Re: [rtcweb] Network times . was SDP Security Descriptions (RFC 4568) and RTCWeb

[Justin Uberti <[e-mail]>]

Worldwide, a significant fraction of 2G and 3G mobile users experience RTT
> 1500 ms. I am not suggesting that we design for these extreme cases,
however.


On Thu, May 2, 2013 at 7:15 PM, Cullen Jennings <[e-mail]> wrote:

>
> On May 1, 2013, at 12:30 PM, Randell Jesup <[e-mail]> wrote:
>
> > On 5/1/2013 9:01 AM, Justin Uberti wrote:
> >> This doesn't match what we are seeing. I pulled some Chrome stats on
> average RTT seen across various network connections; on 3G, close to half
> of users had RTTs > 250 ms. 4G is somewhat better. 2G is considerably worse.
> >>
> >> India continues to be especially bad, partially because of the above,
> partially because of use of satellite links, which due to physics incur 500
> ms RTTs.
> >
> > Those are all RTT measurements, so One Way Delay's of roughly half of
> that?  speed-of-light for a one-way satellite link would be around 280ms in
> theory - and of course that's just for that one physical link.
>
> By one way here, you mean up to the satellite link, then back down to the
> ground again which the satellite people often don't call one way but I
> agree it is the network latency measurement from browser to browser we are
> looking for. You are of course correct that, for geosync satellites that
> are at somewhere around 42,000 km up, we get around 240 to 280 ms depending
> on your relative location to the satellite. But, keep in mind the preferred
> satellites for this type of stuff are globalstar at 1400 km or iridium at
> less than 800 km which have way less latency than geosync.
>
> I'm still looking for the elusive 1500 ms.
>
>
> >
> > --
> > Randell Jesup
> > [e-mail]
> >
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