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

[Joel Halpern <[e-mail]>]

Maybe I am naive, but it seemed to me that the restructuring of the 
information between the ISD representation and the DEX export 
representation was not a big deal.

And the RLD seems to be a significant problem for both answers.

Yours,

Joel

On 6/26/2024 5:26 PM, Rakesh Gandhi wrote:
> 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]
>