Session Date/Time: 17 Sep 2024 15:00

NTP

Summary

This interim meeting of the NTP Working Group provided updates on the status of various drafts nearing publication, discussed ongoing coordination with IEEE 1588, and focused on the progress of NTPv5 and Roughtime. Key topics included addressing outstanding comments on the NTP Requirements draft, planning a hackathon for NTPv5 and Roughtime implementations at IETF 118 Dublin, and a discussion on integrating "grease" mechanisms into NTPv5 and NTS to improve protocol evolution and resilience. An implementation issue related to NTS key exporters was also briefly discussed, with further conversation directed to the mailing list.

Key Discussion Points

Document Status Update:
- NTP Update Registries: Issues from IESG review resolved; document is now with the AD for further progression.
- Enterprise Profile: Completed IETF Working Group Last Call and is currently in negotiations with the ADs.
- NTP over PTP: Working Group consensus has been reached to move the document forward; a shepherd write-up is pending. Coordination with the IEEE 1588 community is complete.
- NTP Interleave Modes: The document has been updated and is progressing.
IEEE 1588 Activities:
- IEEE 1588.1 Revision (Client-Server PTP): A new revision has been approved, focusing on a client-server PTP model similar to NTP. Work has begun, with potential for reusing NTP over PTP and NTS concepts. Early stages, with multiple proposals on the table.
- Joint Security Meeting: An informal joint meeting with the 1588 security community is planned for late September/early October. The PTP community is examining vulnerabilities identified by the NTP community related to NTS. Increased coordination between the groups is a goal.
NTP Requirements Draft:
- The document has stalled and is currently expired.
- A desire was expressed to move it forward and address remaining comments.
- The Working Group will aim to move this document to the NTP GitHub organization.
- A sense of those present indicated that most critical comments have been addressed, with remaining issues being minor details or language.
NTPv5 Specification:
- Discussion on moving the "unsynchronized status" as suggested by a participant, which may lead to different interpretations between NTPv4 and NTPv5 clients but could result in a cleaner design.
- The unresolved issue of reference clock identification (new field vs. encoding in bloom filter) was noted.
- Interoperability testing between existing implementations appears to be working, with minor issues resolved.
- A hackathon for NTPv5 is planned for IETF 118 in Dublin in November to encourage further implementations and feedback.
Roughtime:
- The Roughtime repository has been successfully moved to the IETF NTP Working Group GitHub organization.
- A significant text revision is pending submission as a Pull Request.
- A work meeting identified and ironed out most outstanding issues.
- Marcus noted finding 9 Roughtime implementations, with 5-6 actively maintained. Netnod has received funding to work on Roughtime.
- A hackathon for Roughtime is planned for IETF 118 in Dublin, with Marcus intending to join. Efforts will be made to invite other implementers.
- Discussion on extending the "grease" section and clarifying intentionally malformed Roughtime messages to test client resilience. This is not expected to be contentious.
NTS Implementation Issue (NTP):
- An issue was raised regarding an incorrect exporter used for NTS keys in current client/server implementations.
- The Working Group briefly discussed potential involvement in fixing this, possibly via a document update if no other implementations use the affected algorithm.
- The discussion was directed to continue on the mailing list for broader input.
NTS for PTP:
- No new draft updates since the last IETF meeting.
- Authors are discussing points raised at the last IETF, including replay problems and TLVs.
- Implementation work is ongoing, with key management almost complete, but further progress requires clarification on TLV issues.
- The 1588 Security Subcommittee is the forum for some of these discussions.
Greece Mechanism Discussion (General):
- A proposal was made to introduce "grease" mechanisms (e.g., random records, unknown crypto suites) into NTPv5 and NTS, inspired by positive experiences in TLS 1.3 and QUIC.
- The experience from TLS 1.3, where lack of grease caused middlebox issues, was cited as a strong argument.
- A sense of those present indicated strong support for exploring grease in NTPv5 and NTS to improve protocol evolution and resilience against rigid middleboxes.

Decisions and Action Items

NTP Requirements Draft:
- ACTION: James to assist with moving the draft-ietf-ntp-requirements document to the NTP Working Group GitHub organization.
- ACTION: James, David, and the chairs to conduct one more round of comment resolution, aiming to address remaining minor issues for publication.
NTPv5 and Roughtime Hackathon:
- DECISION: Plan a hackathon for NTPv5 and Roughtime implementations at IETF 118 in Dublin (November 2023).
- ACTION: Chairs and respective document authors to coordinate the hackathon planning and encourage participation.
Greece Mechanism:
- ACTION: David to prepare initial suggestions for integrating "grease" mechanisms into NTPv5 and NTS documents in the coming weeks.

Next Steps

Document Progression: Continue to monitor the progression of draft-ietf-ntp-update-registries, draft-ietf-ntp-enterprise-profile, draft-ietf-ntp-ntp-over-ptp, and draft-ietf-ntp-interleave-modes towards publication.
NTPv5 Specification: Merav to proceed with moving the unsynchronized status field and continue addressing the reference clock ID issue. Implementers are encouraged to provide reviews and feedback.
Roughtime: Submit the pending text revision Pull Request. Marcus and Watson to incorporate comments and prepare a next revision.
NTS Implementation Issue: Continue the discussion on the mailing list to gather broader input and potential solutions.
NTS for PTP: Martin and Rina to continue discussions on replay/TLVs, aiming for a significant draft update around February 2024. Continue implementation efforts.
Coordination: Keep an eye out for scheduling of the informal joint meeting between the IETF NTP WG and the IEEE 1588 community.
Interim Meeting: A quick virtual interim meeting might be scheduled prior to the November face-to-face IETF 118 meeting depending on progress.