Hello folks,

The liaison statement seems to suggest that the existing work in 3GPP is either to develop the 5G architecture, or to see how well the current evolution of GTP-U fits the 5G architecture as developed.  It is natural to also expect that the thinking about the 5G architecture has been influenced by the known behavior and features of GTP-U.  The further guidance in the Liaison statement seems to recommend familiarity with 23.50{1,2,3} and 33.501.

I've had a look at some of the documents, and they can be pretty heavy sledding.

draft-bogineni-dmm-optimized-mobile-user-plane-00 is somewhat more compact.  And yet it also focuses a lot of attention on SMF as well as UPF.

Is the IETF expected to make comments only about UPF?

Some previous discussion suggested that whatever UPF would be developed in the IETF, needed to be independent of the control plane.  But presumably 3GPP would like a UPF that offered the control features that are required for SMF as well.  That's a lot of additional features.  It seems to place additional constraints on whether or not an IETF user-plane protocol would be useful for 3GPP.

If the task is only to provide information to 3GPP about what [dmm] is doing, then the task is manageable.  But if we are also required to describe how an IETF user-plane protocol meets or does not meet the requirements in {2,3}3.50{1,2,3} -- that's a difficult task. Moreover, the charging framework has usually been considered outside the jurisdiction of IETF if I remember correctly -- something about anti-trust.

Charlie P.

On 4/11/2018 11:16 AM, Liaison Statement Management Tool wrote:
Title: CP-173160: New Study Item on User Plane Protocol in 5GC
Submission Date: 2018-04-11
URL of the IETF Web page: https://datatracker.ietf.org/liaison/1572/
Please reply by 2018-07-20
From: Satoru Matsushima <satoru.matsush...@g.softbank.co.jp>
To: Sri Gundavelli <sgund...@cisco.com>,Dapeng Liu <maxpass...@gmail.com>
Cc: Dapeng Liu <maxpass...@gmail.com>,Terry Manderson <terry.mander...@icann.org>,Distributed 
Mobility Management Discussion List <dmm@ietf.org>,Sri Gundavelli <sgund...@cisco.com>,Suresh 
Krishnan <sur...@kaloom.com>
Response Contacts: georg.mayer.hua...@gmx.com,3gppliai...@etsi.org
Technical Contacts:
Purpose: For action

Body: 1. Overall Description:
3GPP working group of CT4 (Core and Terminal) would like to inform the IETF 
that CT4 has initiated a study item on user plane protocol in 5GC for 
Release-16 of 5G phase 2 (see CP-173160).

Based on the outcome from the IETF / 3GPP Coordination meeting at IETF#100, 
3GPP CT4 got aware that IETF DMM WG is currently working on a possible 
candidate protocol for the 3GPP 5G user plane protocol.

3GPP CT4 wants to emphasize that currently there is no related evaluation 
ongoing in 3GPP. Nevertheless, a study item was approved for such a study to 
start in the second half of 2018. The study will evaluate between existing 
solutions within 3GPP and other protocols, based on the Release 16 stage 2 
(system architecture) requirements.

3GPP CT4 would like to point IETF DMM to the following specifications on GTP-U. 
The Release 16 stage 2 requirements are not yet known but it is worth looking 
at latest GTP-U spec which will be evaluated through the study as the existing 

•       [1] 3GPP TS 29.281 (V15.1.0): GPRS Tunnelling Protocol User Plane 

Following technical report provides information of how 3GPP considered GTP-U 
apply to user plane of 5G_ph1:

•       [2] 3GPP TR 29.891 (V15.0.0): 5G System – Phase 1; CT4 Aspects

Furthermore, 3GPP would like to give the following general guidance to IETF 
DMM, regarding user plane transport within 3GPP networks. These are technical 
specifications that include also the necessary information to understand which 
architectural, QoS, security-related and high-level requirements GTP-U 
currently complies to within 5G_ph1.

•       [3] 3GPP TS 23.501 (V15.0.0): System Architecture for the 5G System
•       [4] 3GPP TS 23.502 (V15.0.0): Procedures for the 5G System
•       [5] 3GPP TS 23.503 (V15.0.0): Policy and Charging Framework for the 5G 
•       [6] 3GPP TS 33.501 (V0.6.0): Security Architecture (work in progress)

2. Actions:
ACTION:         CT4 respectfully asks IETF DMM to provide any information that 
may be relevant to the above CT4 work by July 2018.

3. Date of Next CT and CT4 Meetings:
CT4#83  26th Feb – 2nd Mar 2018 Montreal, CAN
CT#79   19th – 20th Mar 2018    Chennai, India
CT4#84  16th – 20th April 2018  Kunming, China
CT4#85  21st – 25th May 2018    Osaka, Japan
CT#80   11th – 12th June 2018   La Jolla, USA
CT4#85-bis        9th –13th July 2018   TBD, France
CT4#86  20st – 24th Aug 2018    TBD, USA


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