Re: [Int-area] Alissa Cooper's No Objection on draft-ietf-intarea-frag-fragile-16: (with COMMENT)

"Templin (US), Fred L" <Fred.L.Templin@boeing.com> Wed, 04 September 2019 14:23 UTC

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From: "Templin (US), Fred L" <Fred.L.Templin@boeing.com>
To: Bob Hinden <bob.hinden@gmail.com>
CC: Tom Herbert <tom@herbertland.com>, "int-area@ietf.org" <int-area@ietf.org>, IESG <iesg@ietf.org>, Joel Halpern <joel.halpern@ericsson.com>, "draft-ietf-intarea-frag-fragile@ietf.org" <draft-ietf-intarea-frag-fragile@ietf.org>, "intarea-chairs@ietf.org" <intarea-chairs@ietf.org>
Thread-Topic: [Int-area] Alissa Cooper's No Objection on draft-ietf-intarea-frag-fragile-16: (with COMMENT)
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Date: Wed, 4 Sep 2019 14:23:29 +0000
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Subject: Re: [Int-area] Alissa Cooper's No Objection on draft-ietf-intarea-frag-fragile-16: (with COMMENT)
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Bob,

> -----Original Message-----
> From: Bob Hinden [mailto:bob.hinden@gmail.com]
> Sent: Tuesday, September 03, 2019 5:08 PM
> To: Templin (US), Fred L <Fred.L.Templin@boeing.com>
> Cc: Bob Hinden <bob.hinden@gmail.com>om>; Tom Herbert <tom@herbertland.com>om>; int-area@ietf.org; IESG <iesg@ietf.org>rg>; Joel
> Halpern <joel.halpern@ericsson.com>om>; draft-ietf-intarea-frag-fragile@ietf.org; intarea-chairs@ietf.org
> Subject: Re: [Int-area] Alissa Cooper's No Objection on draft-ietf-intarea-frag-fragile-16: (with COMMENT)
> 
> Fred,
> 
> > On Sep 3, 2019, at 2:10 PM, Templin (US), Fred L <Fred.L.Templin@boeing.com> wrote:
> >
> > Bob,
> >
> >> -----Original Message-----
> >> From: Bob Hinden [mailto:bob.hinden@gmail.com]
> >> Sent: Tuesday, September 03, 2019 1:57 PM
> >> To: Tom Herbert <tom@herbertland.com>
> >> Cc: Bob Hinden <bob.hinden@gmail.com>om>; Templin (US), Fred L <Fred.L.Templin@boeing.com>om>; int-area@ietf.org; IESG
> >> <iesg@ietf.org>rg>; Joel Halpern <joel.halpern@ericsson.com>om>; draft-ietf-intarea-frag-fragile@ietf.org; intarea-chairs@ietf.org
> >> Subject: Re: [Int-area] Alissa Cooper's No Objection on draft-ietf-intarea-frag-fragile-16: (with COMMENT)
> >>
> >> Tom,
> >>
> >>> On Sep 3, 2019, at 1:33 PM, Tom Herbert <tom@herbertland.com> wrote:
> >>>
> >>> Bob,
> >>>
> >>> I agree with Fred. Note, the very first line of the introduction:
> >>>
> >>> "Operational experience [Kent] [Huston] [RFC7872] reveals that IP
> >>> fragmentation introduces fragility to Internet communication”.
> >>
> >> Yes, that text in in the first paragraph of the Introduction
> >>>
> >>> This attempts to frame fragmentation as being generally fragile with
> >>> supporting references. However, there was much discussion on the list
> >>> about operational experience that demonstrates fragmentation is not
> >>> fragile. In particular, we know that fragmentation with tunnels is
> >>> productively deployed and has been for quite some time. So that is the
> >>> counter argument to the general statement that fragmentation is
> >>> fragile. With the text about tunneling included in the introduction I
> >>> believe that was sufficient balance of the arguments, but without the
> >>> text the reader could be led to believe that fragmentation is fragile
> >>> for everyone all the time which is simply not true and would be
> >>> misleading.
> >>
> >> Yes, but we are discussing some text from the Introduction that to my read didn’t say anything useful so I removed it.  The
> substantive
> >> text about tunneling in in Section 3.5.  The Introduction, is just the introduction.  The text was:
> >>
> >>   This document acknowledges that in some cases, packets must be
> >>   fragmented within IP-in-IP tunnels [I-D.ietf-intarea-tunnels].
> >>   Therefore, this document makes no additional recommendations
> >>   regarding IP-in-IP tunnels.
> >
> > Yes - good text that should be retained.
> >
> >> Why is that more useful than what is in 3.5? If it’s not making a recommendation, why call this out in the introduction.  There are lot
> of
> >> other things it doesn’t make recommendations about that aren’t in the Introduction either.
> >
> > Because it sets a more appropriate tone and lets the reader know from the onset that
> > fragmentation and encapsulation go hand in hand. And tunnel fragmentation avoids the
> > issues raised by others in this thread.
> 
> I don’t know how to evaluate “tone” in an IETF specification.
> 
> How about if I move this text to section 5.3?  I think that’s better than in the Introduction.
> 
> The section would be:
> 
>    5.3.  Packet-in-Packet Encapsulations
> 
>    This document acknowledges that in some cases, packets must be
>    fragmented within IP-in-IP tunnels.  Therefore, this document makes no
>    additional recommendations regarding IP-in-IP tunnels.
> 
>    In this document, packet-in-packet encapsulations include IP-in-IP
>    [RFC2003], Generic Routing Encapsulation (GRE) [RFC2784], GRE-in-UDP
>    [RFC8086] and Generic Packet Tunneling in IPv6 [RFC2473].  [RFC4459]
>    describes fragmentation issues associated with all of the above-
>    mentioned encapsulations.
> 
>    The fragmentation strategy described for GRE in [RFC7588] has been
>    deployed for all of the above-mentioned encapsulations.  This
>    strategy does not rely on IP fragmentation except in one corner case.
>    (see Section 3.3.2.2 of RFC 7588 and Section 7.1 of RFC 2473).
>    Section 3.3 of [RFC7676] further describes this corner case.
> 
>    See [I-D.ietf-intarea-tunnels] for further discussion.

Paragraph #1 beginning "This document acknowledges" looks good, but then
why include paragraphs #2 and #3 since 'intarea-tunnels' is the place to discuss
IP-in-IP encapsulation. So, why not shorten Section 5.3 and have it as simply:

   5.3.  Packet-in-Packet Encapsulations

   This document acknowledges that in some cases, packets must be
   fragmented within IP-in-IP tunnels.  Therefore, this document makes no
   additional recommendations regarding IP-in-IP tunnels.
   See [I-D.ietf-intarea-tunnels] for further discussion.

Fred

> Bob
> 
> 
> >
> > Thanks - Fred
> >
> >> Bob
> >>
> >>>
> >>> Speaking of balance, the introduction also mentions that:
> >>>
> >>> "this document recommends that upper-layer protocols address the
> >>> problem of fragmentation at their layer"
> >>>
> >>> But the "problem" of fragmentation is in intermediate devices that
> >>> don't properly handle it as the draft highlights. So it seems like
> >>> part of addressing the problem should also be to fix the problem! That
> >>> is implementations should be fixed to deal with fragmentation. IMO,
> >>> this should be another high level recommendation that is mentioned in
> >>> the introduction.
> >>
> >> I am serving as document editor.  This to my understanding has been through w.g. last call and now IESG review.
> >>>
> >>> Tom
> >>>
> >>>
> >>>
> >>> Tom
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> On Tue, Sep 3, 2019 at 1:01 PM Bob Hinden <bob.hinden@gmail.com> wrote:
> >>>>
> >>>> Fred,
> >>>>
> >>>>> On Sep 3, 2019, at 12:45 PM, Templin (US), Fred L <Fred.L.Templin@boeing.com> wrote:
> >>>>>
> >>>>> Bob,
> >>>>>
> >>>>>> -----Original Message-----
> >>>>>> From: Bob Hinden [mailto:bob.hinden@gmail.com]
> >>>>>> Sent: Tuesday, September 03, 2019 9:10 AM
> >>>>>> To: Templin (US), Fred L <Fred.L.Templin@boeing.com>
> >>>>>> Cc: Bob Hinden <bob.hinden@gmail.com>om>; Joe Touch <touch@strayalpha.com>om>; Alissa Cooper <alissa@cooperw.in>in>; Joel
> >> Halpern
> >>>>>> <joel.halpern@ericsson.com>om>; draft-ietf-intarea-frag-fragile@ietf.org; int-area@ietf.org; IESG <iesg@ietf.org>rg>; intarea-
> >>>>>> chairs@ietf.org
> >>>>>> Subject: Re: [Int-area] Alissa Cooper's No Objection on draft-ietf-intarea-frag-fragile-16: (with COMMENT)
> >>>>>>
> >>>>>> Fred,
> >>>>>>
> >>>>>>> On Sep 3, 2019, at 7:33 AM, Templin (US), Fred L <Fred.L.Templin@boeing.com> wrote:
> >>>>>>>
> >>>>>>> Why was this section taken out:
> >>>>>>>
> >>>>>>>> 1.1.  IP-in-IP Tunnels
> >>>>>>>>
> >>>>>>>> This document acknowledges that in some cases, packets must be
> >>>>>>>> fragmented within IP-in-IP tunnels [I-D.ietf-intarea-tunnels].
> >>>>>>>> Therefore, this document makes no additional recommendations
> >>>>>>>> regarding IP-in-IP tunnels.
> >>>>>>
> >>>>>> This text in the Introduction was removed because, as noted in Warren Kumari
> >>>>>> Comment (2019-08-07 for -15), this didn’t need to be in the introduction, and it didn’t say very much that isn’t described later
> in
> >> the
> >>>>>> document.
> >>>>>>
> >>>>>> The normative text in Section 5.3. "Packet-in-Packet Encapsulations” is unchanged.  I think Section 5.3 covers the topic.  It
> >> includes the
> >>>>>> reference to [I-D.ietf-intarea-tunnels].
> >>>>>
> >>>>> While I agree that both passages supply a working vector to 'intarea-tunnels',
> >>>>> the two strike very different tones. The former gives a balanced citation, while
> >>>>> the latter calls it a "corner case" - twice!
> >>>>>
> >>>>> Whether we like it or not, fragmentation and encapsulation will continue to
> >>>>> be associated with each other no matter what gets documented here. So,
> >>>>> a respectful handoff to 'intarea-tunnels' would be appreciated.
> >>>>
> >>>> You are talking about text in the Introduction of the document.
> >>>>
> >>>> The important substance relating to tunnels is in Section 5.3.   The text is:
> >>>>
> >>>>  5.3.  Packet-in-Packet Encapsulations
> >>>>
> >>>>  In this document, packet-in-packet encapsulations include IP-in-IP
> >>>>  [RFC2003], Generic Routing Encapsulation (GRE) [RFC2784], GRE-in-UDP
> >>>>  [RFC8086] and Generic Packet Tunneling in IPv6 [RFC2473].  [RFC4459]
> >>>>  describes fragmentation issues associated with all of the above-
> >>>>  mentioned encapsulations.
> >>>>
> >>>>  The fragmentation strategy described for GRE in [RFC7588] has been
> >>>>  deployed for all of the above-mentioned encapsulations.  This
> >>>>  strategy does not rely on IP fragmentation except in one corner case.
> >>>>  (see Section 3.3.2.2 of RFC 7588 and Section 7.1 of RFC 2473).
> >>>>  Section 3.3 of [RFC7676] further describes this corner case.
> >>>>
> >>>>  See [I-D.ietf-intarea-tunnels] for further discussion.
> >>>>
> >>>> Seems fine to me, in tone and substance.
> >>>>
> >>>> Bob
> >>>>
> >>>>
> >>>>>
> >>>>> Fred
> >>>>>
> >>>>>> Bob
> >>>>>>
> >>>>>>
> >>>>>>>
> >>>>>>> Tunnels always inflate the size of packets to the point that they may exceed
> >>>>>>> the path MTU even if the original packet is no larger than the path MTU. And,
> >>>>>>> for IPv6 the only guarantee is 1280. Therefore, in order to robustly support
> >>>>>>> the minimum IPv6 MTU tunnels MUST employ fragmentation.
> >>>>>>>
> >>>>>>> Please put this section of text back in the document where it belongs.
> >>>>>>>
> >>>>>>> Thanks - Fred
> >>>>>>>
> >>>>>>>> -----Original Message-----
> >>>>>>>> From: Int-area [mailto:int-area-bounces@ietf.org] On Behalf Of Joe Touch
> >>>>>>>> Sent: Tuesday, September 03, 2019 7:06 AM
> >>>>>>>> To: Alissa Cooper <alissa@cooperw.in>
> >>>>>>>> Cc: Joel Halpern <joel.halpern@ericsson.com>om>; draft-ietf-intarea-frag-fragile@ietf.org; int-area@ietf.org; The IESG
> >>>>>> <iesg@ietf.org>rg>;
> >>>>>>>> intarea-chairs@ietf.org
> >>>>>>>> Subject: Re: [Int-area] Alissa Cooper's No Objection on draft-ietf-intarea-frag-fragile-16: (with COMMENT)
> >>>>>>>>
> >>>>>>>> Hi, all,
> >>>>>>>>
> >>>>>>>> So let me see if I understand:
> >>>>>>>>
> >>>>>>>> Alissa issues a comment.
> >>>>>>>>
> >>>>>>>> We discuss this on the list and come to a rare consensus on a way forward.
> >>>>>>>>
> >>>>>>>> The new draft is issued that:
> >>>>>>>>
> >>>>>>>> a) ignores the list consensus
> >>>>>>>> b) removes a paragraph not under the DISCUSS (1.1)
> >>>>>>>> c) now refers to vague “other documents” without citation
> >>>>>>>> d) most importantly:
> >>>>>>>>
> >>>>>>>>  REMOVES a key recommendation that we MAY use frag where it works
> >>>>>>>>
> >>>>>>>>  Asserts the false claim that IP fragmentation “will fail” in the Internet,
> >>>>>>>>  despite citing evidence that the *majority of the time* it does work
> >>>>>>>>          e.g., for IPv6, sec 3.9
> >>>>>>>>
> >>>>>>>> What happened? Why is a change this substantial not reflecting the *list consensus*?
> >>>>>>>>
> >>>>>>>> Joe
> >>>>>>>>
> >>>>>>>>> On Sep 3, 2019, at 5:59 AM, Alissa Cooper via Datatracker <noreply@ietf.org> wrote:
> >>>>>>>>>
> >>>>>>>>> Alissa Cooper has entered the following ballot position for
> >>>>>>>>> draft-ietf-intarea-frag-fragile-16: No Objection
> >>>>>>>>>
> >>>>>>>>> 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:
> >>>>>>>>> https://datatracker.ietf.org/doc/draft-ietf-intarea-frag-fragile/
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>> ----------------------------------------------------------------------
> >>>>>>>>> COMMENT:
> >>>>>>>>> ----------------------------------------------------------------------
> >>>>>>>>>
> >>>>>>>>> Thanks for addressing my DISCUSS.
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>> _______________________________________________
> >>>>>>>>> Int-area mailing list
> >>>>>>>>> Int-area@ietf.org
> >>>>>>>>> https://www.ietf.org/mailman/listinfo/int-area
> >>>>>>>>
> >>>>>>>> _______________________________________________
> >>>>>>>> Int-area mailing list
> >>>>>>>> Int-area@ietf.org
> >>>>>>>> https://www.ietf.org/mailman/listinfo/int-area
> >>>>>
> >>>>
> >>>> _______________________________________________
> >>>> Int-area mailing list
> >>>> Int-area@ietf.org
> >>>> https://www.ietf.org/mailman/listinfo/int-area
> >