mailing list archives
Re: Non-GPS derived timing sources (was Re: NTp sources that work in a datacenter)
From: Sean Donelan <sean () donelan com>
Date: Sun, 1 Jun 2003 23:57:21 -0400 (EDT)
On Sun, 1 Jun 2003, Marshall Eubanks wrote:
Every major time service and most national standards labs maintain a
set of clocks of comparable accuracy - US, UK, France, Germany, Russia,
Japan, Australia, etc., so there is no shortage of timing info to
compare it with.
Actually my question wasn't so much about other national standards labs,
but that almost every major Internet backbone worldwide seems to trace
their time source to GPS. Maybe not that surprising for US/North American
providers, but even non-american backbones seem to use GPS.
To be clear, I'm not talking about individuals syncing things to lots of
different clocks. Clock.ORG has lots of clock sources around the world.
I'm talking about what network providers use.
It was just one of those midnight projects a month or so ago, when I
noticed my carefully balanced selection of tickers had slowly over the
last few years all changed from other time sources to GPS. Probably
not critical, but national standards labs have accidentily flipped
the wrong switch in the past and done strange things to their time
broadcasts. Yes, lots of people noticed, and it was fixed quickly. NTP
has all this great logic for sanity checking time sources, but if they
all come from the same origin, what happens?