[mpls] Re: Working Group Last Call on draft-ietf-mpls-mna-hdr (2nd WG call)

[Greg Mirsky <[e-mail]>]

Dear All,
I've read the latest version of the draft. It is a pleasure to read (thank
authors!) and it provides a practical mechanism that can be used to support
use cases documented in draft-ietf-mpls-mna-usecases
<https://datatracker.ietf.org/doc/draft-ietf-mpls-mna-usecases/>. I support
the publication of the draft.
Below, please find my notes (mostly nits):

   - Abstract
      - Some abbreviations seem unnecessary - OAM, ISD
      - On the other hand, MNA abbreviation is introduced in the first
      sentence. It may be used after that throughout the Abstract.
Alternatively,
      may use the extended form "MPLS Network Action(s)" throughout the Abstract
   - Introduction
      - May use 'AD' after is introduced in the first paragraph. Repeating
      that in the second paragraph is unnecessary.
      - In your opinion, what is the value of "User-defined network actions
      allow new, local actions to be defined."? Note that user-defined actions
      are not discussed anywhere else in the document.
   - Abbreviations
      - Perhaps the expanded form of MNA is singular as 'MPLS Network
      Action', and plural would be MNAs. WDYT?
      - Perhpas a minor modification in capitalization of NAS and
      its varians as "Network Action Sub-stack" (with the capitalized 'Stack'
      should the abbreviation be NASS?)
   - Section 5.2
      - What is the value of the last paragraph:

   If a network action needs to encode more data that might need to

   change during packet forwarding it will need to use a stack of Format

   D LSEs (Section 4.3) (which may be inefficient) or post-stack

   ancillary data (which is beyond the scope of this document).

That paragraph picks only one of scenarios related to AD mutability
(another - changing AD among packets in the same flow). Furthermore,
immutability of 19 LSBs of the Data field in LSE Format D is essential only
in ECMP environment (e.g., DetNet does not use load-balancing) and in the
network in which nodes use the label stack to generate entropy rather than
Entropy Label. I think that the mutability/immutability of AD might be
discussed in documents that describe solutions based on MNA. It seems the
paragraph can me removed without losing any value in the document.


   - Section 7
      - Using the future tense in the two first sentences seems
      unwarranted. PErhaps these can be edited as follows:

OLD TEXT:
   The node adding an NAS to the label stack will need to place a copy
   of the NAS where it can be read by the relevant nodes.  Each
   downstream node along the path will have a Readable Label Depth (RLD)
   [I-D.ietf-mpls-mna-fwk].
NEW TEXT:
   The node adding an NAS to the label stack places a copy
   of the NAS where the relevant nodes can read it.  Each
   downstream node along the path has a Readable Label Depth (RLD)
   [I-D.ietf-mpls-mna-fwk].


   - Section 9.2
      - The mutability of 20 LSBs considered only from the PoV of the
      packet traversing the MPLS network. As noted above, to avoid out-of-order
      delivery for the same MPLS flow, 20 LSBs must be immutable among
packets in
      the same MPLS data flow.
   - Section 15
      - The firsrt field in Figure 7 is tagged differently "MNA-Label=bSPL
      (TBA)" from Figures 5, 6, 8, 9, and 10. Personally, I like Figure 7-style
      better.

Regards,
Greg

On Tue, Sep 24, 2024 at 6:25 AM Tarek Saad <[e-mail]> wrote:

> Dear WG,
>
>
>
> This email starts a two-week Working Group last call for
> draft-ietf-mpls-mna-hdr
> <https://datatracker.ietf.org/doc/draft-ietf-mpls-mna-hdr/>. This is the 2
> nd WG last call for this document.
>
> Please indicate your support or concern for this draft. If you are opposed
> to the progression of the draft to RFC, please articulate your concern. If
> you support it, please indicate that you have read the latest version, and
> it is ready for publication in your opinion. As always, review comments and
> nits are most welcome.
>
>
>
> Please send your comments to the mpls WG mailing list ([e-mail])
>
> If necessary, comments may be sent unidirectional to the WG chairs.
>
>
>
> Note, currently there are 5 IPR disclosures against this document at
> https://datatracker.ietf.org/ipr/search/?submit=draft&id=draft-ietf-mpls-mna-hdr
>
>
>
> This poll runs until October 8, 2024.
>
>
>
> Thank you,
>
> Tarek (for the MPLS WG co-chairs)
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