[130415] in North American Network Operators' Group
Re: A New TransAtlantic Cable System
daemon@ATHENA.MIT.EDU (kris foster)
Sat Oct 2 14:28:46 2010
From: kris foster <kris.foster@gmail.com>
In-Reply-To: <AANLkTi=fiTnQSQVqT3mNUN6RQTW818bRVW8L9+z5GcY0@mail.gmail.com>
Date: Sat, 2 Oct 2010 11:28:02 -0700
To: Jon Meek <meekjt@gmail.com>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
http://www.gcmap.com/mapui?P=lga-lhr
--
kris
On Oct 2, 2010, at 7:31 AM, Jon Meek wrote:
> One of the ways that I have tormented WAN vendors over the years is
> with a plot of RTT vs. great circle distance between the end points of
> a circuit. Most RTTs usually sit at some constant offset above that
> Physics limit straight line. Circuits taking a less than ideal have
> their RTT far above the Physics limit line and we have used that
> information to get routes fixed.
>
> Using my great circle program that accounts for the non-spherical
> Earth for locations we have West of London and North of NYC, assuming
> a 1.5 index of refraction I get:
>
> One way distance: 5520.6 km Round Trip Delay: 55.2 ms
>
> So Heath's estimate is right on, although depending on where he got
> the distance maybe it does account for the shape of the Earth.
>
> Jon
>
> On Sat, Oct 2, 2010 at 6:17 AM, Heath Jones <hj1980@gmail.com> wrote:
>> On 2 October 2010 10:52, Rod Beck <Rod.Beck@hiberniaatlantic.com> wrote:
>>> Is that a straight line calculation or did you take into account that a
>>> straight line is not the shortest path on a curved surface?
>>
>> Well that is pretty obvious to most, but no - I didn't go to the
>> effort of factoring in curvature of the earth - especially given that
>> 1.5 is very rough figure anyway for RI of glass. If anything, my
>> comment was compliment to your network being close to minimum possible
>> latency!
>>
>>
>
