IETF3GPP

Summary

This coordination meeting focused on reviewing the current state of IETF-3GPP interactions, including liaison statement procedures, IANA assignment tracking, and dependencies between 3GPP specifications and IETF drafts. A key discussion point was the handling of low-latency, high-bandwidth media over wireless networks, particularly for encrypted flows, based on a draft presented by John. The meeting also outlined 3GPP release timelines and planned next steps for ongoing coordination at the upcoming IETF meeting.

Key Discussion Points

Meeting Logistics: Initial challenges with the chat function led to an agreement for participants to unmute and speak directly.
Agenda: The agenda covered overall IETF-3GPP coordination (presented by Lionel) and a specific draft presentation (by John). The overall goal was to identify coordination issues and prepare for the upcoming IETF meeting.
Liaison Statement Procedures:
- Challenges remain with the current liaison tool, particularly regarding attachment handling and 3GPP's expectation of a specific Word document format for incoming liaisons.
- A manual coordination step involving the IETF 3GPP chairs (Charles and Lionel) was suggested to ensure correct processing.
- The need for a written procedure for handling liaisons and a potential update to RFC 3113 were discussed.
IETF-3GPP Coordination Group:
- A new group under the IAB has been created in the IETF data tracker for IETF-3GPP coordination, mirroring the IETF-IEEE model.
- This group facilitates prep calls before IETF meetings to identify discussion topics.
Dependency Tracking Tool: The existing tool for scanning 3GPP documents for IETF draft references is no longer functional. A need to update or replace this tooling was identified.
New Mailing List (Satellite Networking): A new mailing list was created for discussions on satellite technology touch points between IETF and 3GPP, aiming to coordinate without duplicating or conflicting with 3GPP work.
Liaison Statements Received (3GPP to IETF):
- SCTP Vulnerabilities: 3GPP SA3 responded to a liaison from Magnus, acknowledging the work on SCTP vulnerabilities and emphasizing the need for a solution. They encouraged participation from 3GPP member companies in the IETF work.
- YANG Models: Netmod is actively discussing a 3GPP request regarding YANG model mechanisms for "is-invariant" and "system-created" concepts. The aim is to find a solution that fits IETF's YANG approach while meeting 3GPP's needs.
IETF to 3GPP Liaisons: No formal liaisons were sent from IETF to 3GPP recently. It was reiterated that active participation from 3GPP delegates in IETF mailing lists and discussions is crucial for advancing topics requested by 3GPP.
IANA Assignments Tracking:
- 3GPP has decentralized the management of IANA requests and implemented internal tracking mechanisms (reporters review specifications, a specific registry).
- For internal 3GPP interfaces, the use of dynamic ports, as documented in TR 29.941, has reduced the need for new IANA port number assignments from IETF.
IETF Draft Dependencies from 3GPP: Lionel provided an update on several IETF drafts that are normative references in 3GPP specifications:
- In Editor Queue/IESG Review: draft-ietf-quic-vtn-reqs, draft-ietf-ace-oauth-profile (extended TTLs). These are close to RFC publication.
- In Working Group Last Call: draft-ietf-pcp-v6 (update), draft-ietf-quic-multipath. The quic-multipath draft is particularly critical for 3GPP and requires further IETF attention.
- ITU Coordination: A new H.248 Megacode for Freight Express requires Lionel to coordinate with an ITU expert and produce a draft.
- Technical Report (TR) References: IETF drafts referenced in 3GPP Technical Reports (TRs) become normative dependencies only if adopted into 3GPP normative specifications. This provides an early indication of potential future dependencies.
3GPP Release Timelines:
- Release 18: Protocol-level work is completing. IETF work supporting Release 18 needs to be near RFC publication.
- Release 19: Content definition is ongoing, with main topics to be defined by December. IETF input or solutions for Release 19 would ideally be available by March-June 2025.
- Release 20/21: Early discussions are starting, potentially including topics like CBD (Content-Based Distribution), with normative aspects possibly in Release 21. 3GPP is trying to notify IETF in advance of potential dependencies.
Low Latency/High Bandwidth Media in Wireless Networks (John's Presentation):
- Problem Statement: How to handle media requiring low latency and high bandwidth over wireless networks, especially given transient link capacity variations and encrypted media. 3GPP Release 18 addressed this for unencrypted RTP flows using L4S congestion feedback and selective dropping.
- Challenge: Extending this to encrypted media flows, and also considering future media types (avatars, AI-generated content), and broader application beyond 3GPP (e.g., Wi-Fi, cable networks).
- Solution Options Discussed:
  - DSCP: Difficult to adapt due to limited bits and flow-level granularity.
  - Media Header Extension (e.g., UDP header extensions): Seen as a promising approach for conveying application-level information (delay, loss constraints) to the wireless network classifier.
  - Mask: Involves performance overhead due to decryption at the wireless router.
  - Congestion Control Segments: Complementary to header extensions, operating on longer timescales.
  - Quick Relay / GTP-U: Less practical due to key distribution complexities or reluctance of media servers to adopt.
  - Sharing Keys: Breaks end-to-end security.
- Conclusion: There is a need for a common, secure mechanism for encrypted media across various access types and media transports. This is the start of an important architectural discussion.

Decisions and Action Items

Decision: A new IAB group for IETF-3GPP coordination has been established in the IETF data tracker, including a practice of holding pre-IETF meeting coordination calls.
Decision: 3GPP has implemented internal procedures for tracking IANA assignments and utilizing dynamic ports for internal interfaces, reducing new IANA requests to IETF.
Action Item: Charles and Lionel (IETF 3GPP chairs) will be involved in all IETF-to-3GPP liaison statements to ensure proper formatting and successful delivery, particularly due to 3GPP's specific requirements.
Action Item: Consider updating RFC 3113 to incorporate current liaison statement procedures.
Action Item: Investigate options to update or replace the non-functional tool for scanning 3GPP documents for IETF draft references.
Action Item: Magnus to continue informal outreach and encourage 3GPP member company participation in IETF work on SCTP vulnerabilities.
Action Item: Lionel to contact an ITU expert regarding the H.248 Megacode for Freight Express and work on producing a corresponding draft.
Action Item: Charles and Lionel will continue to remind 3GPP delegates about the importance of active IETF participation (mailing lists, draft reviews) for advancing requested work.
Action Item: Charles and Lionel will share identified "big ticket" items for 3GPP Release 19 with the IETF community once defined.
Action Item: The tsvwg chairs will allocate time on their agenda for further discussion of John's draft on low-latency, high-bandwidth media, and related architectural questions, including coordination with relevant side meetings.

Next Steps

IETF-3GPP Coordination Meeting (IETF 118): A coordination meeting is scheduled during the lunch break on Monday at IETF 118 in San Francisco. The agenda will focus on liaison handling procedures, tooling, and communication strategies with 3GPP. Remote participation will be supported.
TSVWG Discussion: Further discussion on draft-ietf-tsvwg-low-latency-media-wireless is planned within the tsvwg, including potential follow-up from related side meetings.
Dependency Monitoring: Continued monitoring and engagement on the IETF drafts identified as dependencies for 3GPP specifications.

Session Date/Time: 12 Jul 2023 15:00

IETF3GPP

Summary

Key Discussion Points

Meeting Logistics: Initial challenges with the chat function led to an agreement for participants to unmute and speak directly.
Agenda: The agenda covered overall IETF-3GPP coordination (presented by Lionel) and a specific draft presentation (by John). The overall goal was to identify coordination issues and prepare for the upcoming IETF meeting.
Liaison Statement Procedures:
- Challenges remain with the current liaison tool, particularly regarding attachment handling and 3GPP's expectation of a specific Word document format for incoming liaisons.
- A manual coordination step involving the IETF 3GPP chairs (Charles and Lionel) was suggested to ensure correct processing.
- The need for a written procedure for handling liaisons and a potential update to RFC 3113 were discussed.
IETF-3GPP Coordination Group:
- A new group under the IAB has been created in the IETF data tracker for IETF-3GPP coordination, mirroring the IETF-IEEE model.
- This group facilitates prep calls before IETF meetings to identify discussion topics.
Dependency Tracking Tool: The existing tool for scanning 3GPP documents for IETF draft references is no longer functional. A need to update or replace this tooling was identified.
New Mailing List (Satellite Networking): A new mailing list was created for discussions on satellite technology touch points between IETF and 3GPP, aiming to coordinate without duplicating or conflicting with 3GPP work.
Liaison Statements Received (3GPP to IETF):
- SCTP Vulnerabilities: 3GPP SA3 responded to a liaison from Magnus, acknowledging the work on SCTP vulnerabilities and emphasizing the need for a solution. They encouraged participation from 3GPP member companies in the IETF work.
- YANG Models: Netmod is actively discussing a 3GPP request regarding YANG model mechanisms for "is-invariant" and "system-created" concepts. The aim is to find a solution that fits IETF's YANG approach while meeting 3GPP's needs.
IETF to 3GPP Liaisons: No formal liaisons were sent from IETF to 3GPP recently. It was reiterated that active participation from 3GPP delegates in IETF mailing lists and discussions is crucial for advancing topics requested by 3GPP.
IANA Assignments Tracking:
- 3GPP has decentralized the management of IANA requests and implemented internal tracking mechanisms (reporters review specifications, a specific registry).
- For internal 3GPP interfaces, the use of dynamic ports, as documented in TR 29.941, has reduced the need for new IANA port number assignments from IETF.
IETF Draft Dependencies from 3GPP: Lionel provided an update on several IETF drafts that are normative references in 3GPP specifications:
- In Editor Queue/IESG Review: draft-ietf-quic-vtn-reqs, draft-ietf-ace-oauth-profile (extended TTLs). These are close to RFC publication.
- In Working Group Last Call: draft-ietf-pcp-v6 (update), draft-ietf-quic-multipath. The quic-multipath draft is particularly critical for 3GPP and requires further IETF attention.
- ITU Coordination: A new H.248 Megacode for Freight Express requires Lionel to coordinate with an ITU expert and produce a draft.
- Technical Report (TR) References: IETF drafts referenced in 3GPP Technical Reports (TRs) become normative dependencies only if adopted into 3GPP normative specifications. This provides an early indication of potential future dependencies.
3GPP Release Timelines:
- Release 18: Protocol-level work is completing. IETF work supporting Release 18 needs to be near RFC publication.
- Release 19: Content definition is ongoing, with main topics to be defined by December. IETF input or solutions for Release 19 would ideally be available by March-June 2025.
- Release 20/21: Early discussions are starting, potentially including topics like CBD (Content-Based Distribution), with normative aspects possibly in Release 21. 3GPP is trying to notify IETF in advance of potential dependencies.
Low Latency/High Bandwidth Media in Wireless Networks (John's Presentation):
- Problem Statement: How to handle media requiring low latency and high bandwidth over wireless networks, especially given transient link capacity variations and encrypted media. 3GPP Release 18 addressed this for unencrypted RTP flows using L4S congestion feedback and selective dropping.
- Challenge: Extending this to encrypted media flows, and also considering future media types (avatars, AI-generated content), and broader application beyond 3GPP (e.g., Wi-Fi, cable networks).
- Solution Options Discussed:
  - DSCP: Difficult to adapt due to limited bits and flow-level granularity.
  - Media Header Extension (e.g., UDP header extensions): Seen as a promising approach for conveying application-level information (delay, loss constraints) to the wireless network classifier.
  - Mask: Involves performance overhead due to decryption at the wireless router.
  - Congestion Control Segments: Complementary to header extensions, operating on longer timescales.
  - Quick Relay / GTP-U: Less practical due to key distribution complexities or reluctance of media servers to adopt.
  - Sharing Keys: Breaks end-to-end security.
- Conclusion: There is a need for a common, secure mechanism for encrypted media across various access types and media transports. This is the start of an important architectural discussion.

Decisions and Action Items

Decision: A new IAB group for IETF-3GPP coordination has been established in the IETF data tracker, including a practice of holding pre-IETF meeting coordination calls.
Decision: 3GPP has implemented internal procedures for tracking IANA assignments and utilizing dynamic ports for internal interfaces, reducing new IANA requests to IETF.
Action Item: Charles and Lionel (IETF 3GPP chairs) will be involved in all IETF-to-3GPP liaison statements to ensure proper formatting and successful delivery, particularly due to 3GPP's specific requirements.
Action Item: Consider updating RFC 3113 to incorporate current liaison statement procedures.
Action Item: Investigate options to update or replace the non-functional tool for scanning 3GPP documents for IETF draft references.
Action Item: Magnus to continue informal outreach and encourage 3GPP member company participation in IETF work on SCTP vulnerabilities.
Action Item: Lionel to contact an ITU expert regarding the H.248 Megacode for Freight Express and work on producing a corresponding draft.
Action Item: Charles and Lionel will continue to remind 3GPP delegates about the importance of active IETF participation (mailing lists, draft reviews) for advancing requested work.
Action Item: Charles and Lionel will share identified "big ticket" items for 3GPP Release 19 with the IETF community once defined.
Action Item: The tsvwg chairs will allocate time on their agenda for further discussion of John's draft on low-latency, high-bandwidth media, and related architectural questions, including coordination with relevant side meetings.

Next Steps

IETF-3GPP Coordination Meeting (IETF 118): A coordination meeting is scheduled during the lunch break on Monday at IETF 118 in San Francisco. The agenda will focus on liaison handling procedures, tooling, and communication strategies with 3GPP. Remote participation will be supported.
TSVWG Discussion: Further discussion on draft-ietf-tsvwg-low-latency-media-wireless is planned within the tsvwg, including potential follow-up from related side meetings.
Dependency Monitoring: Continued monitoring and engagement on the IETF drafts identified as dependencies for 3GPP specifications.