SCHC

Summary

The SCHC Working Group held an interim meeting to review document status, receive a technical presentation on ARC FEC (Forward Error Correction) mode using XOR streaming, announce leadership changes, and discuss the progress of the SCHC Architecture Design Team.

A significant leadership transition was announced by Area Director Éric Vyncke: Marion Dumay is appointed as the new WG Co-Chair, and Quentin Lampin is appointed as a Technical Advisor. Pascal Thubert will step down around IETF 126 in Vienna.

Key Discussion Points

1. Administration and Document Status

Alexander Pelov presented the Chair Slides and gave a status update on active WG documents:

draft-ietf-schc-over-networks-prone-to-disruptions: The WG is waiting for an updated version of the draft before initiating a Working Group Adoption Call.
draft-ietf-schc-protocol-numbers: A shepherd has been assigned.
draft-ietf-schc-8824-update: Alexander Pelov is shepherding this document. The review has begun, and feedback will be provided in June, ahead of IETF 126. Marco Tiloca was asked to upload a new version to keep the draft active.
Expired Documents: The chairs will reach out to the authors of expired WG documents to clarify their intentions (e.g., preparing for WG Last Call).

2. ARC FEC Mode and XOR Streaming Performance

Javier FERNANDEZ presented a proof-of-concept (PoC) implementation and performance analysis for ARC FEC Mode (an individual draft proposing a new FEC-based fragmentation mode).

Technical Details:
- The mechanism uses two different encoding geometries (matrix or buffer). The buffer geometry enables simpler algorithms like XOR.
- The PoC features a highly memory-efficient implementation of the stream encoder, fragmenter, decoder, and reassembler without duplicate buffers.
- Uses a 2-out-of-3 XOR parity scheme combined with a simple interleaving pattern to provide robustness against burst errors.
Simulation Results:
- Tested across link loss probabilities ranging from 10% to 50%.
- Even under high loss scenarios (e.g., 50% link loss), the combined FEC and ARQ mechanism achieved an approximate 80% success rate.
- Alexander Pelov noted that the simulation metrics clearly demonstrated FEC successfully recovering the majority of packages without needing ARQ retransmissions.
- Javier FERNANDEZ will share the repository link with the group and provide more detailed slides at the next meeting.

3. WG Leadership Updates

Area Director Éric Vyncke joined the session to announce changes in the SCHC Working Group leadership:

Marion Dumay has been selected as the third WG Co-Chair.
Quentin Lampin has been appointed as a WG Technical Advisor to provide technical guidance without formal chair duties.
Pascal Thubert will step down from the Co-Chair role around IETF 126 in Vienna as he transitions into retirement.

4. SCHC Architecture Advancement

The group reviewed the status of the SCHC Architecture Work, referring to the SCHC Architecture Advancement (reminder) slides.

Quentin Lampin summarized the core architectural definitions (endpoints, instances, contexts, domains, sessions) established by the Design Team.
Open Issue: Multiplexing multiple sessions over the same link (the encapsulation/multiplexing/transport placeholder). The Design Team is currently cataloging existing IETF protocols that could address this.
Alexander Pelov and Quentin Lampin invited interested participants to join the open Design Team.

5. IETF 126 Planning

A 1.5-hour slot has been requested for IETF 126.
Efforts will be made to avoid scheduling conflicts for key contributors, specifically Carsten Bormann and Marco Tiloca.

Decisions and Action Items

Leadership Appointment: Marion Dumay officially joins as WG Co-Chair; Quentin Lampin joins as Technical Advisor.
Action Item (Chairs): Contact authors of expired working group drafts to determine next steps.
Action Item (Design Team): Publish an updated version of the SCHC Architecture draft within the next two weeks.
Action Item (Marco Tiloca): Submit an updated version of draft-ietf-schc-8824-update to keep the document alive.

Next Steps

The next interim meeting will be scheduled in two weeks.
Javier FERNANDEZ will present detailed performance slides on the ARC FEC PoC.

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