**Session Date/Time:** 09 Jun 2026 14:00 # [SCHC](../wg/schc.html) **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](https://datatracker.ietf.org/meeting/interim-2026-schc-09/materials/slides-interim-2026-schc-09-sessa-chair-slides-00) * **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](https://datatracker.ietf.org/doc/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](https://datatracker.ietf.org/doc/draft-ietf-schc-protocol-numbers/)**: Discussions centered on completing registry coordination and finalizing the assignment mechanisms. * **[draft-ietf-schc-over-networks-prone-to-disruptions](https://datatracker.ietf.org/doc/draft-ietf-schc-over-networks-prone-to-disruptions/)**: The authors continue to refine fragmentation behavior under unstable link conditions. * **[draft-ietf-schc-schclet](https://datatracker.ietf.org/doc/draft-ietf-schc-schclet/)**: Noted as a key document for modular implementations of the SCHC framework. * **[draft-ietf-ipsecme-diet-esp](https://datatracker.ietf.org/doc/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](https://datatracker.ietf.org/meeting/interim-2026-schc-09/materials/slides-interim-2026-schc-09-sessa-voici-a-minimal-multiplexer-for-schc-01) * **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](https://datatracker.ietf.org/doc/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](https://datatracker.ietf.org/doc/draft-ietf-schc-8824-update/) and [draft-ietf-schc-protocol-numbers](https://datatracker.ietf.org/doc/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](https://datatracker.ietf.org/doc/draft-ietf-ipsecme-diet-esp/).