Mikael Abrahamsson <swmike@xxxxxxxxx> wrote: > On Mon, 24 Oct 2011, John Leslie wrote: > >> 150 milliseconds is a real challenge to accomplish worldwide, though >> it's quite achievable within one continent. I expect IETF folks could >> learn to work with 250 milliseconds. > > Are these numbers RTT or one-way? I'm embarrassed to admit I don't know which Brian Rosen meant: perhaps he'll elaborate. He may well have meant one-way delay plus codec delay plus application delay. > According to figures I've seen in other contexts, most people are fine > with 400ms RTT (this is a quite common delay just talking mobile > phone-to-phone even in the same city), I'm pretty sure what I've observed mobile-to-mobile exceeds Brian's criteria... > but people really start to notice around 500-700ms RTT. 1 second RTT > is really noticable, but still workable with some practice. _I_ certainly notice before 500 msec RTT-plus-codec. I don't think I agree that 1 second RTT-plus-codec is workable in groups where any of a half-dozen folks might speak at any time. > It's hard to have a heated argument over more than 400-500 ms RTT > though, Exactly! > so it depends on what kind of discussions are to be had :P It wouldn't be IETF without an occasional heated-discussion! > Ground/sea based fiber optical cable networks rarely give more than > 500ms RTT, so anyone fairly well connected to the worldwide Internet > via ground based infrastructure should be able to participate with > less than 1s RTT including encoding delays etc, There's no reason why ground/sea based fibre needs to exceed about 200 msec RTT; but buffer-bloat does cause this sometimes. In practice, business-level Internet is likely to add 100 msec to this, and cable Internet can add considerably more. :^( > at least if the system is located at the same place or fairly close > to the venue (I'm guessing you mean a single-central-server through which all audio passes.) > (at least so the signal doesn't have to be bounced half way around > the world before it's sent to the final > destination). I don't honestly know how flexible the various vendor systems are in that respect. I would like to believe they are capable of more intelligent switching than that... -- John Leslie <john@xxxxxxx> _______________________________________________ Ietf mailing list Ietf@xxxxxxxx https://www.ietf.org/mailman/listinfo/ietf