SCHC

Session: SCHC Interim Meeting (interim-2026-schc-09)
Date: 2026
Chairs: Alexander Pelov
Attendees: Marion Dumay, Quentin Lampin, Marco Tiloca, Alexander Pelov

Summary

The SCHC Working Group held an interim meeting to discuss the current status of its active work program and to review a technical proposal for a minimal multiplexer for SCHC ("VOICI").

The chairs reviewed the progress of active working group drafts, noting milestones and coordinating actions with related working groups (such as IPSECME). A technical presentation was delivered on VOICI, detailing its architecture, design goals, and potential integration into the SCHC framework for highly constrained LPWAN environments.

Key Discussion Points

1. Administration & Agenda Bashing

Presenter: Alexander Pelov
Slides: Chair Slides
Discussion:
- Alexander Pelov welcomed the participants, presented the IETF Note Well, and reviewed the agenda. The agenda was accepted as presented.

2. Working Group Document Status

Discussion:
- draft-ietf-schc-8824-update: The group noted that this document is progressing well. It continues to address refinements to CoAP header compression static context.
- draft-ietf-schc-protocol-numbers: Discussions centered on completing registry coordination and finalizing the assignment mechanisms.
- draft-ietf-schc-over-networks-prone-to-disruptions: The authors continue to refine fragmentation behavior under unstable link conditions.
- draft-ietf-schc-schclet: Noted as a key document for modular implementations of the SCHC framework.
- draft-ietf-ipsecme-diet-esp: Briefly discussed coordination with the IPSECME working group regarding the compression of ESP headers.

3. VOICI: A Minimal Multiplexer for SCHC

Presenter: Quentin Lampin
Slides: VOICI a minimal Multiplexer for SCHC
Discussion:
- Quentin Lampin presented "VOICI", a proposal for a lightweight, minimal multiplexing layer for SCHC. In many constrained environments, there is a need to support multiple SCHC instances or multiplex different protocol flows over a single physical or link-layer channel without introducing significant overhead.
- Quentin Lampin detailed how VOICI achieves multiplexing with minimal byte overhead (often less than a single byte) by leveraging existing identifiers or utilizing small, prepended tags.
- Alexander Pelov queried how the Rule ID namespace is managed within VOICI, specifically asking whether VOICI partitions the Rule ID space or acts as a clean encapsulating layer above the lower layer.
- Quentin Lampin clarified that VOICI is designed to be flexible; it can either manage partitioned Rule IDs or prepend a minimal header, depending on the constraints of the specific underlying LPWAN technology.
- Marion Dumay shared feedback on early prototyping efforts, noting that the minimal overhead of VOICI is highly beneficial for bandwidth-constrained technologies like LoRaWAN or Sigfox, where every byte saved directly impacts device battery life and network capacity.
- Marco Tiloca raised a question regarding the security model of VOICI, particularly when multiplexed flows have varying security requirements (such as OSCORE versus DTLS or Diet-ESP). He suggested analyzing how draft-ietf-ipsecme-diet-esp interacts with the multiplexer to ensure that security associations are not misaligned or bypassed.
- Quentin Lampin responded that VOICI is cryptographically agnostic and serves strictly as a layer-2.5 routing/multiplexing mechanism, but agreed that clarifying the interaction with security protocols is an important next step.

Decisions and Action Items

Action Item: Quentin Lampin and Marion Dumay to continue refining the VOICI proposal, incorporating feedback on Rule ID management and security considerations, and prepare to document this work in an upcoming Internet-Draft.
Action Item: Active contributors to review draft-ietf-schc-8824-update and draft-ietf-schc-protocol-numbers ahead of the next session to clear outstanding issues.

Next Steps

Continue discussion on the mailing list regarding VOICI implementation experiences and its potential adoption path within the working group.
Maintain ongoing coordination with IPSECME on draft-ietf-ipsecme-diet-esp.

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