Liaison statement
LS on need for Multi-Path QUIC for ATSSS

1. Overall Description:
3GPP has approved the study item on “Study on Access Traffic Steering, Switch
and Splitting support in the 5G system architecture Phase 2” as part of Release
17.

This study aims to investigate the extension of Rel-16 ATSSS feature enabling
the support of steering, switching and splitting the traffic of a PDU session
supported over multiple accesses (namely 3GPP and Non-3GPP access), including
the following objective:

-       Whether and how to support additional steering methods(s). Proposed
solutions shall be based on IETF protocols or extension of such protocols (i.e.
QUIC/MP-QUIC).

Please see attached document for details on study item objectives and timelines.

The work on the study has not yet started in 3GPP, and there are thus no agreed
conclusions. . The goal is to enable steering, switching and splitting of
traffic (primarily UDP) across multiple accesses, including latency sensitive
and real time traffic. Therefore 3GPP is interested to receive regular feedback
on progress and prioritization on the multipath extensions to QUIC.

2. Actions:
To IETF group:
ACTION:         3GPP SA kindly requests IETF to take the above information into
account when discussing future work in prioritizing the multipath work for QUIC.

3. Date of Next TSG-SA Meetings:
3GPP TSG SA#88  17th – 19th June 2020   Malmö, SWEDEN
3GPP TSG SA#89  16th – 18th September 2020      Funchal (Madeira), Portugal