On Mon, Oct 24, 2011 at 9:24 AM, Mikael Abrahamsson <swmike@xxxxxxxxx> wrote:
On Mon, 24 Oct 2011, John Leslie wrote:Are these numbers RTT or one-way? 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), but people really start to notice around 500-700ms RTT. 1 second RTT is really noticable, but still workable with some practice.
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.
It's hard to have a heated argument over more than 400-500 ms RTT though, so it depends on what kind of discussions are to be had :P
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, at least if the system is located at the same place or fairly close to the venue (at least so the signal doesn't have to be bounced half way around the world before it's sent to the final destination).
Long experience with telepresence shows that formal meetings (where you have to wait your turn, there is a moderator or chair, etc) work pretty well with long latencies. It is person to person interactions that start to suffer above about 400 msec (there is research on this from Bell Labs going back I believe into the 1960's). IETF meetings are fairly formal in this sense, so we should be able to tolerate latencies.
Regards
Marshall
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Mikael Abrahamsson email: swmike@xxxxxxxxx
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