Re: [MMUSIC] Congestion controll

Emil Ivov <emcho@jitsi.org> Mon, 10 June 2013 18:12 UTC

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From: Emil Ivov <emcho@jitsi.org>
Date: Mon, 10 Jun 2013 20:12:02 +0200
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To: Martin Thomson <martin.thomson@gmail.com>
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Cc: Flemming Andreasen <fandreas@cisco.com>, Ari Keranen <ari.keranen@ericsson.com>, "mmusic@ietf.org" <mmusic@ietf.org>, Cullen Jennings <fluffy@iii.ca>
Subject: Re: [MMUSIC] Congestion controll
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On Mon, Jun 10, 2013 at 7:19 PM, Martin Thomson
<martin.thomson@gmail.com> wrote:
> On 10 June 2013 10:10, Emil Ivov <emcho@jitsi.org> wrote:
>>> I think that this is the part that is getting confused.  This is not a
>>> complaint against plan A or B.
>>
>> It is indeed a problem with both of them and it is also mentioned in the No
>> Plan draft.
>
> Well then you've assumed something about Plan A/B that is incorrect.

I am not following. Could you please point me to the specific
assumption that you have in mind?

> Neither plan constrains usage in a way that would prevent senders from
> responding to congestion signals. The fine-grained control that you
> report as being problematic doesn't prevent senders from sending fewer
> bits.

No, not explicitly at least. However, the more senders respond to
congestion signals the more they end up with inconsistencies between
what's been requested from the remote SDP, what the local application
would like to happen and what is actually happening. Such situations
would be much harder to control when all you've got is the remote SDP.

> Is it possible that you have assumed that the existence of an m-line
> or a=ssrc implies that the sender is obligated to send?

Nope.

Emil

> It doesn't.
>
> The only possible problem is the use of a=imageattr in the examples of
> Plan B, which might (might) overconstrain a sender, but Plan B doesn't
> mandate anything regarding that in text.  Assuming anything there
> would be a real stretch.