Re: [rtcweb] An input for discussing congestion control (Fwd: New Version Notification for draft-alvestrand-rtcweb-congestion-00.txt)

Randell Jesup <randell-ietf@jesup.org> Wed, 21 September 2011 13:29 UTC

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Subject: Re: [rtcweb] An input for discussing congestion control (Fwd: New Version Notification for draft-alvestrand-rtcweb-congestion-00.txt)
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On 9/21/2011 4:23 AM, Harald Alvestrand wrote:
> I think receiver->sender reporting every RTT (or every packet, which 
> is frequently less frequent) is overkill, but that's a statement with 
> a lot of gut feeling and very few numbers behind it.
>
> One advantage we have in RTCWEB is that we can assume that if audio 
> and video work OK across the network, we're in a good place. We don't 
> have to worry about getting gigabyte file transfers to utilize 90% of 
> the link - even thogh we have to worry about audio and video 
> functioning while those gigabyte transfers are taking place.

Agreed.  Also, in practice the TCP flows we're competing with are rarely 
long-lived
high-bandwidth flows like GB file transfers.  Normally they're flurries 
of short-lived TCP
(which is important to consider since these short-lived flows can 
suddenly cause buffering
without warning).

As for 1 feedback/RTT, I agree.  And if you wanted to use one 
feedback/RTT, I'd put the feedback in
a TCP header extension or design an RTP equivalent that can carry it in 
the reverse-direction
media flow (when available).  But that's a different argument.

-- 
Randell Jesup
randell-ietf@jesup.org