Re: [AVTCORE] [tsvwg] [rtcweb] WG Last Call on changes: draft-ietf-avtcore-rtp-circuit-breakers-16

Colin Perkins <csp@csperkins.org> Tue, 28 June 2016 21:48 UTC

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From: Colin Perkins <csp@csperkins.org>
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To: John Leslie <john@jlc.net>
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Cc: "rtcweb@ietf.org" <rtcweb@ietf.org>, tsvwg <tsvwg@ietf.org>, Michael Welzl <michawe@ifi.uio.no>, IETF AVTCore WG <avt@ietf.org>
Subject: Re: [AVTCORE] [tsvwg] [rtcweb] WG Last Call on changes: draft-ietf-avtcore-rtp-circuit-breakers-16
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> On 28 Jun 2016, at 01:04, John Leslie <john@jlc.net>; wrote:
> Colin Perkins <csp@csperkins.org>; wrote:
>> On 27 Jun 2016, at 21:52, Michael Welzl <michawe@ifi.uio.no>; wrote:
>> 
>>> Why even bother considering CE-marks as information for a circuit breaker?
>> 
>> Because the alternative is that we only break the circuit once the queue
>> has been driven into overflow, and packets have been lost.
>> We want to avoid that, since it causes latency, and too much latency is
>> very bad for the user experience. 
> 
>   If you want a circuit-breaker to control latency, why aren't you measuring
> latency?

Because the RTP circuit breaker needs to work with unmodified RFC 3550-style RTCP, which doesn’t return RTT samples sufficiently often to allow that, and because we don’t care about the precise latency, we just don’t want to fill a large queue.

-- 
Colin Perkins
https://csperkins.org/