DMM

IETF 125 - Distributed Mobility Management (DMM) Working Group Minutes

Summary

The DMM Working Group met at IETF 125 to discuss the status of active documents, technical updates to mobile traffic steering, a new YANG model for attachment circuits, and emerging research on mobility management for Low Earth Orbit (LEO) satellite networks. Key highlights included the successful commercial deployment of SRv6 Mobile User Plane (MUP) in Japan and the transition of Area Directors (ADs).

Key Discussion Points

Working Group Status

Presenter: Sri Gundavelli Slides: Working Group Status

Mobility Aware Transport Network Slicing for 5G: The draft is currently under AD review and is expected to be sent to the IESG soon.
SRv6 Mobile User Plane: Satoru Matsushima reported that SRv6 MUP (related to draft-ietf-dmm-mup-architecture) has been successfully deployed commercially in SoftBank's network. Text updates for draft-ietf-dmm-srv6mob-arch are planned for the next meeting.
Mobile Traffic Steering: draft-ietf-dmm-mts is active with new revisions published.

Mobile Traffic Steering (MTS)

Presenter: Marco Liebsch Draft: draft-ietf-dmm-mts Slides: Mobile Traffic Steering

Updates: Version 01 of the working group draft includes clarifications on node ephemerality for Non-Terrestrial Networks (NTN) and editorial improvements.
Architecture: The focus is on the Control Plane Mobile Traffic Steering (CMTS) API between the mobile communication system and the transport network.
Information Model: The authors proposed an Entity-Relationship Diagram (ERD) to replace basic tables in the appendix to better handle cardinalities and relationships between Traffic Descriptors, Path Identifiers, and User Plane Anchors (UPA).
Discussion: John Kaippallimalil inquired about flow prioritization and IP address stability during anchor reselection. Marco Liebsch clarified that IP addresses remain transparent to the steering process and the mobile system notifies the transport network of anchor changes.

A YANG Data Model for Attachment Circuit as a Service (ACaaS) with UDP Tunnel Support

Presenter: John Kaippallimalil Slides: A YANG Data Model for Attachment Circuit as a Service with UDP Tunnel Support

Context: This draft was split from the Transport Network Aware (TNA) mobility work following a request from the Operations AD. It extends existing Layer 2 attachment circuit models to support Layer 3 UDP tunnels.
Status: The model has been validated. The authors are addressing minor comments from the adoption call.
Discussion: Lionel Morand and Satoru Matsushima noted that the split was primarily administrative and the content is mature.

Mobility Management for Inter-SNO Sharing in LEO Satellite Networks

Presenter: Yunan Hou Slides: Mobility Management for Inter-SNO Sharing in LEO Satellite Networks

Problem: High LEO satellite velocity leads to frequent inter-Satellite Network Operator (SNO) handovers (20-80 per hour) when infrastructure is shared.
Proposed Solution: A framework featuring shared LEO access, independent SNO cores, and proactive switching based on predictable satellite trajectories.
Discussion: John Kaippallimalil raised concerns regarding the assumption of shared "Points of Presence" (PoP) to the internet. Lionel Morand suggested that if the access network is shared, it should ideally appear as a single SNO to the user to avoid IP-layer handovers. Sri Gundavelli recommended the authors focus first on a formal problem statement.

Decisions and Action Items

Document Adoption: The chairs will formally confirm the adoption of the ACaaS YANG model draft on the mailing list.
AD Transition: Eric Vyncke is stepping down as the responsible Area Director. Tommy Jensen will take over the role starting Wednesday of the IETF 125 week.
IESG Tracking: Authors of the Mobility Aware Transport Network Slicing draft (John Kaippallimalil et al.) will track and address forthcoming IESG comments.

Next Steps

MTS Draft: Marco Liebsch to schedule interim calls to refine the Information Model for draft-ietf-dmm-mts.
Satellite Mobility: Yunan Hou to consider developing a problem statement draft based on feedback regarding architectural assumptions and inter-operator roaming.
SRv6 Mob Arch: Authors to refresh draft-ietf-dmm-srv6mob-arch prior to IETF 126.

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