Re: [rtcweb] I-D Action: draft-ietf-rtcweb-transports-12.txt

[Michael Welzl <[e-mail]>]

Hi,

On 26 February, I sent an email to rtcweb in which I made some suggestions to this document. I see that these have not been incorporated, and my email has also never been answered (except that I-D.ietf-dart-dscp-rtp was replaced by RFC 7657, but that may not have been due to my email). I can understand that: probably my prior email just drowned in the WebRTC Audio Codec related thread. However I do think that these comments would be good to address, so I'm copying in the email again below.

Cheers,
Michael

----

Hi,

Overall, I like this document a lot - it makes for a very good read!

- but I think it would make sense for section 4.1 to explicitly point to draft-ietf-rmcat-coupled-cc (the next version of which is going to explain how weights much be set to adhere to the priority levels that are described in this section; it's easy, we just didn't have this text in there yet).


To be concrete, I suggest the following two changes:

***
  When an WebRTC implementation has packets to send on multiple streams
  that are congestion-controlled under the same congestion controller,
  the WebRTC implementation SHOULD cause data to be emitted in such a
  way that each stream at each level of priority is being given
  approximately twice the transmission capacity (measured in payload
  bytes) of the level below.
***

should be:

***
  When a WebRTC implementation has packets to send on multiple streams
  that are congestion-controlled under the same congestion controller
  or multiple coupled congestion controllers (e.g. using the mechanism in
  [draft-ietf-rmcat-coupled-cc]),
  the WebRTC implementation SHOULD cause data to be emitted in such a
  way that each stream at each level of priority is being given
  approximately twice the transmission capacity (measured in payload
  bytes) of the level below.
***

(note a fixed nit in there: the second word is "a" instead of "an")


and, perhaps even more importantly, a small change in section 4.2:

***
  More advice on the use of DSCP code points with RTP is given in
  [I-D.ietf-dart-dscp-rtp].
***

should be:

***
  More advice on the use of DSCP code points with RTP as well as coupled
  congestion control is given in [I-D.ietf-dart-dscp-rtp].
***

and in fact I-D.ietf-dart-dscp-rtp should now be RFC 7657.


Cheers,
Michael