Session Date/Time: 17 May 2022 14:00

LPWAN

Summary

The LPWAN Working Group held an interim meeting to discuss the status of several drafts undergoing shepherding and Working Group Last Call (WGLC) processes. Key discussions revolved around the CHIC YANG data model, the Compound ACK document, and the CHIC over Sigfox specification. The meeting also noted a significant external achievement: the LoRa Alliance's adoption of RFC 9131 (IP over LoRaWAN).

Key Discussion Points

Meeting Logistics & Notewell: The meeting utilized Kodi for collaborative minutes and had a Zulip/Jabber bridge for chat. The IETF Notewell was read, reminding participants of IETF policies, BCPs, and patent disclosure requirements. The meeting was recorded.
YANG Data Model for CHIC (draft-ietf-lpwan-chic-yang):
- Shepherding Review: Pascal Thubert (shepherd) and Dominique Barthel (reviewer) provided feedback to Laurent Toutain (author).
- Resolved Issues: Initial consistency issues (e.g., 0-based vs. 1-based indexing) were addressed.
- Shepherd Comments: Pascal's review identified several items for the author:
  - Add a section on implementations (e.g., partial implementation in OpenCHIC).
  - Ensure YANG doctor is acknowledged (already fixed).
  - Move BCP14 boilerplate text to a dedicated "Requirement Language" section.
  - Address line length issues (over 72 characters) within the YANG module descriptions.
  - Add an informational reference to the foundational YANG RFC (e.g., RFC 7950) when first introducing "YANG."
- Timer Format: A significant discussion focused on representing timers to accommodate both very short (microsecond) and very long (years) durations efficiently.
  - The proposed solution uses tick_duration (2^exponent / 10^6 microseconds) and a 16-bit tick_numbers. An exponent of 20 results in ~1-second ticks, covering typical LoRaWAN timer ranges (e.g., 12 hours). Other exponent values allow for wider ranges. exponent=20 is proposed as the default. This approach was noted as similar to RUPLE's DAO option for units.
- Naming Convention: Debate arose over renaming a position field (to avoid ambiguity) to indensia. Dominique strongly advised against indensia, recommending index or sequence as clearer alternatives for a position within a collection.
Compound ACK (draft-ietf-lpwan-compound-ack):
- Alexander Pelov has taken over as shepherd.
- The ESG recently published a new shepherd write-up template, requiring Alexander to convert the existing write-up.
- Authors are preparing a new version of the draft incorporating Dominique's feedback, new figures, and clarifications on padding bits.
CHIC over Sigfox (draft-ietf-lpwan-chic-sigfox):
- Authors are updating the draft to reorder modes and include a resemblance check sequence.
- WGLC is on hold pending the new version.
- Ana Carolina (shepherd) provided initial feedback:
  - Clarify downlink transmission operation, possibly by referencing RFC8724 Appendix F.
  - Address the implications of dtag=0 (no tag) on packet interleaving. Interleaving without a dtag typically requires using multiple rule IDs, which can increase rule ID space, memory usage, and potentially lead to more bugs or synchronization issues. A 1-bit dtag was suggested as a useful mechanism for interoperability and detecting lost sync.
NBIOT (draft-ietf-lpwan-nbiot-adaptation):
- Sergio Garcia Murillo (author) is preparing to publish the latest version.
- The previous WGLC received minimal reviews. Ana Carolina will serve as shepherd.
IP over LoRaWAN Adoption:
- The LoRa Alliance recently published technical documents adopting RFC 9131 (IPv6 over LoRaWAN), an outcome of significant contributions from this Working Group.
- This is seen as a major achievement, opening new application verticals for IP in LoRaWAN. A LoRa Alliance webinar on the topic is scheduled for June 14th.
OAM Efforts: Dominique Barthel was asked to lead a discussion on the OAM (Operation, Administration, and Maintenance) effort (e.g., ICMP, Ping) at the next interim meeting.

Decisions and Action Items

CHIC YANG Data Model (draft-ietf-lpwan-chic-yang):
- ACTION: Lauren Toutain to publish draft-ietf-lpwan-chic-yang-10 incorporating Dominique Barthel's pull requests, Pascal Thubert's shepherd review comments (implementation section, BCP14 text, line lengths, YANG reference), and a reconsideration of the term indensia (using index or sequence instead).
- ACTION: Pascal Thubert to push for publication of draft-ietf-lpwan-chic-yang-10 once the author's updates are complete.
Compound ACK (draft-ietf-lpwan-compound-ack):
- ACTION: Sergio Garcia Murillo to publish a new version of the Compound ACK draft incorporating Dominique Barthel's feedback, new figures, and clarifications on padding bits.
- ACTION: Dominique Barthel to review the new version of the Compound ACK draft once published.
- ACTION: Alexander Pelov to update the shepherd write-up to the new ESG template after the new version of the draft is stable.
CHIC over Sigfox (draft-ietf-lpwan-chic-sigfox):
- ACTION: Sergio Garcia Murillo to update the CHIC over Sigfox draft, incorporating clarifications on downlink transmission and the dtag/packet interleaving discussion.
- ACTION: Ana Carolina to review the new version of the CHIC over Sigfox draft and commence the shepherd write-up process.
- DECISION: The Working Group Last Call for CHIC over Sigfox is on hold until the new version is published and authors confirm readiness.
NBIOT Adaptation (draft-ietf-lpwan-nbiot-adaptation):
- ACTION: Sergio Garcia Murillo to publish the latest version of the NBIOT draft.
- ACTION: Ana Carolina (shepherd) to solicit additional reviews for the NBIOT draft on the mailing list after the new version is published, given the limited reviews in the previous WGLC.

Next Steps

Document Progress: Authors are expected to publish updated versions of their respective drafts based on the discussions and action items.
Shepherding: Shepherds will continue to guide the drafts through their publication process, including updating write-ups and soliciting reviews.
OAM Discussion: Dominique Barthel will prepare to lead a discussion on the OAM effort (ICMP, Ping, etc.) at the next interim meeting.
Future Work: The WG anticipates moving towards an architecture document, and defining flows for security, configuration provisioning, and data models.
Next Meeting: The next interim meeting is scheduled in two weeks.