Re: 60 ms cross-continent

[Joel Jaeggli <joelja () bogus com>]

Sent from my iPhone

> On Jun 20, 2020, at 9:27 AM, William Herrin <bill () herrin us> wrote:
>
> Howdy,
>
> Why is latency between the east and west coasts so bad? Speed of light
> accounts for about 15ms each direction for a 30ms round trip. Where
> does the other 30ms come from and why haven't we gotten rid of it?
>
> c = 186,282 miles/second

This is c in a vacuum. Light transmission through a medium is slower. In the case of an optical fiber about 31% slower.

My lowest latency transit paths Palo Alto to the ashburn area are around 58ms.  the great circle route for the two dcs 
involved is a distance 2408 miles which gives you a 39.6ms Lower bound.
 
The path isn’t quite a straight as that, but if you  eliminate the 6 routers in the path and count up the oeo regens 
I’m sure you can account most of the extra in the form of distance.

> 2742 miles from Seattle to Washington DC mainly driving I-90
>
> 2742/186282 ~= 0.015 seconds
>
> Thanks,
> Bill Herrin
>
> -- 
> William Herrin
> bill () herrin us
> https://bill.herrin.us/