[12357] in North American Network Operators' Group
Re: ATM (was Re: too many routes)
daemon@ATHENA.MIT.EDU (Vadim Antonov)
Fri Sep 12 17:14:04 1997
Date: Fri, 12 Sep 1997 14:05:34 -0700
From: Vadim Antonov <avg@pluris.com>
To: rirving@onecall.net
CC: nanog@merit.edu
Richard Irving wrote:
>
> Nathan Stratton wrote:
> >
> > On Thu, 11 Sep 1997, Vadim Antonov wrote:
> >
> > > Quote from Jim Steinhardt's <jsteinha@cisco.com>
> > > personal message:
> > >
> > > >>a) light is slower in dense media
> > >
> > > > The index of refraction of glass is 1.5 vs 1.0 for
> > > > a vacuum. Hence, the speed of light in glass is 2 * 10 **8 m/s.
> > >
> > > That gives 60 ms RTT on 4000 mile line.
> > >
> > > Case closed.
> >
> > Yep, but you also need to add a few ms for electronics in
> > that 4000 mile line.
>
> My original point. (Concerning latency)
You didn't understand, did you? All your calculations were
to disprove Sean's point that the electronics and switching
delays are pretty small (so as to be insignificant) as compared
to the signal propagation delay. Your (wildly inaccurate)
estimate was that more than 50% of time is spent in electronics.
The real figures, however, show that it is at most 5%. I strongly
suspect that if you figure in that fibers aren't going in straight
line, you'll get that down to 0.1-0.5%.
--vadim
