Re: [mpls] WG last call: draft-ietf-mpls-inband-pm-encapsulation

Hi, Tony and All,
I've read the latest version of the draft. Please find my comments below:

   - The proposed mechanism, as stated in Abstract, applies to "MPLS live
   traffic". I couldn't find the definition of the term "live traffic" and
   appreciate it if you can clarify it for me. Does that apply to any MPLS
   packet or a particular class of MPLS packets in a network?
   - I appreciate that the document mentions work on Synonymous Flow
   Labels. However, it is not clear to me why SFL-based application of the AMM
   is characterized as hop-by-hop, while the solution described in the draft -
   as edge-to-edge. I would appreciate it if the authors can clarify that
   characterization of measurement methods, particularly since the T-bit
   (defined in Figure 1) differentiates between edge-to-edge and hop-by-hop
   measurements using the proposed solution.
   - Furthermore, it seems like the comparison of the impact on an MPLS
   packet of the proposed solution and IOAM is inaccurate. As I understand it,
   contrary to the statement in Introduction that "the former doesn't
   introduce any new header whereas the latter introduces a new In-situ OAM
   header", both introduce (unlike SFL-based application of AMM) extra
   ancillary data in an MPLS packet.
   - And, on the last paragraph in Introduction. I believe that publishing
   a draft on Standard track and then moving it to Historic once another
   solution is standardized by IETF is sub-optimal. I recognize the value of
   the work put in by implementers of the described in the draft solution. The
   deployment experience is invaluable. On the other hand, there seems to be
   an agreement that the MNA is the preferred mechanism to support AMM in the
   MPLS networks. (Note that draft-ietf-mpls-mna-usecases is being updated to
   include AMM as another use cases of on-path telemetry in the MPLS networks,
   in addition of IOAM). Hence my proposal to switch this document to
   Experimental track (see my question about the requested IANA allocation
   below).
   - The list of implementations is impressive and suggests that there are
   several deployments. If that is the case, which value of eSPL for Flow-ID
   Label Indicator is used?

In conclusion, I don't support progressing this draft on the Standard
track. I would support progressing it as Experimental or Informational
(perhaps that means that the IANA section is removed).

Regards,
Greg

On Thu, Apr 25, 2024 at 8:09 AM Tony Li <tony.li@tony.li> wrote:

>
> [WG chair hat: on]
>
>
> Hi all,
>
> This starts a 2 week working group last call on
> draft-ietf-mpls-inband-pm-encapsulation.
>
> This last call ends at 12:01 PM PDT, Thurs. May 9, 2024.
>
> Please send all comments to the mailing list.
>
> Regards,
> Tony
>
>
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