[spring] Re: [mpls] WG Last Call: draft-ietf-spring-stamp-srpm-mpls-12 (Ends 2026-11-04)

[Greg Mirsky <[e-mail]>]

Dear Authors, et al.
Thank you for your work on this specification. Please find my notes on the
draft below. As the draft, as I believe, defines new performance metrics, I
invite the BPM WG and the Performance Directorate to the discussion.
My main concern is about the relationship between the "loopback round-trip
delay" measurement method defined in the draft and the round-trip delay
performance metric (RTDelay) and its measurement method, as defined in RFC
2681 <https://www.rfc-editor.org/info/rfc2681/>, and referenced in the IANA
Performance Metrics registry
<https://www.iana.org/assignments/performance-metrics>.

My reading of the draft is that loopback round-trip delay, while
operationally similar to RTT, is not obviously identical to the RFC 2681
Type-P-Round-trip-Delay metric.

If the draft intends to claim conformance with RFC 2681/IANA RTDelay
metrics, it should probably:

   - explicitly justify the equivalence, or
   - define the loopback result as a new metric, derived from but distinct
   from RFC 2681 RTDelay.

A minor note. The draft references a two-way delay metric, while no such
metric is listed in the IANA Performance Metrics registry.

Regards,
Greg

On Fri, Oct 16, 2026 at 12:53 PM Alvaro Retana via Datatracker <
[e-mail]> wrote:

> This message starts a WG Last Call for:
> draft-ietf-spring-stamp-srpm-mpls-12
>
> This Working Group Last Call ends on 2026-11-04
>
> Abstract:
>    Segment Routing (SR) can be used to steer packets through a network
>    employing source routing.  SR can be applied to both MPLS (SR-MPLS)
>    and IPv6 (SRv6) data planes.  This document specifies procedures for
>    performance measurement in SR-MPLS networks using the Simple Two-Way
>    Active Measurement Protocol (STAMP), as specified in RFC 8762, along
>    with its optional extensions specified in RFC 8972 and the SR-
>    specific extensions specified in RFC 9503.  These procedures measure
>    SR-MPLS paths, including Segment Lists of SR-MPLS Policies, SR-MPLS
>    IGP best paths, and SR-MPLS IGP Flexible Algorithm (Flex-Algo) paths,
>    as well as Layer-3 and Layer-2 services carried over those paths.
>
> File can be retrieved from:
> https://www.ietf.org/archive/id/draft-ietf-spring-stamp-srpm-mpls-12.txt
>
> Please review and indicate your support or objection to proceed with the
> publication of this document by replying to this email keeping
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> resolve them are highly appreciated.
>
> This document requires in-depth technical reviews to move forward.
>
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> Appropriate IPR disclosures required for full conformance with the
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> of BCP 78 [1] and BCP 79 [2] must be filed, if you are aware of any.
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>
> Thank you.
>
> [1] https://datatracker.ietf.org/doc/bcp78/
> [2] https://datatracker.ietf.org/doc/bcp79/
> [3] https://datatracker.ietf.org/doc/rfc6701/
>
> The IETF datatracker status page for this Internet-Draft is:
> https://datatracker.ietf.org/doc/draft-ietf-spring-stamp-srpm-mpls/
>
> There is also an HTML version available at:
> https://www.ietf.org/archive/id/draft-ietf-spring-stamp-srpm-mpls-12.html
>
> A diff from the previous version is available at:
>
> https://author-tools.ietf.org/iddiff?url2=draft-ietf-spring-stamp-srpm-mpls-12
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