Hi Ian, Another author of DTP here. Thanks for your comment. Glad to hear that the deadline feature is useful inside Chromium. Can you talk a little bit more about those use cases?
You are right that a simple deadline-awareness feature does not require new frames. We add new frames to build a feedback loop of the deadline delivery. The BLOCK_INFO frame which contains the start time stamp is sent from sender to receiver. The receiver calculates the difference of the expected deadline and the actual block completion time and sent it back to the sender. Sender then uses it to calibrate its estimation of delivery time. The sender can infer it from the ACK but it is affected by the ACK policy such as ACK frequency. We will update the draft to reflect these design considerations. Best, Hang From: QUIC <[email protected]> On Behalf Of Ian Swett Sent: Monday, November 21, 2022 7:17 PM To: Chuan Ma <[email protected]> Cc: [email protected]; Christian Huitema <[email protected]>; [email protected]; [email protected] Subject: Re: Add deadline awareness to QUIC 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 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/ and implemented a > protocol based on QUIC called DTP (Deadline-aware Transport Protocol) in > 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). 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 >
