Subject: [AVT] comments about draft-westerlund-avt-ecn-for-rtp-00

From: Roni Even <[email-masked]>
Date: Sun, 13 Sep 2009 12:04:04 +0300

Hi,

I did a quick review of the draft.

I noticed that you have the support for AVPF as optional and even have in
section 4.2.1 the following text

" RTP/AVPF has not been negotiated, then the RTCP ECN feedback should be
sent in a compound RTCP packet     along with the regular RTCP reports." 

The RTCP ECN message is defined as an RFC 4585  feedback message and as such
can only be sent under AVPF/SAVPF profile and not AVP

I section 4.1.2 you use the ICE option at the session level yet when using
SDP you have the ECN capability as a media level which direction do you
intend to use.

In section 4.3.3 on receiver driven congestion control you can use the flow
control rtcp feedback message (from ccm) to control the video rate. 

Roni Even

  _____

---

From: Magnus Westerlund <[email-masked]>
Date: Thu, 17 Sep 2009 14:06:29 +0200

Hi Roni

Roni Even skrev:
> I noticed that you have the support for AVPF as optional and even have
> in section 4.2.1 the following text
> 
> The RTCP ECN message is defined as an RFC 4585  feedback message and as
> such can only be sent under AVPF/SAVPF profile and not AVP
> 

I think we are going to require (S)AVPF support because of the need for
quick feedback to received CE marked packets. But, we will fix this to
be consistent.

>  
> 
> I section 4.1.2 you use the ICE option at the session level yet when
> using SDP you have the ECN capability as a media level which direction
> do you intend to use.
> 

Hmm, yes another consistency issue that we will look into.

>  
> 
> In section 4.3.3 on receiver driven congestion control you can use the
> flow control rtcp feedback message (from ccm) to control the video rate.
> 
>  

Yes, that is a possibility on how to implement it for unicast. But, we
don't intended to define a complete congestion control system with
response to markings. This draft is focused on providing ECN information
to any adaptation and congestion control mechanism.

cheers

Magnus Westerlund

IETF Transport Area Director
----------------------------------------------------------------------
Multimedia Technologies, Ericsson Research EAB/TVM
----------------------------------------------------------------------
Ericsson AB                | Phone  +46 10 7148287
Färögatan 6                | Mobile +46 73 0949079
SE-164 80 Stockholm, Sweden| mailto: [email-masked]
----------------------------------------------------------------------