Re: [Bier] WGLC: draft-ietf-bier-non-mpls-bift-encoding

Hi Ice/Xiejingrong,

Yes, it is understood that "domain-wide-unique" is advantageous & simple
over "non-domain-wide-unique" BIFT-id's.

And yes, the question about "should we allow non-domain-wide-unique
BIFT-id?" is not exactly arised due to this draft. I've just used the LC
call to seek opinion on the allowing non-domain-wide-unique bift-id's :).
To support non-domain-wide-unique bift-id is based on the real use-case
requirement and i do not have one right now !

So finally to clarify my opinion, "I support WGLC" & move forward. J

Thanks,
Senthil

On Mon, Jan 28, 2019 at 4:47 PM IJsbrand Wijnands (iwijnand) <
iwijnand@cisco.com> wrote:

> Hi Senthil,
>
> Thanks for the comments.
>
> See response inline.
>
> > I believe the ‘Domain-wide unique’ is the key value of Non-MPLS
> encapsulation.
> > Allocation BIFT-id locally on each node is an extra cost, not only in
> data-plane, but also in control-plane.
> >
> > That has been concluded in RFC8296 section 2.2.1.1:
> >    In non-MPLS networks, a BIFT-id MUST be assigned for every
> >    combination of <SD, SI, BSL> that is to be used in that network.  The
> >    correspondence between a BIFT-id and a particular <SD, SI, BSL>
> >    triple is unique throughout the BIER domain and is known to all the
> >    BFRs in the BIER domain.
> >
> > The draft we are discussing is to define the above ‘correspondence’
> rule.
>
> ICE: Agree with Senthil.
>
> >
> > Support !
> > However, i would like to get couple of clarifications with respect to
> the BIFT-id in non-MPLS networks..
> >
> > 1.
> >
> > Excerpts from section 2.2.1.1 from RFC8296
> >    In an MPLS network, since the BIFT-id is an MPLS label, its value may
> >    be changed as a BIER packet goes from BFR to BFR.  In a non-MPLS
> >    network, since the BIFT-id is domain-wide unique, it is not expected
>   // Senthil
> >    to change as a BIER packet travels.
> >
> > Senthil// I believe, we do not want to mandate that the BIFT-id must be
> domain-wide-unique in case of non-MPLS networks (for the sake of
> flexibility).
> >               If its *not* domain-wide-unique, then the BIFT-id may
> change in BFR's as the BIER packet travels from BFIR to BFER.
> >               Authors & Fellow BIER'ers, let me know what do you think ?
> >
> > 2.
> >
> > draft-ietf-bier-non-mpls-bift-encoding-01 proposes two encoding methods
> for BIFT-id and is mentioned that, both of the encoding options are to
> derive "domain-wide-unique: BIFT-id's.
> >
> > I believe, option-2, that is  "6. The Non-MPLS Static IBU-SI BIFT
> Encoding", is flexible and can be used for non-domain-wide-unique BIFT-id's
> also.
> >
> > If we agree that, we should allow "non-domain-wide-unique" BIFT-id's for
> non-MPLS networks, can we re-phrase the text in
> draft-ietf-bier-non-mpls-bift-encoding-01 to specify that, such an encoding
> option can be used for non-domain-wide-unique cases as well ?
>
> ICE: The 'IBU-SI BIFT Encoding’ is indeed flexible, but with that the
> flexibility is in the way you can add additional future arguments since the
> IBU is like a Label. But, allowing to change the IBU value from hop-by-hop
> like MPLS is adding a lot of complexity and we’re re-inventing MPLS. So
> lets keep this simple and domain side unique.
>
> Thx,
>
> Ice.
>
>
>
> >
> > Thanks,
> > Senthil
> >
> >
> > On Sat, Jan 26, 2019 at 1:43 AM Greg Shepherd <gjshep@gmail.com> wrote:
> >
> > Change of subject. This is WGLC for:
> >
> > https://datatracker.ietf.org/doc/draft-ietf-bier-non-mpls-bift-encoding/
> >
> > Same two week timer.
> >
> > Thanks
> >
> > On Fri, Jan 25, 2019 at 10:13 AM Greg Shepherd <gjshep@gmail.com> wrote:
> > Please read and reply to this thread with your vote for/against adoption
> of:
> >
> > https://datatracker.ietf.org/doc/draft-ietf-bier-non-mpls-bift-encoding/
> >
> > ..as a BIER WG document.
> >
> > This starts a two week counter.
> >
> > Thanks,
> > Chairs
> > (Shep)
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