[Detnet] Re: New Liaison Statement, "LS on deterministic networking work of draft Recommendation ITU-T Y.qos-sre-rf in Q6/WP4 of ITU-T SG13"

[Jinoo Joung <[e-mail]>]

Hello Scott and WG,
thanks for the valuable information regarding a liaison.
Now I have a better understanding how a liaison may be stated.

I also agree with the texts provided in the last part. I think It is
concise and clear.

Best regards,
Jinoo

On Thu, Sep 17, 2026 at 5:44 PM Scott Mansfield <
[e-mail]> wrote:

> A liaison from the IETF to SG13 may provide information on changes made to
> an IETF Internet-Draft and may, if appropriate, identify the SG13 documents
> that could be affected by those changes. The liaison may also indicate
> which SG13 documents informed or motivated the changes incorporated into
> the Internet-Draft.
>
>
>
> Because both the IETF and ITU-T operate through contribution-driven
> processes, it would not be appropriate for the IETF to use a liaison
> statement to direct or prescribe modifications to an ITU-T Recommendation
> based on changes made elsewhere. A liaison may identify a potential
> inconsistency or highlight an issue for consideration, but any resulting
> modifications to ITU-T texts would need to be proposed and advanced through
> contributions submitted by ITU-T members in accordance with ITU-T
> procedures.
>
>
>
> Based on the notes below I think what the IETF could say is: (If I
> understand the nuance of Jinoo’s points)…
>
>
>
> The IETF DETNET Working Group is aware of the work in ITU-T Y.qos-sre-rf.
> In support of maintaining consistency between IETF and ITU-T
> specifications, draft-ietf-detnet-stateless-fair-queuing relies on concepts
> defined in ITU-T Recommendations Y.3129 and Y.3148. The IETF would welcome
> information on any significant updates to Y.3129 and Y.3148 as work on
> those Recommendations progresses.
>
>
>
> -scott.
>
>
>
> *From:* Jinoo Joung <[e-mail]>
> *Sent:* Wednesday, September 16, 2026 9:26 PM
> *To:* Mike Blanche <[e-mail]>
> *Cc:* Deterministic Networking Discussion List <[e-mail]>; Janos
> Farkas <[e-mail]>; Lou Berger <[e-mail]>
> *Subject:* [Detnet] Re: New Liaison Statement, "LS on deterministic
> networking work of draft Recommendation ITU-T Y.qos-sre-rf in Q6/WP4 of
> ITU-T SG13"
>
>
>
> Dear Chairs, Mike, and WG,
>
>
>
> As it was discussed during the meeting and the offline chat after the
> meeting,
>
> the standards produced in both SDOs should remain consistent and
> non-overlapping.
>
> This is what we have agreed upon.
>
>
>
> I think it would be helpful to send a liaison to ITU-T SG13 to suggest
> that;
>
> - ITU-T Y.3129 and Y.3148 should be revised accordingly to reflect the
> addition of the medata that is being suggested by ITU-T Y.qos-sre-rf.
>
> - draft-ietf-detnet-stateless-fair-queuing should develop the MPLS and
> IPv6 header format in-line with the framework specified by Y.3129 and
> Y.3148.
>
>
>
> Best regards,
>
> Jinoo
>
>
>
>
>
>
>
> On Thu, Aug 6, 2026 at 8:58 PM Mike Blanche <[e-mail]> wrote:
>
> (trimming to the detnet wg)
>
>
>
> Hello Detnet WG, chairs,
>
>
>
> Catching up after Vienna - thank you for sharing this liaison from ITU-T
> SG13.
>
>
>
> From Jinoo's presentation
> <https://datatracker.ietf.org/meeting/126/materials/slides-126-detnet-03-latency-guarantee-with-stateless-fair-queuing-00>
> at IETF 126, I think the proposed solution to the issue identified in this
> liaison is to amend draft-ietf-detnet-stateless-fair-queuing so it uses
> four metadata fields instead of three. This then creates a challenge back
> in ITU-T SG13 because Y.3129 and Y.3148 refer to three metadata fields not
> four.
>
>
>
> Jinoo's presentation says these ITU-T standards will now be revised, but I
> suggest mentioning this in the return liaison, as changing the IETF draft
> triggers a need for such revisions to maintain consistency.
>
>
>
> It was great that the Q6/13 rapporteur could attend the detnet session in
> Vienna and meet with the chairs afterward. I encourage a continued
> conversation between the chairs and the two groups more broadly, as
> suggested in the liaison.
>
>
>
> If the chairs would like specific suggested wording for the liaison
> response, please let me know.
>
>
>
>
>
>
>
> Beyond the specific response to this liaison, I remain concerned that some
> of this work is still evolving, making standardisation potentially
> premature. The ongoing discussion about encoding the required
> metadata illustrates this point:
>
>
>
> 1) Y.3129 ("Requirements and framework for stateless fair queueing") was
> consented in April 2024 with 3 metadata fields.
>
> 2) Y.3148 ("Functional architecture for stateless fair queuing in large
> scale networks including IMT-2020 and beyond") initially included only 2
> metadata fields, described as an optimisation. When it was being finalised
> in April 2025, following discussion, this was then changed to 3 fields to
> be consistent with Y.3129 and consented as such.
>
> 3) when adopting draft-joung-detnet-stateless-fair-queuing in March 2026,
> the unadopted I-D also used 2 pieces of metadata, and we discussed making
> it consistent with the two published ITU-T standards above. The initial
> proposal on the mailing list (here
> <https://mailarchive.ietf.org/arch/msg/detnet/Z6kwG_bScD8TrUMunulcVDwHyTs/>)
> was for the draft to support 2 or 3 pieces of metadata. After IETF 125 and
> further discussion, the draft was adopted using 3 metadata fields.
>
> 4) Back in SG13, a further related draft standard Y.qos-sre-rf is coming
> up for consent, but it has 4 pieces of metadata, generating this liaison.
>
> 5) The proposal made at IETF 126 is to
> modify draft-ietf-detnet-stateless-fair-queuing, Y.3129 and Y.3148 to use 4
> pieces of metadata. I understand this is the final proposed revision!
>
>
>
> The resulting need for ongoing amendment of drafts and published standards
> across multiple SDOs seems inefficient. I hope we have settled on a
> consistent, forward-looking set of metadata necessary to implement these
> algorithms (and any future related work) without further changes to
> existing standards.
>
>
>
> Feedback from implementers using these architectures in the wild would be
> very useful input.
>
>
>
> Many thanks,
>
>
>
> Mike
>
>
>
> On Tue, 21 Jul 2026 at 07:13, Liaison Statement Management Tool <
> [e-mail]> wrote:
>
> Title: LS on deterministic networking work of draft Recommendation ITU-T
> Y.qos-sre-rf in Q6/WP4 of ITU-T SG13
> Submission Date: 2026-07-20
> URL of the IETF Web page: https://datatracker.ietf.org/liaison/2204/
>
> To: Deterministic Networking (detnet)
> From: ITU-T SG 13
> Purpose: For action
> Please reply by 2026-09-30
>
> Email Addresses
> ---------------
> From: [e-mail]
> To: Lou Berger <[e-mail]>,János Farkas <[e-mail]>
> Cc: Jim Guichard <[e-mail]>,Deterministic
> Networking Discussion List <[e-mail]>,Lou Berger <[e-mail]>,Scott
> Mansfield <[e-mail]>,Ketan Talaulikar <
> [e-mail]>,János Farkas <[e-mail]>,Gunter
> Van de Velde <[e-mail]>
> Response Contacts: [e-mail]
> [e-mail]
> Technical Contacts: [e-mail]
>
>
> Body: 1. Purpose
>
> The purpose of this liaison statement is to inform the IETF DetNet Working
> Group about the maturity of draft Recommendation ITU-T Y.qos-sre-rf, which
> is currently being prepared for consent in SG13 for our October 2026
> Plenary meeting, and to seek feedback to ensure alignment with ongoing IETF
> draft standards.
>
> 2. Discussion and Context
>
> ITU-T Q6/13 has been progressing work on deterministic networking and
> stateless mechanisms. Recommendation ITU-T Y.3129 "Requirements and
> framework for stateless fair queuing in large scale networks including
> IMT-2020 and beyond", utilises three pieces of metadata carried within
> packet headers to execute stateless fair queuing in core nodes:
>
> a) The packet's Finish Time
> b) The flow's allocated service rate
> c) The maximum packet size of the flow
>
> We acknowledge and highly value the parallel work occurring within the
> IETF DetNet WG,  in particular via
> draft-ietf-detnet-stateless-fair-queuing, which specifies the mechanisms to
> encapsulate these three fields into IPv6 and MPLS.
>
> 3. Y.qos-sre-rf Fourth Metadata Field
>
> The new draft Recommendation ITU-T Y.qos-sre-rf extends this capability
> into the control plane for stateless admission control. To identify the
> total service rates of active flows on a link without maintaining per-flow
> state tables, the framework introduces a fourth metadata field:
>
> d) Finish Time Difference: Defined as the difference between the current
> packet’s finish time and the previous packet’s finish time
>
> Because this remains constant across all nodes in the path, core nodes can
> use it alongside the existing Y.3129 metadata to determine whether an
> arriving packet "encompasses" a given estimation reference time. This
> allows the node to mathematically infer active flow rates during an
> inspection interval without managing flow states.
>
> 4. Request for Feedback
>
> As the IETF DetNet WG is actively developing the IPv6 and MPLS
> encapsulation for stateless fair queuing, Q6/13 respectfully requests that
> the IETF DetNet WG review this draft new Recommendation and provide
> feedback from an IETF perspective, particularly regarding its relationship
> with draft-ietf-detnet-stateless-fair-queuing.
>
> We would highly appreciate your response before our next SG13 Plenary
> meeting, scheduled for October 2026.
>
> 5. Future Collaboration
>
> More broadly, Q6/13 recognizes that closer collaboration between our
> organisations would benefit the development of deterministic networking. We
> welcome the opportunity for enhanced collaboration, including the potential
> for joint or co-located meetings in future cycles. In addition to this
> Liaison, the Rapporteur of Q6/13 will reach out informally to the IETF
> DetNet WG Chairs to discuss potential areas for cooperation.
> Attachments:
>
>     Draft Recommendation ITU-T Y.qos-sre-rf: “Requirements and framework
> for service rates estimation with packet metadata for stateless admission
> control”
>
> https://www.ietf.org/lib/dt/documents/LIAISON/liaison-2026-07-21-itu-t-sg-13-detnet-ls-on-deterministic-networking-work-of-draft-recommendation-itu-t-yqos-sre-rf-in-q6wp4-of-itu-t-sg13-attachment-1.pdf
>
>
> _______________________________________________
> detnet mailing list -- [e-mail]
> To unsubscribe send an email to [e-mail]
>
> _______________________________________________
> detnet mailing list -- [e-mail]
> To unsubscribe send an email to [e-mail]
>
>