Subject: [rtcweb] Local prioritization in draft-ietf-rtcweb-transports-11

From: Michael Welzl <[email-masked]>
Date: Fri, 26 Feb 2016 14:10:05 +0100

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