Re: [rtcweb] Pictures of congestion control on the Internet - which is more realistic?

[Harald Alvestrand <[e-mail]>]

Would that be a good discussion to have on the rmcat list?

I hear they're close to finishing their requirements and test 
methodology documents.....


On 04/23/2014 06:37 PM, John Leslie wrote:
> Dave Taht <[e-mail]> wrote:
>> I'm not sure if we have a shared definition of "congestion".  Mine is
>> network delays exceeding that of what human factors research notes
>> as "perceptible" with about 20ms as the outer bound.
>     I, OTOH, am quite sure we don't have a shared definition of congestion.
>
>     My preferred definition is rate-of-arrival exceeding rate-of-forwarding.
>
>     But, of course, you don't have to agree with mine -- "shared" merely
> implies _some_ overlap of the sets of definitions we use...
>
>     Dave's, I fear, isn't terribly useful. There is a base latency (in the
> absence of any traffic) which exceeds 20 milliseconds for many paths
> of interest.
>
>     To tell truth, though, most users probably only notice the total delay,
> not the components of it; so I think Dave's metric is useful -- it's just
> not helpful as a measure of "congestion".
>
>     I'd like to follow up a bit on Dave's metric, regardless.
>
>     There's a lot of talk about "buffer-bloat" where I believe we all
> agree the situation would be better with less buffering.
>
>     But can we talk about the other end of that spectrum?
>
>     Surely there is some minimal amount of buffering, for any particular
> traffic, which is needed in order to maintain a reasonable flow rate.
> Most likely, that minimal buffering varies with factors such as RTT. Do
> we even have a shared concept of what those factors are?
>
>     I'd like to see a thread on what is needed as a minimum buffering
> for various kinds of traffic. I suspect that minimum can be fairly small
> except for TCP transport of "large" files...
>
>> http://gettys.wordpress.com/2013/07/10/low-latency-requires-smart-queuing-traditional-aqm-is-not-enough/
>     Excellent as food for thought...
>
> --
> John Leslie <[e-mail]>