Hi Bruno,

Thank you for the review.

We have posted rev-07 that addresses your comments.

Please see replies inline with <RG>...


On Wed, Sep 2, 2026 at 10:07 AM <[email protected]> wrote:

> [speaking as individual contributor]
>
>
>
> Hi authors,
>
>
>
> As part of a discussion on the MPLS MNA defined in this draft, I had the
> opportunity to read section 7 again [1]
>
>
>
> Please find below some comments/questions.
>
>
>
>    1. Offset determination
>
> §7.1
>
> “When a Session-Reflector receives a test packet with the MNA Sub-Stack
> with opcode MNA.TSF, it timestamps the test packet payload at a fixed
> offset, pops the MNA Sub-Stack (after completing any other network
> actions), and forwards the test packet as defined in the loopback
> measurement mode for SR-MPLS paths in this document.”
>
>
>
> §7.1.1
>
> “The following properties are locally defined by the operator for this
> opcode.
>
>    - The timestamp format (e.g., 64-bit PTPv2 or NTPv4), to be added to
>    the Session-Sender test packet payload.
>    - The offset in the Session-Sender test packet payload (e.g., STAMP
>    test packet in Figure 5 of [RFC8762
>    <https://www.rfc-editor.org/info/rfc8762>] with an offset of 16 bytes
>    for Receive Timestamp).”
>
>
>
> Since this fixed offset must be determined and configured by the network
> operator, could the document precisely define the starting field and the
> ending field defining this offset (presumably offset:= ending field –
> starting field).
>
> Trying to guess, is this dependent on whether IPv4 or IPv6 is used for the
> test packet? Is this dependent on the number of MPLS labels added for the
> return path?
>
> May be the §14.1 (OPS consideration for TSF) could refer to this and point
> to the relevant specification text.
>

<RG> Added as:

   The TSF opcode enables the Session-Reflector to write the 64-bit
   timestamp in the "Receive Timestamp" field [RFC8972], located at a
   begin offset of 16 bytes from the start of the STAMP test packet
   payload as shown in the Session-Reflector test packet in Figure 2 of
   Section 3 of [RFC8972].



>
>
>    2. MNA.TSF value
>
> “A value for the locally configured MPLS Network Action opcode MNA.TSF,
> called the TSF Network Action, is selected by the operator from the
> "Private Use Range: 115-126" [RFC9994
> <https://www.rfc-editor.org/info/rfc9994>] on the Session-Reflector node.”
>
>
>
> Can you clarify why this specification opted for a Private value, rather
> than a standardized value?
>
> From a network operator standpoint, this represents extra work, for no
> value that I could determine.
>

<RG> Ok, the draft is updated to use standardized values.
<RG> This was also the feedback from the MPLS WG chairs.




>
>
>    3. Configuration
>
> “The Session-Sender needs to know if the Session-Reflector is capable of
> processing the TSF Network Action to avoid dropping the test packets. This
> capability can be locally configured on the Session-Sender or signaled.
> Signaling extensions for this capability exchange are outside the scope of
> this document. »
>
>
>
> My understanding is that the session sender needs to know other
> parameters. E.g., the MAN.TSF value, the offset, the timestamp format
>

<RG> The updated draft removes the configuration steps.

Thanks,
Rakesh (for authors)




>
>
> Thank you,
>
> --Bruno
>
>
>
> [1]
> https://datatracker.ietf.org/doc/html/draft-ietf-spring-stamp-srpm-mpls-06#name-loopback-measurement-mode-w
>
>
>
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