Re: [Isis-wg] [Bier] BAR field length in draft-ietf-bier-isis-extensions and draft-ietf-bier-ospf-extensions

Tony Przygienda <tonysietf@gmail.com> Tue, 20 February 2018 18:41 UTC

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From: Tony Przygienda <tonysietf@gmail.com>
Date: Tue, 20 Feb 2018 10:40:21 -0800
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To: Alia Atlas <akatlas@gmail.com>
Cc: "Acee Lindem (acee)" <acee@cisco.com>, BIER WG <bier@ietf.org>, "isis-wg@ietf.org list" <isis-wg@ietf.org>, "Peter Psenak (ppsenak)" <ppsenak@cisco.com>
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Subject: Re: [Isis-wg] [Bier] BAR field length in draft-ietf-bier-isis-extensions and draft-ietf-bier-ospf-extensions
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+1 obviously ...

On Tue, Feb 20, 2018 at 10:39 AM, Alia Atlas <akatlas@gmail.com>; wrote:

> Hi Acee,
>
> Thanks for your feedback.  I appreciate and agree with the perspective.
>
> Regards,
> Alia
>
>
> On Tue, Feb 20, 2018 at 1:36 PM, Acee Lindem (acee) <acee@cisco.com>;
> wrote:
>
>> Hi Alia,
>> I support Peter's position on the draft. While I believe at 8 bit space
>> is more than enough to support  variations of the BIER algorithm for the
>> foreseeable future, I think reaching consensus is more critical than the
>> precise encoding.
>>
>> Thanks,
>> Acee
>>
>> ´╗┐On 2/20/18, 12:28 PM, "Isis-wg on behalf of Peter Psenak (ppsenak)" <
>> isis-wg-bounces@ietf.org on behalf of ppsenak@cisco.com>; wrote:
>>
>>     Hi Alia,
>>
>>     1. I see a benefit in having the BIER a way to map to any of the IGP
>>     algorithms. Simply because IGPs already provide paths to all nodes in
>>     the domain and BIER can simply use these paths instead of computing
>> its own.
>>
>>     2. Not sure if people plan to deploy the BIER in a model where it does
>>     its own topology related computations, independent of IGPs. If they
>> do,
>>     I'm not objecting that.
>>
>>     The encoding of the BAR though must be done in a way that it easily
>>     supports both (1) and (2).
>>
>>     my 2c,
>>     Peter
>>
>>
>>
>>     On 19/02/18 22:51 , Alia Atlas wrote:
>>     > As the Sponsoring AD for draft-ietf-bier-isis-extensions-07 and
>>     > draft-ietf-bier-ospf-extensions-12, I have been following the
>> discussion
>>     > on the mailing list with interest.
>>     >
>>     > I have not seen clear consensus for any change.
>>     >
>>     > Let me be clear on what I see the options are from the discussion.
>> Then
>>     > I'll elaborate
>>     > a bit on how you can express your perspective most usefully.
>>     >
>>     > 1) Current Status:  Bier Algorithm (BAR) field is 8 bits.
>> Currently,
>>     > only value 0 is specified.  The drafts do not have an IANA registry
>> -
>>     > with the expectation that one will be created when the first
>> additional
>>     > use is clear.  It is possible that there will be objections from the
>>     > IESG to progressing without an IANA registry.  Given the lack of
>> clarity
>>     > for future use-cases and after discussion, I decided not to force
>> one
>>     > after my AD review - but I will not push back against having a BIER
>> IANA
>>     > registry if raised by others.
>>     >
>>     > 2) Option B:  Add a BAR sub-type of 8 bits.  This would modify the
>>     > current TLVs.
>>     >     Define an IANA registry for the BAR type.  The meaning of the
>> BAR
>>     > sub-type derives
>>     >     from the BAR type.   We can debate over the registration policy
>> for
>>     > the BAR type.
>>     >
>>     > 3) Option C: Change the BAR field to be 16 bits and define an IANA
>>     > registry.  Part of the range can be FCFS with Expert Review, part
>> can be
>>     > Specification Required, and part can be IETF Consensus.
>>     >
>>     > 4) Option D: At some point in the future, if there is an actual
>>     > understood and documented need, a BAR sub-type could be added a
>>     > sub-TLV.  The length of the BAR sub-type could be determined when
>> the
>>     > sub-TLV is defined.
>>     >
>>     > Given
>>     >
>>     >    a) option D exists
>>     >    b) there is currently only one defined value for BAR
>>     >    c) I do not see strong consensus for change to one particular
>> other
>>     > option
>>     >
>>     > I see no current reason for a change and I certainly see absolutely
>> no
>>     > reason for
>>     > a delay in progressing the documents.
>>     >
>>     > I do want to be clear about what the WG wants to do on this issue.
>>     > Therefore, here is
>>     > my following request.
>>     >
>>     > Please send your feedback to the mailing list as follows:
>>     >
>>     > IF you prefer or can accept the current status, please say so.  No
>> more
>>     > justification
>>     > or reasoning is required. I just don't want the bulk of folks who
>> are
>>     > content to be
>>     > overlooked by those suggesting change.
>>     >
>>     > IF you prefer or can accept the current status, but think there
>> should
>>     > be an IANA registry
>>     > as is usual for managing code-points, please say so.  No more
>>     > justification is needed.
>>     >
>>     > IF you prefer Option B, C, and/or D, please say so with your
>>     > explanation.  More technical depth than "'we might need it" would be
>>     > helpful; the availability of sub-TLVs already
>>     > provides future proofing.
>>     >
>>     > IF you have a clear technical objection to why the Current Status
>> is not
>>     > acceptable,
>>     > please express that - with clear details.
>>     >
>>     > IF you feel that additional code-points should be allocated in a BAR
>>     > IANA Registry or
>>     > have thoughts on the appropriate policy, please say so with your
>>     > explanation for what
>>     > those should be.
>>     >
>>     > Unless I see clear and strong consensus for something other than the
>>     > Current Status,
>>     > that will remain.
>>     >
>>     > IF there is clear and strong consensus for Option B, C, or D, or
>> adding
>>     > an IANA registry with particular values, then it will be possible to
>>     > have a change up through this Weds night - with a 1 week WGLC on
>> that
>>     > particular technical change.
>>     >
>>     > My priority is to have the base BIER specifications published as
>>     > Proposed Standards so that more BIER implementations and deployment
>> can
>>     > be done.  I would like the WG to wrap up the core work (as
>> expressed in
>>     > the proposed recharter) so that you all can look
>>     > at how to use it.
>>     >
>>     > Given this topic was raised last Weds and given that there are no
>>     > technical objections raised to the documents as are, there isn't
>> much
>>     > time - so please just respond to this email ASAP.  My deadline for a
>>     > decision is 6pm EST on Weds.
>>     >
>>     > Regards,
>>     > Alia
>>     >
>>     >
>>     >
>>     > _______________________________________________
>>     > BIER mailing list
>>     > BIER@ietf.org
>>     > https://www.ietf.org/mailman/listinfo/bier
>>     >
>>
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