SCONE

Summary

The SCONE working group held an interim meeting on May 2, 2026, primarily focused on progressing draft-ietf-scone-applicability-manageability toward an early Operations Directorate (OpsDir) review. The group also discussed a new proposal for transport-layer feedback (SCONE-ECHO) and addressed various GitHub issues related to operational considerations, signaling frequency, and tunneling interactions.

Key Discussion Points

Applicability & Manageability Updates

Sanjay Mishra presented updates for draft-ietf-scone-applicability-manageability based on feedback from IETF 125. (Slides: SCONE: Applicability & Management Updates and Applicability & Manageability updates post IETF 125)

Workflow and Merging: Brian Trammell emphasized the goal of merging PRs to produce a clean revision by May 15, 2026, for early OpsDir review. Mirja Kühlewind cautioned against merging PRs where discussion is still active, suggesting that structural changes might still be needed before external review.
Operational Considerations (Issue 21): Zaheduzzaman Sarker expressed concern that documenting specific throughput constraint determination methods (subscriber plans, radio conditions) might be too operator-specific and difficult to generalize. Dan Druta argued that consistent measurement definitions are necessary for "apples-to-apples" comparison between applications and networks.
Signaling and Compliance (Issues 10, 11, 17): The group discussed signaling frequency variations between ABR video and bulk transfers. Updates include clarifying that SCONE advice is stateless and incorporating Mirja Kühlewind's suggestions on using sliding windows for compliance monitoring.
Tunneling and MASQUE (Issue 20): Mirja Kühlewind proposed text regarding MASQUE and UDP tunneling. Christian Huitema and Zaheduzzaman Sarker suggested this might be out of scope for the current document or better addressed in the MASQUE WG. Lucas Pardue suggested capturing that tunneling presents challenges without necessarily providing a full solution in this draft.

SCONE-ECHO (QUIC-Layer Feedback)

Martin Duke presented a proposal for transport-layer feedback of SCONE advice. (Slides: SCONE-ECHO v2)

Concept: A new QUIC frame would echo the 7-bit throughput advice back to the sender at the transport layer. This aims to bypass the need for application-layer APIs (like JavaScript in browsers) to enable faster deployment.
Privacy Concerns: Martin Duke and Lucas Pardue noted potential fingerprinting risks, including the possibility of building "network scanners" to map bandwidth advice across the internet.
Design Trade-offs: Christian Huitema noted that this proposal reverses a previous design decision to keep SCONE at the application layer. Ian Swett suggested SCONE-ECHO could serve as a "stepping stone" for adoption while browser APIs are developed. Mirja Kühlewind warned that transport-layer action without application awareness might not be optimal for all use cases.

Decisions and Action Items

PR Merges: Editors of draft-ietf-scone-applicability-manageability will merge PRs that have reached consensus. Discussions on contested PRs (e.g., Issue 20 on MASQUE and Issue 21 on Operational Considerations) will continue on GitHub/mailing list.
Revision Deadline: A new revision of draft-ietf-scone-applicability-manageability is targeted for mid-May to trigger an early OpsDir review.
SCONE-ECHO: The proposal remains an individual effort for now. Discussion will continue on the mailing list to determine if there is a path toward adoption or if it remains an experimental stepping stone.

Next Steps

Next Interim: A second interim focused on AppMan and operational considerations is being scheduled for June 2026.
IETF 126 (Vienna): The working group plans to have a substantive discussion on SCONE-ECHO, tunneling interactions, and the results of the OpsDir review during the Vienna meeting.
Mailing List: Ongoing discussion regarding the "narrow waist" of QUIC implementations and privacy implications of transport-layer feedback.

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