Re: [Pce] **Barry Leiba's DISCUSS on draft-ietf-pce-stateful-pce-auto-bandwidth**

Dhruv Dhody <dhruv.ietf@gmail.com> Tue, 17 September 2019 05:29 UTC

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From: Dhruv Dhody <dhruv.ietf@gmail.com>
Date: Tue, 17 Sep 2019 10:59:17 +0530
Message-ID: <CAB75xn4UCEXLuw-E10i=cYpphhReYwhHBGPzR=qGyiSQVstoOg@mail.gmail.com>
To: Farrel Adrian <adrian@olddog.co.uk>
Cc: Barry Leiba <barryleiba@computer.org>, pce@ietf.org, The IESG <iesg@ietf.org>, pce-chairs <pce-chairs@ietf.org>, draft-ietf-pce-stateful-pce-auto-bandwidth@ietf.org
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Subject: Re: [Pce] **Barry Leiba's DISCUSS on draft-ietf-pce-stateful-pce-auto-bandwidth**
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Hi All,

Thanks for the discussion. I have updated text based on Adrian's suggestion.

See diff - https://tools.ietf.org/tools/rfcdiff/rfcdiff.pyht?url1=draft-ietf-pce-stateful-pce-auto-bandwidth-11&url2=https://raw.githubusercontent.com/dhruvdhody/ietf/master/draft-ietf-pce-stateful-pce-auto-bandwidth-12.txt

Skip to Section 5.7 to see related changes.

Let me know if any further changes are needed.

Thanks!
Dhruv

On Mon, Sep 16, 2019 at 9:46 PM Adrian Farrel <adrian@olddog.co.uk> wrote:
>
> Yes, that's a reasonable request.
>
> Should send a Notification.
> If congested or would only serve to increase overload, May choose to not send a Notification.
> Not sending a Notification could result in foo
> A PCC experiencing foo should to bar.
> Note that when a PCE serves very many PCCs, congestion may arise without any one PCC becoming aware of multiple unserved messages, in which case something.
>
> Adrian
>
> -----Original Message-----
> From: Barry Leiba <barryleiba@computer.org>
> Sent: 16 September 2019 17:00
> To: Dhruv Dhody <dhruv.ietf@gmail.com>
> Cc: pce@ietf.org; The IESG <iesg@ietf.org>rg>; pce-chairs <pce-chairs@ietf.org>rg>; Farrel Adrian <adrian@olddog.co.uk>uk>; draft-ietf-pce-stateful-pce-auto-bandwidth@ietf.org
> Subject: Re: **Barry Leiba's DISCUSS on draft-ietf-pce-stateful-pce-auto-bandwidth**
>
> Thanks for the reply, Dhruv.
>
> To be clear, I am NOT suggesting changing it to MUST (though that
> could be a perfectly good outcome of the discussion).  I am suggesting
> that if it remains as SHOULD, there has to be some explanation of what
> the constraints are and what interoperability or security issues could
> arise if an implementation doesn't do it that way.
>
> Barry
>
> On Mon, Sep 16, 2019 at 4:21 AM Dhruv Dhody <dhruv.ietf@gmail.com> wrote:
> >
> > Hi again!
> >
> > On Mon, Sep 16, 2019 at 4:48 PM Dhruv Dhody <dhruv.ietf@gmail.com> wrote:
> > >
> > > Hi Barry, WG,
> > >
> > > I saw the DISCUSS [1] in the datatracker but for some reason the email
> > > never landed in my inbox or the list [2]. I am manually posting it
> > > here -
> > >
> > > ====
> > >
> > > Discuss (2019-09-16)
> > >
> > > Thanks for another clear document.  There are some "SHOULD" key words
> > > in one section that I would like to discuss, and that I think we ought
> > > to be able to resolve without much difficulty:
> > >
> > > — Section 5.7 —
> > >
> > > There are various “SHOULD”s in this section, and I have the same
> > > comment about all of them: BCP 14 says, about “SHOULD”, that “there
> > > may exist valid reasons in particular circumstances to ignore a
> > > particular item, but the full implications must be understood and
> > > carefully weighed before choosing a different course.”  I see no
> > > guidance here to help the reader understand what such circumstances
> > > and implications are, so I can’t see how an implementer can evaluate
> > > the situation.  Can you provide any help here?
> > >
> > > ====
> > >
> >
> > I checked the base RFC for PCEP - RFC 5440 where notifications are
> > first defined. They do not use MUST for sending notification in the
> > PCE overload case [1].
> >
> > Leaving that aside, in case of auto-bandwidth feature, this
> > notification is important for scaling. I am inclined to change it to
> > MUST as suggested.
> >
> > Co-authors, WG, please speak up if you disagree!!
> >
> > I have incorporated all other comments in the working copy.
> >
> > Diff: https://tools.ietf.org/tools/rfcdiff/rfcdiff.pyht?url1=draft-ietf-pce-stateful-pce-auto-bandwidth-11&url2=https://raw.githubusercontent.com/dhruvdhody/ietf/master/draft-ietf-pce-stateful-pce-auto-bandwidth-12.txt
> >
> > Thanks!
> > Dhruv
> >
> > [1] https://tools.ietf.org/html/rfc5440#section-7.14
> >
> > > Comment (2019-09-16)
> > >
> > > Again, these are purely editorial comments, which need no detailed
> > > response; please just consider them.
> > >
> > > — Section 1 —
> > >
> > >    Over time, based on the varying traffic pattern, an LSP established
> > >    with a certain bandwidth may require to adjust the bandwidth reserved
> > >    in the network dynamically.
> > >
> > > “may require adjustment of the bandwidth”
> > >
> > >    This is similar to
> > >    the Passive stateful PCE model, while the Passive stateful PCE uses
> > >    path request/reply mechanism, the Active stateful PCE uses
> > >    report/update mechanism.
> > >
> > > NEW
> > >    This is similar to
> > >    the Passive stateful PCE model: while the Passive stateful PCE uses
> > >    a path request/reply mechanism, the Active stateful PCE uses a
> > >    report/update mechanism.
> > > END
> > >
> > >    This document defines the PCEP extensions needed to support Auto-
> > >    Bandwidth feature in a Active stateful PCE model
> > >
> > > NEW
> > >    This document defines the PCEP extensions needed to support an Auto-
> > >    Bandwidth feature in an Active stateful PCE model
> > > END
> > >
> > > — Section 2.3 —
> > >
> > >       This value indicates how many times
> > >       consecutively, the percentage or absolute difference
> > >
> > > Add a comma after “times”.
> > >
> > > — Section 3 —
> > >
> > >    The PCEP speaker supporting this document must have a mechanism
> > >
> > > “A PCEP speaker”.
> > >
> > >    o  It is required to identify and inform the PCC, which LSPs are
> > >       enabled with Auto-Bandwidth feature.  Not all LSPs in some
> > >       deployments would like their bandwidth to be dependent on the
> > >       real-time bandwidth usage but be constant as set by the operator.
> > >
> > > NEW
> > >    o  It is necessary to identify and inform the PCC which LSPs have
> > >       the Auto-Bandwidth feature enabled.  In some deployments, not
> > >       all LSPs would like their bandwidth to be dependent on the
> > >       real-time bandwidth usage, but would rather be constant as set
> > >       by the operator.
> > > END
> > >
> > > — Section 4.1 —
> > >
> > >    The initial LSP bandwidth can be set to an arbitrary value (including
> > >    zero), in practice, it can be operator expected value based on design
> > >    and planning.
> > >
> > > NEW
> > >    The initial LSP bandwidth can be set to an arbitrary value (including
> > >    zero).  In practice, it can be set to an expected value based on design
> > >    and planning.
> > > END
> > >
> > > — Section 4.2 —
> > >
> > >    When the Auto-Bandwidth feature is enabled, the measured traffic rate
> > >    is periodically sampled at each Sample-Interval (which can be
> > >    configured by an operator and the default value as 5 minutes) by the
> > >    PCC, when the PCC is the head-end node of the LSP.  The traffic rate
> > >    samples are accumulated over the Adjustment-Interval period (in the
> > >    Up or Down direction) (which can be configured by an operator and the
> > >    default value as 24 hours).
> > >
> > > NEW
> > >    When the Auto-Bandwidth feature is enabled, the measured traffic rate
> > >    is periodically sampled at each Sample-Interval by the PCC, when the
> > >    PCC is the head-end node of the LSP.  The sample interval can be
> > >    configured by an operator, with a default value of 5 minutes.
> > >
> > >    The traffic rate samples are accumulated over the Adjustment-Interval
> > >    period (in the Up or Down direction).  The period can be configured by
> > >    an operator, with a default value of 24 hours.
> > > END
> > >
> > >    The PCC, in-charge of calculating the
> > >    bandwidth to be adjusted, can decide to adjust the bandwidth
> > >
> > > Remove both commas.
> > >
> > >    Only if the difference between the
> > >    current bandwidth demand (MaxAvgBw) and the current bandwidth
> > >    reservation is greater than or equal to the Adjustment-Threshold
> > >    (percentage or absolute value) (which can be configured by an
> > >    operator and the default as 5 percentage), the LSP bandwidth is
> > >    adjusted (upsized) to the current bandwidth demand (MaxAvgBw).
> > >
> > > I’m sorry: I can’t made any sense out of this text and, thus, can’t
> > > suggest a fix.  Please try rephrasing this.  When you do, please make
> > > it more than one sentence, and please avoid consecutive parenthesized
> > > phrases, which are awkward.
> > >
> > >    However, longer
> > >    adjustment-interval can result in an undesirable effect
> > >
> > > “a longer”
> > >
> > >    To avoid this, the
> > >    Auto-Bandwidth feature may pre-maturely expire the adjustment-
> > >    interval and adjust the LSP bandwidth
> > >
> > > “prematurely”, with no hyphen.
> > > “adjustment interval”, with no hyphen.
> > >
> > > — Section 5.1 —
> > >
> > >    o  The PCEP speaker that does not recognize the extensions defined in
> > >
> > > “A PCEP speaker”
> > >
> > >    o  If the PCEP speaker that supports the extensions defined in this
> > >
> > > “If a PCEP speaker supports”
> > >
> > > — Section 5.2 —
> > >
> > >    Future specification can define additional sub-TLVs.
> > >
> > > “specifications”
> > >
> > >    If sub-TLVs are not present, the
> > >    default values as specified in this document are used or otherwise
> > >    based on the local policy are assumed.
> > >
> > > I can’t make sense of that sentence; please re-phrase it.
> > >
> > > — Section 5.2.3.2 —
> > >
> > >    o  Reserved: SHOULD be set to zero on transmission and MUST be
> > >       ignored on receipt.
> > >
> > > Why is this “SHOULD”, when other reserved values have been “MUST”?
> > >
> > > (Same comment in 5.2.3.4, 5.2.5.1, 5.2.5.2, 5.2.5.3, and 5.2.5.4.)
> > >
> > > ====
> > >
> > > [1] https://datatracker.ietf.org/doc/draft-ietf-pce-stateful-pce-auto-bandwidth/ballot/
> > > [2] https://mailarchive.ietf.org/arch/browse/pce/
>