Session Date/Time: 22 Feb 2022 15:00

LPWAN

Summary

The LPWAN working group intermeeting covered administrative updates, document status, and planning for IETF 113. Key technical discussions included the finalization of the NBIoT document, which is now ready for deep review, and a significant discussion on the challenges of applying dev and app roles in CHIC for IEEE 802.15.4 mesh and peer-to-peer topologies. Actions were set for document reviews, publications, and further discussion on the dev/app role issue.

Key Discussion Points

Administrative Items:
- Chairs reminded participants of the IETF Notwell, IPR policy, anti-harassment policy, and the process for contributing to meeting minutes and automatic attendance capture.
- The agenda for the intermeeting was reviewed, covering IETF 113 planning, NBIoT document progress, CHIC compression over 15.4, Data Model updates, and Compound ACK review.
- Previous action items were reviewed, including the OAM document's readiness for a call for adoption and the status of the Data Model draft.
Document Status Updates:
- Laurent reported that a new version of the CHIC YANG data model has been published to GitHub, compliant with RFC formatting. He aims to upload it to the data tracker soon, potentially enabling a Working Group Last Call before IETF 113.
- Laurent confirmed plans for a hackathon at IETF 113 focused on CHIC and the data model.
- The OAM document's milestone was updated to end of 2022. The Sigfox document, previously blocked by Compound ACK progress, is expected to move towards Last Call soon.
- Two new document publications were noted: a new version of the NBIoT document and version 3 of the Compound ACK document (incorporating suggested text edits). A new version of the OAM document by Dominic has also been published.
IETF 113 Planning:
- A reminder was issued about time zone differences between the US (Daylight Saving Time) and Europe (UTC+1) around IETF 113.
- Laurent volunteered to physically attend IETF 113 and sit in the chair's seat during the LPWAN session, as other chairs anticipate remote attendance.
- The working group has requested a one-hour slot for IETF 113. A call for presentations, with slots typically 10-15 minutes maximum, will be sent out shortly.
NBIoT Document Progress (Anna):
- Anna presented the latest progress on the NBIoT document, confirming that modifications related to CHIC fragmentation and compression over NBIoT networks are complete.
- The "delay tolerant problem" aspect, previously considered for this document, will now be addressed in a separate, new document.
- A key technical update in version 7 is the introduction of a variable-size Rule ID space for both compression and fragmentation.
- The document is considered ready for Last Call, pending a deep technical review. Carles volunteered for this review.
CHIC dev and app Roles in 15.4 Mesh (Carles):
- Carles presented a discussion topic on applying the dev (constrained device) and app (application server) roles, defined in RFC8376 and RFC8724, to CHIC header compression in IEEE 802.15.4 mesh topologies and peer-to-peer (P2P) scenarios.
- In traditional star topologies, dev and app roles enable a single CHIC rule to function for both uplink and downlink directions. However, in mesh or P2P scenarios, where devices might have symmetrical interactions, assigning fixed dev or app roles to individual nodes becomes challenging.
- Discussion explored two main approaches for P2P:
  1. Dynamic Role Assignment: The sender in a given frame or flow is dynamically assigned the dev role, and the receiver the app role. This might necessitate a bit or flag in the header to indicate direction, or context within the rule.
  2. Pre-negotiated/Configured Roles: For each specific P2P relationship, dev and app roles are agreed upon or configured (e.g., using a tie-breaker like smallest MAC address) prior to CHIC operation.
- It was noted that introducing a new bit for direction would impact the data model and potentially require a new standard track document.
- The scope of rules (whether common across a mesh or specific to an association between two devices) was also highlighted as a factor influencing the solution.

Decisions and Action Items

DECISION: The "delay tolerant problem" initially discussed for the NBIoT document will be addressed in a separate, new document.
DECISION: The new version of the OAM document by Dominic, published online, is ready for a call for adoption.
ACTION ITEM: Carles to perform a deep technical review of the NBIoT document by IETF 113. Ideally, comments should be submitted before the session to allow authors to review them.
ACTION ITEM: Laurent to publish the new version of the CHIC YANG data model to the IETF data tracker this week or early next week, to enable a potential Working Group Last Call before IETF 113.
ACTION ITEM: Laurent to add a CHIC/data model hackathon item to the IETF 113 calendar.
ACTION ITEM: Carles to send an email to the LPWAN mailing list summarizing the two proposed solutions for handling dev/app roles in peer-to-peer CHIC scenarios (dynamic assignment vs. pre-negotiated/configured roles), including examples, to facilitate further discussion.
ACTION ITEM: Chairs to send out a call for presentations for the LPWAN session at IETF 113.

Next Steps

Continue the discussion on the dev and app roles for CHIC in IEEE 802.15.4 mesh and peer-to-peer scenarios on the mailing list, with a dedicated slot for this topic planned for IETF 113.
Address review comments for the NBIoT document during the IETF 113 session, with the aim of proceeding to Working Group Last Call shortly thereafter.
Conduct the planned hackathon at IETF 113 on CHIC and the data model.
Prepare and submit presentation requests for the LPWAN session at IETF 113.