 at 11:22 AM Peter Psenak <ppsenak@cisco.com
> >     <mailto:ppsenak@cisco.com>
> >      > <mailto:ppsenak@cisco.com <mailto:ppsenak@cisco.com>>> wrote:
> >      >
> >      >     Robert,
> >      >
> >      >     On 03/03/2021 11:10, Robert Raszuk wrote:
> >      >      > Hey Peter,
> >      >      >
> >      >      >      > Authors stated: "Whether egress queueing delay is
> >     included
> >      >     in the
> >      >      >     link
> >      >      >      > delay depends on the measuring mechanism."
> >      >      >
> >      >      >     I disagree with that statement - the Min
> >     Unidirectional Link
> >      >     Delay is
> >      >      >     the value that does not include the queueing delay -
> >     that's
> >      >     why it is
> >      >      >     called Min.
> >      >      >
> >      >      >
> >      >      >
> >      >      > But draft we are discussing here does not talk about "Min"
> >     delay.
> >      >      > Contrary it talks about "Max"
> >      >      >
> >      >      > *Maximum*  Delay sub-TLV
> >      >      >
> >      >      > That is also I asked that very question up front.
> >      >
> >      >     I'm afraid you misunderstood it. FA uses "Min Unidirectional
> Link
> >      >     Delay"
> >      >     as one of its metrics. The "Maximum Delay sub-TLV"  is used to
> >      >     advertise
> >      >     the maximum value of the "Min Unidirectional Link Delay" that
> is
> >      >     allowed
> >      >     for the particular FA.
> >      >
> >      >     The text should be improved in that regard though, it's not
> >     obvious,
> >      >     but
> >      >     I believe that's what it is.
> >      >
> >      >     thanks,
> >      >     Peter
> >      >
> >      >      >
> >      >      > Thx,
> >      >      > R.
> >      >      >
> >      >      >
> >      >      >
> >      >      >
> >      >
> >
>
>