[mpls] Re: Request WG adoption for draft-jags-mpls-ps-mna-hdr-03.txt

[Rakesh Gandhi <[e-mail]>]

Thanks Loa.

Those are good points. One more reason for carrying IOAM data fields and
IOAM-DEX data fields in PSD!

P.S. We had IOAM as well as IOM-DEX data fields carried in Post-Stack Data
from the very early days of the MPLS IOAM draft due to such issues.

Thanks,
Rakesh



On Wed, Jun 26, 2024 at 4:56 PM Loa Andersson <[e-mail]> wrote:

> Rakesh, Tnx for this, I think we are close with what you say here and
> what I said in my review of draft-mb-mpls-ioam-dex
> [
> https://datatracker.ietf.org/doc/review-mb-mpls-ioam-dex-06-rtgdir-early-andersson-2024-06-17/
> ].
>
> The -dex drafts would fit much nicer if we carried the AD as PSD.
>
> I also have a comment on your bullet 2 below.
>
> 2. IOAM data field format (32-bit) does not fit well into 32-bit ISD
>     LSE due to S bit (e.g., in 31-bit Format D), and it can result in
>     limitations, kind of defeats the use of standard IOAM formats
>
>     There is an additional problem in Format D also the bit zero is
> "taken",
>     it is set to "1", to avoid confusing the it with a bSPL. You only have
>     30 bits available, this does not make it easier.
>
>     And, if you are going to transport a 22-bit sequence number that is by
>     definition mutable,  and can't be transported in bit 1-19. It has to in
>     the 11 bit 10-22 and 24-31. Since it is 22 bits it will take 2 Format D
>     LSEs and make it even more different from the nice 32-bit aligned
> fields
>     in the original dex-draft.
>
>     I think this is a pretty good example of "case 2" in my previous
> mail, it
>     possible to solve as >ISD, but becomes pretty awkward. Points to a PSD
>     based solution.
>
> /Loa
>
> Den 2024-06-26 kl. 21:08, skrev Rakesh Gandhi:
> > Hi Joel,
> >
> > Thanks for your review comment.
> >
> > Based on my understanding, some of the main motivations for adding
> > IOAM direct export data fields in PSD instead of ISD would be:
> >
> >  1. IOAM data fields such as 32-bit Sequence Number or 32-bit
> >     Timestamp in an ISD LSE can lead to undesired ECMP behavior on
> >     nodes that use labels for ECMP hashing
> >  2. IOAM data field format (32-bit) does not fit well into 32-bit ISD
> >     LSE due to S bit (e.g., in 31-bit Format D), and it can result in
> >     limitations, kind of defeats the use of standard IOAM formats
> >  3. IOAM direct export supports extensibility to optionally add
> >     “unlimited” number of data fields. When added as ISD, node RLD
> >     would make it difficult to process the entire label stack
> >  4. IOAM data fields for direct export (e.g., timestamp, sequence
> >     number, flow identifier, Namespace-ID, IOAM Option-Type, etc.)
> >     represent metadata (extra baggage) in the received packets
> >       * NPU simply exports these metadata (extra baggage) and does not
> >         really process them, there is not much motivation to place
> >         them in ISD.
> >
> >
> > Based on the discussion, will update draft-gandhi-mpls-mna-ioam-dex-01
> > <https://datatracker.ietf.org/doc/html/draft-gandhi-mpls-mna-ioam-dex-01>.
>
> >
> >
> > Thanks,
> > Rakesh
> >
> >
> >
> > On Wed, Jun 26, 2024 at 10:06 AM Joel Halpern <[e-mail]>
> wrote:
> >
> >     Rakesh, I tried to understand the explanation in your draft for
> >     why the iOAM DEX needs to be post-stack data.  I could not parse
> >     it.  Could you write an email that explains why you think it is
> >     needed?
> >
> >     Thank you,
> >
> >     Joel
> >
> >     On 6/26/2024 9:12 AM, Rakesh Gandhi wrote:
> >>     Thanks Jags.
> >>
> >>     The PSD solution for MNA defined in draft-jags-mpls-ps-mna-hdr-03
> >>     is used for IOAM and IOAM DEX in draft-gandhi-mpls-mna-ioam-dex-01:
> >>
> >>
> https://datatracker.ietf.org/doc/html/draft-gandhi-mpls-mna-ioam-dex-01
> >>
> >>
> >>     IOAM and IOAM DEX use-cases for MNA are defined in
> >>     draft-ietf-mpls-mna-usecases-10:
> >>
> https://datatracker.ietf.org/doc/html/draft-ietf-mpls-mna-usecases-10
> >>
> >>     The PSD solution is useful for IOAM and IOAM-DEX, I support the
> >>     request for WG adoption for draft-jags-mpls-ps-mna-hdr-03 (as
> >>     co-author).
> >>
> >>     P.S. I understand this email was not the WG adoption poll
> >>     initiated by the chairs.
> >>
> >>     Thanks,
> >>     Rakesh
> >>
> >>
> >>
> >>
> >>
> >>     On Tue, Jun 25, 2024 at 10:52 PM Jaganbabu Rajamanickam
> >>     (jrajaman) <jrajaman=[e-mail]> wrote:
> >>
> >>         Hello Chairs,
> >>
> >>            We would like to request WG adoption for
> >>         draft-jags-mpls-ps-mna-hdr.
> >>
> >>            Updated the draft with the initial review comments and the
> >>         latest MNA header format.
> >>
> >>           Welcome your review comments and suggestions.
> >>
> >>         Thanx,
> >>
> >>         Jags
> >>
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> --
> Loa Andersson
> Senior MPLS Expert
> Bronze Dragon Consulting
> [e-mail]
> [e-mail]
>
>