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Re: Anotherj RFP without IETF community input

2011-10-24 08:37:59
On Mon, Oct 24, 2011 at 9:24 AM, Mikael Abrahamsson 
<swmike(_at_)swm(_dot_)pp(_dot_)se>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? 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.

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



--
Mikael Abrahamsson    email: swmike(_at_)swm(_dot_)pp(_dot_)se

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