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

[Liaison Statement Management Tool <[e-mail]>]

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