Re: [Bier] BIER/IPv6 Requirements and Solutions

Gyan Mishra <hayabusagsm@gmail.com> Fri, 25 September 2020 17:09 UTC

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From: Gyan Mishra <hayabusagsm@gmail.com>
Date: Fri, 25 Sep 2020 13:08:54 -0400
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To: gjshep@gmail.com
Cc: Alvaro Retana <aretana.ietf@gmail.com>, "Gengxuesong (Geng Xuesong)" <gengxuesong@huawei.com>, "Jeffrey (Zhaohui) Zhang" <zzhang@juniper.net>, "Xiejingrong (Jingrong)" <xiejingrong@huawei.com>, "bier-chairs@ietf.org" <bier-chairs@ietf.org>, "bier@ietf.org" <bier@ietf.org>, "draft-ietf-bier-ipv6-requirements@ietf.org" <draft-ietf-bier-ipv6-requirements@ietf.org>
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Subject: Re: [Bier] BIER/IPv6 Requirements and Solutions
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Hi Greg

In-line

On Fri, Sep 25, 2020 at 10:41 AM Greg Shepherd <gjshep@gmail.com> wrote:

> Xuesong,
>
> Inline:
>
> On Thu, Sep 24, 2020 at 8:09 PM Gengxuesong (Geng Xuesong) <
> gengxuesong@huawei.com> wrote:
>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> Just one more comment: Any WG feedback is welcome. All the previous
>> comments are carefully considered and discussed among authors[*]. If there
>> is something
>>
>> new, raise it up with implementable operations and it will be addressed.
>> (Unless I'm missing something, section 3 hasn’t been asked to be removed or
>> even considered inappropriate until version 07 was published in my
>> knowledge)
>>
>
> There was no 'solution comparison' section in rev 0. It appeared in rev1,
> and at the end of the doc. Since then that section has been carefully
> word-smithed to direct the conversation about the requirements themselves.
> It was removed in rev 4 at the request of the WG. Then it reappeared in rev
> 6 - without any WG request - and promoted to the top of the document, no
> longer hiding the authors intent of leading the conversation on
> requirements. So yes, nobody asked to remove it since rev 4 since it was no
> longer there. As soon as it reappeared, the authors were asked to remove
> it. Nothing new here except the authors' increasing pressure to resist
> input from the WG.
>
> Please remove that section rev the draft. There is nothing more to discuss
> until then.
>
> Thanks,
> - Chairs
> (Shep)
>
>

I just went through all the versions to see where section 3 is added or
omitted below:

Rev 0 - omitted
Rev 1 - omitted
Rev 2 and 3 - appears in 5.4 5.5 I think that is what you ar talking about
word smithing ..
Rev 4 omitted
Rev 5-7 - added back
Rev 8 - moved to appendix

Based on the above we will  remove section 3 from the appendix.

Since the solutions drafts themselves speak for the solutions in detail I
think we can focus strictly on the requirements in this draft as Greg, Tony
and Alvaro stated.

Greg -  I was not aware of the details history of what transpired early
this year with the few revisions prior to me joining as author.  I will
work with the team to right the ship remain steadfast on the requirements.

Thanks

Gyan



>>
>> Xuesong
>>
>>
>>
>>
>>
>> [*]Here are all the comments we have received from WG since IETF 108
>> (most recent comments not inluded). Here are some explanations about how we
>> address/consider
>>
>> these comments in version 07.
>>
>>
>>
>>
>>
>> 1.      Comments from Greg Shepherd
>>
>>
>> Section 2 Problem Statement
>>
>>
>> -        “IPv6 unicast technologies can support multi-point transport”
>> seems not clear
>>
>>
>> [New Version] This sentence has been removed
>>
>>
>>
>>
>>
>> Section 3.2 Naive IPv6 Model
>>
>>
>> -  “BIER is integrated into the IPv6 data plane” is not precise, could be
>> considered to modify as “BIER header integrated into the IPv6 header”
>>
>>
>> [New Version] Similar expressions are maintained in this version,
>> including:
>>
>>
>> “   The second conceptual model is an Integrated Model that integrates
>>
>>
>>    BIER as part of the IPv6 data plane, making it a "Layer-3 BIER"
>>
>>
>>    approach.”
>>
>>
>> “In this model, BIER works as part of the IPv6 data plane.”
>>
>>
>> This has been discussed among the authors. If we take it narrowly, “IPv6
>> data plane” may mean to look up IP routing table and find the next hop, in
>> which case,
>>
>> BIER could not be treated as part of it; while if we take it broadly,
>> “IPv6 data plane” may include all the forwarding behavior happening in IPv6
>> layer including parsing extension headers, in which case, BIER could be
>> treated as part of it.
>>
>>
>>
>>
>>
>> 2.      Comments from Sandy Zhang:
>>
>>
>> Section 2 problem statement
>>
>>
>> -        Not only non-BFR node scenario should be included
>>
>>
>> [New version] It has been covered in the new version by
>>
>>
>>
>> “It may
>>
>>
>>    also be desirable to not use IPv6 encapsulation except when IPv6
>>
>>
>>    tunneling (native or GRE/UDP-like) is used to transport BIER packets
>>
>>
>>    over BIER-incapable routers.”
>>
>>
>>
>>
>>
>> Section 3.1
>>
>>
>> -        There is no fragmentation or IPSEC executed in BFR
>>
>>
>> [New Version]
>>
>>
>> An example has been added in section 4.2.1 to clarify the case and fix
>> the comments.
>>
>>
>>
>>
>>
>>
>> Section 3.2
>>
>>
>> -        Fast forwarding could not be supported if using IPv6 extension
>> header
>>
>>
>> -        How to deal with the relationship with other extension header,
>> e.g., fragmentation header
>>
>>
>> [New version]
>>
>>
>> This will be defined in the solution document rather than the requirement
>> document.
>>
>>
>>
>>
>>
>> 3.      Comments from Jeffrey Zhang:
>>
>>
>> Section 2  Problem Statement -> Request to remove/modify the descriptions
>> that may be considered biased:
>>
>>
>> -        Inter-domain is not model specific. Reference to individual
>> draft should be removed.
>>
>>
>> [New version]
>>
>>
>> Descriptions about Inter-domain has been removed.
>>
>>
>> -        The descriptions of fragmentation is not reasonable because
>> fragmentation/reassembly does not happen on each BFR when it is connected
>> directly with
>>
>> another BFR.
>>
>>
>> [New version]
>>
>>
>> Descriptions about fragmentation in section 3 has been removed.
>>
>>
>> -        IPv6 native functions should not be requested by Layer2.5
>> tunneling, which could be executed in IPv6 layer.
>>
>>
>> [New version]
>>
>>
>> Descriptions about other IPv6 functions in section 3 have been removed.
>>
>>
>> Section 4.1.6  Simple Encapsulation-> Unclear requirement item
>>
>>
>> [New version]
>>
>>
>> This requirement has been removed.
>>
>>
>>
>>
>>
>> 4.      Comments from Alvaro Retana
>>
>>
>> Section 2
>>
>>
>> -        Problem Statement should be straight forward
>>
>>
>> [New version]
>>
>>
>> Problem Statement has been modified totally with help of Gyan and Jeffrey.
>>
>>
>>
>>
>>
>> Section 3
>>
>>
>>
>> -        Transport-Independent Model" is not in line with the layering
>> model from rfc8279
>>
>>
>> [New version]
>>
>>
>> The layering of BIER defined in RFC8279 is not the same as it has been
>> discussed in section 3, where layer 3/layer 2.5 means protocol layering of
>> TCP/IP.
>>
>>
>> -        It seems that there is some Bias for native IPv6 Model
>>
>>
>> [New version]
>>
>>
>> Section 3.1.  Independent Model has been well modified by Jeffrey as the
>> one of the main authors of the document of BIERin6.
>>
>>
>>
>>
>>
>> Section 4
>>
>>
>> -        Three levels: required, recommended, and optional
>>
>>
>> -        Some mandatory requirements need no explanation, including:
>> Support BIER architecture; Conform to existing IPv6 Spec; Support
>> deployment with Non-BFR
>>
>> routers)
>>
>>
>> -        Some of the requirements are not clear, e.g., L2 Agnostic,
>> Support Simple Encapsulation, Support Deployment Security
>>
>>
>> -        Some of the requirements are not included in RFC8279, e.g.,
>> Support inter-AS multicast deployment
>>
>>
>> [New version]
>>
>>
>> All the requirement items have been reorganized. Well known requirement
>> is kept simple and optional requirement is justified with example.
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> -----Original Message-----
>>
>>
>> From: Greg Shepherd [mailto:gjshep@gmail.com]
>>
>>
>> Sent: Thursday, September 24, 2020 10:44 PM
>>
>>
>> To: Jeffrey (Zhaohui) Zhang <zzhang@juniper.net>
>>
>>
>> Cc: Gyan Mishra <hayabusagsm@gmail.com>; Xiejingrong (Jingrong) <
>> xiejingrong@huawei.com>; draft-ietf-bier-ipv6-requirements@ietf.org;
>> bier-chairs@ietf.org; bier@ietf.org; Alvaro Retana <
>> aretana.ietf@gmail.com>
>>
>>
>> Subject: Re: [Bier] BIER/IPv6 Requirements and Solutions
>>
>>
>>
>>
>>
>> The authors were ask to remove the comparison section. I'm asking you
>> again. I'll wait for the next rev to comment.
>>
>>
>>
>>
>>
>> Thanks,
>>
>>
>> Greg
>>
>>
>>
>>
>>
>> On Thu, Sep 24, 2020 at 2:44 AM Jeffrey (Zhaohui) Zhang <
>> zzhang@juniper.net>
>>
>>
>> wrote:
>>
>>
>>
>>
>>
>> > Hi Gyan,
>>
>>
>> >
>>
>>
>> >
>>
>>
>> >
>>
>>
>> > A small clarification – while the requirements draft -07 currently
>>
>>
>>
>> > does have sections that briefly describe different models/solutions,
>>
>>
>>
>> > we have avoided discussing which one satisfies which requirements
>>
>>
>>
>> > intentionally (as the focus is on listing requirements).
>>
>>
>> >
>>
>>
>> >
>>
>>
>> >
>>
>>
>> > With that, I don’t think we’ve got a conclusion
>>
>> that “BIER-MPLS &
>>
>>
>>
>> > BIER-Ethernet, as it stands today has a MAJOR gap in being able to
>>
>>
>>
>> > support
>>
>>
>> > SRv6 Service Provider core technology requiring an IPv6 data plane”.
>>
>>
>> >
>>
>>
>> >
>>
>>
>> >
>>
>>
>> > Jeffrey
>>
>>
>> >
>>
>>
>> >
>>
>>
>> >
>>
>>
>> >
>>
>>
>> >
>>
>>
>> > Juniper Business Use Only
>>
>>
>> >
>>
>>
>> > *From:* Gyan Mishra <hayabusagsm@gmail.com>
>>
>>
>> > *Sent:* Thursday, September 24, 2020 1:40 AM
>>
>>
>> > *To:* Greg Shepherd <gjshep@gmail.com>
>>
>>
>> > *Cc:* Xiejingrong (Jingrong) <xiejingrong@huawei.com>;
>>
>>
>>
>> >
>>
>> draft-ietf-bier-ipv6-requirements@ietf.org;
>>
>> bier-chairs@ietf.org;
>>
>>
>>
>> > bier@ietf.org; Alvaro Retana <aretana.ietf@gmail.com>
>>
>>
>> > *Subject:* Re: [Bier] BIER/IPv6 Requirements and Solutions
>>
>>
>> >
>>
>>
>> >
>>
>>
>> >
>>
>>
>> > *[External Email. Be cautious of content]*
>>
>>
>> >
>>
>>
>> >
>>
>>
>> >
>>
>>
>> > Greg
>>
>>
>> >
>>
>>
>> >
>>
>>
>> >
>>
>>
>> > With all do respect, the authors welcome the AD and Chairs criticism
>>
>>
>>
>> > and any feedback, however in this particular case with your response,
>>
>>
>>
>> > there seems to be a disconnect with the ML discussions we have had
>>
>>
>>
>> > over the last several months.  Understandably, all of us here in the
>>
>>
>>
>> > WG realize the criticality of the BIER in an IPv6 environment, and
>>
>>
>>
>> > that BIER-MPLS & BIER-Ethernet, as it stands today has a MAJOR gap in
>>
>>
>>
>> > being able to support
>>
>>
>> > SRv6 Service Provider core technology requiring an IPv6 data plane,
>>
>>
>>
>> > which will be the end all be all replacement for MPLS.  It is critical
>>
>>
>>
>> > that the BIER WG come up with a solution(s) that supports an IPv6 data
>>
>>
>>
>> > plane for
>>
>>
>> > SRv6 support.  We all don't want BIER to die on the vine in a
>>
>>
>>
>> > technology graveyard with ATM, Frame Relay and the likes.  We the
>>
>>
>>
>> > authors are all in agreement and running fast after that goal and
>>
>>
>>
>> > understand the AD & Chairs now emphasis on the requirements draft.  We
>>
>>
>>
>> > are with you lock, stock and barrel.
>>
>>
>> >
>>
>>
>> >
>>
>>
>> >
>>
>>
>> > The authors of the BIER IPv6 Solutions draft
>>
>>
>>
>> > “draft-xie-bier-ipv6-encapsulation-08”,
>>
>> BIERv6, referred to as the
>>
>>
>> > “Integrated model”, authors myself, McBride,
>>
>> Xuesong & Jingrong
>>
>>
>> > collaborated in a joint effort over a month timeframe with the authors
>>
>>
>>
>> > of the BIER IPv6 Solutions draft
>>
>> “draft-zhang-bier-bierin6-07”,
>>
>>
>>
>> > BIERin6, referred to as the Independent model , authors Jeffrey &
>>
>>
>>
>> > Sandy to come up with a holistic solution where both conceptual models
>>
>>
>>
>> > accurately addressed the problem statement as well as the requirements
>>
>>
>>
>> > to support IPv6 for SRv6 support.  We wanted to make sure that we had
>>
>>
>>
>> > complete parity between conceptual models and relationships to the
>>
>>
>>
>> > problem statement and requirements list.  All authors from both
>>
>>
>>
>> > solutions worked together to ensure we had all of our
>>
>> “i’s”
>>
>> dotted &
>>
>>
>> > “t’s”
>>
>> crossed so to speak, putting our best foot forward with this rev 7.
>>
>>
>> >
>>
>>
>> >
>>
>>
>> >
>>
>>
>> > I would like to point out that given the
>>
>> “Integrated model” BIERv6
>>
>>
>>
>> > Solutions initial draft came out in April 2018, and the
>>
>> “Independent model”
>>
>>
>> > BIERin6 Solution came out in October 2017.  It is only since January
>>
>>
>>
>> > 2019 initial draft submission has the work to reverse engineer to come
>>
>>
>>
>> > up with the Requirements draft started a
>>
>> “post mortem” so to speak
>>
>>
>>
>> > after the Solutions had already been proposed.  To that end in
>>
>>
>>
>> > IETF108, the requirements draft had positive feedback related to
>>
>>
>>
>> > Section 3 conceptual framework for the two solutions proposed.  We are
>>
>>
>>
>> > all at a loss in understanding your comments as to removal of section
>>
>>
>>
>> > 3.  In order to create a requirements draft as part of any basic
>>
>>
>>
>> > requirements analysis, you must have some idea or concept or inkling
>>
>>
>>
>> > of a solutions framework to graft & glean the list of requirements
>> which otherwise is not possible in my mind
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
> --

<http://www.verizon.com/>

*Gyan Mishra*

*Network Solutions A**rchitect *



*M 301 502-134713101 Columbia Pike *Silver Spring, MD