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

Alia Atlas <akatlas@gmail.com> Tue, 20 February 2018 18:39 UTC

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From: Alia Atlas <akatlas@gmail.com>
Date: Tue, 20 Feb 2018 13:39:23 -0500
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To: "Acee Lindem (acee)" <acee@cisco.com>
Cc: "Peter Psenak (ppsenak)" <ppsenak@cisco.com>, BIER WG <bier@ietf.org>, "isis-wg@ietf.org list" <isis-wg@ietf.org>
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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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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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