Hi,
I wasn't aware of this ttl parameter in Chrome. We also studied quite a
bit the addition of deadline-awareness to QUIC a while ago on a ToN
article right there, see Section VIII:
https://dial.uclouvain.be/pr/boreal/object/boreal%3A264704/datastream/PDF_01/view
In short, we added an API to our QUIC implementation to be able to send
"messages" with deadlines attached to it, each message being sent on its
dedicated QUIC stream. Attaching a deadline to a message means that its
stream must be totally delivered within that time, so I guess the ttl
field of Chrome behaves similarly. This allowed us to schedule FEC in a
more clever way, and it might be the case for multipath scheduling too.
For instance with FEC we could spare a lot of bandwidth by protecting
several video frames at once using the deadline and framerate
information (Figure 16 in the article).
That being said, we did not make any specific protocol modification to
use deadlines, we just modified the API to be able to attach deadlines
to streams, like the ttl feature of Chrome. That affected the stream
scheduling and FEC scheduling, but no specific frame was required on our
side so the QUIC specification stayed unmodified.
Looking at MoQ and Webtransport, it could be useful to already provide
deadline information from the WebTransport API and forward this info to
QUIC to be able to do clever streams/fec/multipath/whatever scheduling.
Right now I am working on adding deadline awareness on our new FEC
implem on top of quiche-cf, so do not hesitate to reach out to me if you
have any question or comment.
Cheers,
François
On 21/11/22 12:16, Ian Swett wrote:
This looks like it might be conflating a few features, some of which are
very media specific and some which are more general, such as
prioritization and deadline awareness.
I may have missed it, but I'm not sure I understand why the deadline
awareness requires a new frame. For low latency media, the sender
typically knows what the deadline is, so it has no need to communicate
it to the peer, unless this design has relays in mind. If so, Media
over QUIC is even more the right venue for this.
For example, the Chromium QUIC code has had a ttl feature for a few
years that we've used for various use cases:
https://source.chromium.org/chromium/chromium/src/+/main:net/third_party/quiche/src/quiche/quic/core/quic_stream.cc;l=1384
<https://source.chromium.org/chromium/chromium/src/+/main:net/third_party/quiche/src/quiche/quic/core/quic_stream.cc;l=1384>
Ian
On Tue, Nov 15, 2022 at 11:03 AM Chuan Ma <[email protected]
<mailto:[email protected]>> wrote:
Hello Huitema and Sarikaya, thanks for the reply.
You are correct that some of our designs are similar to MoQ answers.
For example, we both use partial delivery to improve real-time app
delivery. Actually, we sent the draft to the MoQ mailing list and
discussed the detailed design and which layer to place the module.
But our draft focuses on providing general deadline-aware transport
service as a QUIC extension which is out of the scope of MoQ. MoQ
builds on top of QUIC and is explicitly tailored to media delivery.
We would like to hear the opinion of the QUIC community to see the
need for such a *general deadline-aware transport service*.
On Tue, Nov 15, 2022 at 7:12 AM Behcet Sarikaya
<[email protected] <mailto:[email protected]>> wrote:
On Mon, Nov 14, 2022 at 1:05 PM Christian Huitema
<[email protected] <mailto:[email protected]>> wrote:
Hello Chuan Ma,
Your draft aligns very much with some of the options
investigated for
"media over QUIC". Have you considered participating in that
working group?
I agree, this looks very much like media transmission material.
Behcet
-- Christian Huitema
On 11/14/2022 10:20 AM, Chuan Ma wrote:
> Dear all:
>
> I'm Chuan Ma from Tsinghua University. I want to discuss
the deadline
> awareness of the current application and whether we
should add it to the
> QUIC protocol.
>
> Applications may have specific deadline requirements for
data transmission.
> For instance, a video conference application may require
sending the data
> with a deadline of 200ms to enable live interaction. The
application may
> drop the data that misses the deadline, even if the data
has already
> reached the other end. In this case, it is possible to
drop the data after
> the given deadline from the sender to save bandwidth and
decrease queuing
> time. Deadline requirement is also helpful to offer
deadline-aware
> scheduling combined with QUIC stream priority. Such
scheduling methods can
> increase the punctuality of QUIC and allow more data to
arrive on time. It
> is possible to extend QUIC and offer deadline-aware
transport as a service.
>
> Nowadays, deadline-aware data transmission is getting
more and more
> popular. Applications that emphasize real-time
interaction, such as VR/AR,
> gaming, and video conference, are drawing more and more
attention. So
> deadline-aware transport has a lot of use cases. However,
currently, it is
> the application that is responsible for realizing
deadline-aware transport.
> This transport service should be offered by the transport
protocol but not
> be left to the application. It is reasonable to provide
such transport
> service in a new transport protocol, and QUIC is a good base.
>
> We wrote a draft to show this idea in
> https://datatracker.ietf.org/doc/draft-shi-quic-dtp/
<https://datatracker.ietf.org/doc/draft-shi-quic-dtp/> and
implemented a
> protocol based on QUIC called DTP (Deadline-aware
Transport Protocol) in
> https://github.com/STAR-Tsinghua/DTP.git
<https://github.com/STAR-Tsinghua/DTP.git>. We also built a
live stream
> prototype application to compare the performance between
DTP and QUIC (
> https://github.com/STAR-Tsinghua/LiveEvaluationSystem.git
<https://github.com/STAR-Tsinghua/LiveEvaluationSystem.git>). We
found that
> DTP outperformed QUIC in improving data transmission
punctuality and saving
> bandwidth resources. We published the paper in ICNP22 and
built several
> systems like proxy and tunnel based on DTP. It would be a
good idea to give
> this method a try.
>
> We'd like to know what you think about this topic. Please
let us know if
> you have any comments.
>
> Best regards.
>
> Chuan Ma
>
