Re: New Version Notification for draft-bonaventure-quic-atsss-overview-00.txt

Roland Zink <> Tue, 02 June 2020 22:19 UTC

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Subject: Re: New Version Notification for draft-bonaventure-quic-atsss-overview-00.txt
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From: Roland Zink <>
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Date: Wed, 3 Jun 2020 00:19:08 +0200
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Hi Christian,

When I understood this right for MPTCP then this can be applied 
end-to-end without any ATSSS interaction. The ATSSS proxy is only needed 
when the end servers do not support MPTCP. When there is end-to-end 
MPQUIC then there doesn't seem to be a need for ATSSS as well.

A cellular network often knows something about mobile devices even when 
those devices are not actively using it. A device registers with a 
cellular network and gets an IP address. After that the cellular network 
keeps track of the device location area (only an area, not the exact 
location) even when the device is inactive or connected to WiFi. This is 
done in case some data destinated to the device (IP) arrives in the 
cellular network (PGW/UPF). Then the device is paged in the area and the 
data is delivered after the device becomes active. You can of cause turn 
off cellular if you don't want this.



Am 02.06.2020 um 22:21 schrieb Christian Huitema:
> I think that we should be very clear that the primary goal for QUIC 
> multipath design is end-to-end. For example, a device might very well 
> have connection with 2 cellular networks, each providing their own 
> "advanced" services, and use end-to-end multipath to balance traffic 
> between the two networks.
> We also have to consider multipath privacy. In the ATSSS setup, the 
> device is supposed to establish a connection with the mobile 
> operator's service even in cases when it is only connected to a Wi-Fi 
> network. That means disclosing connectivity and activity to the 
> operator, just in case a backup through cellular might be needed. This 
> is definitely a trade-off that many applications will not want to 
> make. End to end multipath alleviates that concern, because the 
> network operators only learn of the device's activity when the devices 
> actually uses their network.
> -- Christian Huitema
> On 6/2/2020 12:44 PM, Mirja Kuehlewind wrote:
>> Hi Matt,
>> thanks for the feedback. Please note that in ATSSS the UE can decide 
>> to use this multipath service, or not, e.g. if the server provides 
>> multipath support directly (or even do both but not sure how useful 
>> that is). However, using the network supported service can be 
>> beneficial for downlink traffic towards the UE as the network might 
>> have information about network state and potential needs to handover. 
>> This information can be shared with the UE, however, there is no 
>> protocol mechanism to share this information with the server. I 
>> believe we briefly mention this in the draft but I guess this 
>> discussion could definitely be more explicit.
>> Mirja
>> *From: *QUIC <> on behalf of Matt Joras 
>> <>
>> *Date: *Tuesday, 2. June 2020 at 18:36
>> *To: *Spencer Dawkins at IETF <>
>> *Cc: *IETF QUIC WG <>
>> *Subject: *Re: New Version Notification for 
>> draft-bonaventure-quic-atsss-overview-00.txt
>> On Tue, Jun 2, 2020 at 4:39 AM Spencer Dawkins at IETF 
>> < 
>> <>> wrote:
>>     Dear QUIC,
>>     Several of us submitted this draft (which I emphasize has no
>>     special status in IETF, 3GPP, or between IETF and 3GPP).It's
>>     being used as one of the inputs to SA2#139E, which is underway
>>     now (and that also doesn't give it any special status)..
>>     We are, of course, interested in comments, especially if we've
>>     gotten something wrong about QUIC, directions for MP-QUIC, or
>>     apparent gaps.
>>     The QUIC chairs have told us this is an appropriate thing to
>>     discuss on the QUIC mailing list - we did ask.
>> Thank you very much for producing and sharing this document, I agree 
>> it is appropriate for this forum. The diagrams in the document are 
>> especially helpful.
>> That being said, I have a lot of concerns about the feasibility and 
>> usefulness of the schemes in this document. I wonder if this usage of 
>> QUIC is in the spirit of many QUIC deployments, or if it potentially 
>> hinders an application's usage of QUIC. Correct me if I am wrong, but 
>> it seems one of the core tenets of these schemes is that user 
>> applications on mobile devices would have their flows to servers 
>> transparently tunneled over a multipath transport and then 
>> "untunneled" for the final transit to the server. One of the benefits 
>> of QUIC in practice is the ability to potentially bring the transport 
>> implementation "closer" to the application than was traditionally 
>> possible with TCP. One useful signal to applications is the 
>> transport's knowledge of the underlying path state. By transparently 
>> tunneling a QUIC connection over multiple paths this signal is lost. 
>> This has practical implications; the congestion controller used by 
>> the transport cannot proactively act on network switching signals, 
>> and the application cannot proactively adjust its behavior either. As 
>> a trivial example, an ABR streaming video application may detect that 
>> the underlying path has switched and subsequently adjust the 
>> bandwidth. One could imagine partially getting around this problem by 
>> implementing a channel on the UE (i.e. some sort of API) through 
>> which the information about the underlying path state is conveyed to 
>> the QUIC transport which is being tunneled. However, this doesn't 
>> address the loss of information for the server. Additionally, I would 
>> argue that if this UE informational channel exists there is no need 
>> to tunnel QUIC traffic at all -- the QUIC transport being utilized 
>> directly by the application can manage its use of the underlying 
>> network interfaces.
>> Said another way, I think it would be useful to further discuss why 
>> these problems need to be solved in "the network" itself rather than 
>> focusing on making QUIC "natively" capable of optimally navigating 5G 
>> networks.
>>     Best,
>>     Spencer, but not just Spencer
>>     ---------- Forwarded message ---------
>>     From: < <>>
>>     Date: Sat, May 30, 2020 at 8:46 AM
>>     Subject: New Version Notification for
>>     draft-bonaventure-quic-atsss-overview-00.txt
>>     To: SungHoon Seo < <>>, Olivier
>>     Bonaventure <
>>     <>>, Qing An
>>     < <>>,
>>     Markus Amend <
>>     <>>, Andreas Kassler
>>     < <>>, Spencer
>>     Dawkins <
>>     <>>, Mohamed Boucadair
>>     <
>>     <>>, Quentin De Coninck
>>     <
>>     <>>, Mirja Kuehlewind
>>     <
>>     <>>, Olivier Bonaventure
>>     <
>>     <>>, Nicolas Keukeleire
>>     <
>>     <>>, Maxime Piraux
>>     < <>>
>>     A new version of I-D, draft-bonaventure-quic-atsss-overview-00.txt
>>     has been successfully submitted by Olivier Bonaventure and posted
>>     to the
>>     IETF repository.
>>     Name:  draft-bonaventure-quic-atsss-overview
>>     Revision:       00
>>     Title:          3GPP Access Traffic Steering Switching and
>>     Splitting (ATSSS) - Overview for IETF Participants
>>     Document date:  2020-05-30
>>     Group:          Individual Submission
>>     Pages:          29
>>     URL:
>>     Status:
>>     Htmlized:
>>     Htmlized:
>>     Abstract:
>>        This document briefly presents the Access Traffic Steering,
>>        Switching, and Splitting (ATSSS) service being specified
>>     within the
>>        3rd Generation Partnership Project (3GPP). The ATSSS service
>>        provides network support for multihomed devices to select a
>>     path for
>>        transmission (steer), move traffic from one path to another
>>     (switch),
>>        or use multiple paths simultaneously (split).  TS 23.501
>>     specifies an
>>        ATSSS architecture for TCP traffic.
>>        This document presents a snap-shot of the ongoing discussion
>>     in the
>>        3GPP to enable ATSSS for non-TCP traffic, based on the use of
>>     QUIC,
>>        and assesses to what extent IETF specifications can be used to
>>     meet
>>        the ATSSS design goals.  Apparent gaps are also documented.
>>     Please note that it may take a couple of minutes from the time of
>>     submission
>>     until the htmlized version and diff are available at
>> <>.
>>     The IETF Secretariat
>> Matt Joras