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

Bob Hinden <bob.hinden@gmail.com> Wed, 04 September 2019 00:08 UTC

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From: Bob Hinden <bob.hinden@gmail.com>
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Date: Tue, 3 Sep 2019 17:07:57 -0700
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Cc: Bob Hinden <bob.hinden@gmail.com>, 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>
To: "Templin (US), Fred L" <Fred.L.Templin@boeing.com>
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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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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.

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
>>>>> 
>>>> 
>>>> _______________________________________________
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