[e2e] Re: crippled Internet
cannara at attglobal.net
Wed Apr 25 20:36:38 PDT 2001
There are ITU specs for jitter and delay in voice that have been used for
years in standard telco system design. I should think these would be easily
accessible, but I only have a couple of graphs on paper. The basic idea is
that 50mS or so of frequent variation in sample arrival time is hard for
listeners, and 100mS roundtrip delay becomes annoying in conversations.
Randy Bush wrote:
> >> please explain how we might judge whether the these are sufficient for say
> >> voip.
> > without knowing the specifics of the test scenario
> RFC2680. and note that we have distributions of one-way delay here, not
> some standard deviation of ping times. as to how they were measured, see
> <http://www.ripe.net/ripencc/mem-services/ttm/index.html>. i can not tell
> you between what host or provider pairs the particular measurements were
> taken, as that would extend the consent of the measured beyond the present
> limits. and i don't think it really matters.
> > it's hard to say much from them.
> if true, then this whole discussion is pretty pointless.
> > But they appear to suggest that some packets experienced 500 ms of delay
> > (however that was measured) and some experienced virtually none.
> zero packets experienced none. the speed of light is still in force despite
> many attempts to overturn.
> considering that *extremely* few experienced delay far from the mode, what
> can we say about what is reasonable for voip? can we quantify it in some
> way we can actually measure to see if we're doing well? i.e. real numbers
> please, not that someone in the press or on henning's corridor whines.
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