ATM (was Re: too many routes)
avg at pluris.com
Fri Sep 12 03:05:13 UTC 1997
Richard Irving wrote:
> Light can travel around the world 8 times in 1 second. This means it
> can travel
> once around the world (full trip) in ~ 120 ms. Milliseconds, not
You've got faster light than anybody else. The speed of light
is about 300000 km/s _in vacuum_; that gives 134 ms arond the
> So, why does one trip across North america take 70ms...
a) light is slower in dense media
b) fibers are not laid out in straight lines (in fact, i saw
a circuit going from Seattle to Vancouver via Fort Worth :)
70 ms RTT = 35 ms one way. Given that U.S. is about 50 deg. wide,
it is abput 0.7ms/degree; or 250 ms around the world.
Less than 2 times slower than light in vacuum.
> Hint, it is not the speed of light. Time is incurred encoding,
> decoding, and routing.
Hint: have a look at a telco's fiber map before spreading
More information about the NANOG