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Re: [rmcat] Priority and rtcweb

Michael Welzl <michawe@ifi.uio.no> Tue, 14 November 2017 03:01 UTC

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From: Michael Welzl <michawe@ifi.uio.no>
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Cc: "rmcat@ietf.org" <rmcat@ietf.org>, Zaheduzzaman Sarker <zaheduzzaman.sarker@ericsson.com>, Colin Perkins <csp@csperkins.org>, "W3C@CSIO" <webrtc@callstats.io>
To: Varun Singh <varun@callstats.io>
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Subject: Re: [rmcat] Priority and rtcweb
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> On Nov 14, 2017, at 4:51 AM, Varun Singh <varun@callstats.io> wrote:
> 
> Hi Michael,
> 
> On Mon, Nov 13, 2017 at 10:44 AM, Michael Welzl <michawe@ifi.uio.no <mailto:michawe@ifi.uio.no>> wrote:
> Can I hijack this thread to talk about priority?
> 
> 
> Priority is already defined in the API document to the following levels: high, medium, low, very-low.
> These labels map to the text in the transport document
> 
>         Thus, when congestion occurs, a "high" priority flow will have the
>         ability to send 8 times as much data as a "very-low" priority flow if
>         both have data to send. This prioritization is independent of the
>         media type. The details of which packet to send first are
>         implementation defined.

I know!   The coupled-cc text matches these as well.


> WEBRTC API: https://rawgit.com/w3c/webrtc-pc/master/webrtc.html#dom-rtcprioritytype <https://rawgit.com/w3c/webrtc-pc/master/webrtc.html#dom-rtcprioritytype>
> 
>  
> There was a thread about priority in rtcweb - someone asking for a float… coupled-cc can easily support a float, but Harald’s transport draft doesn’t support it. Opinions went back and forth for a bit...
> I think we should get more WebRTC deployment and not more debate on small details that delays the work, so I don’t want to be a troublemaker and didn’t interfere with this discussion.
> But, what is the view of people in rmcat about this?
> 
> 
> While the API does not provide a float value, nonetheless, doesn't the WebRTC stack or framework under the JS API have all the information to convert the set labels in to a float values after the flows are assigned values? 

Sure, but the point of that discussion was that the definition of these values (high, very-low, etc etc) is too rigid.
We could easily offer a much less rigid priority value - this is no problem at all for coupled-cc (or a scheduler, for that matter).

It is my understanding that the choices of high, very-low etc. were made for simplicity, to just decide on *something* and move forward. I respect that - but I also found it disappointing to see someone complaining about this not supporting more flexible value choices when technically, we can easily do so…

Cheers,
Michael

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