Re: NTp sources that work in a datacenter (was Re: Is latency equivalent
The receiver do not need to be in the datacenter, there is this thing called "the internet" that you can hook it up to.
in every PoP to do measurements. In that case, the difficulty isn't in measuring one-way latency, it's in synchronizing the time on all the servers. And with fairly cheap GPS and CDMA clocks that is a lot easier/cheaper than it once was.
a robust mesh of strat-2 chimers gives one more resilence and more accuracy than syncing off a single source.
But what GPS clock can you install in a datacenter? AFAIK, they all require roof (or at least window) access in order to install the antenna. (At least, all the GPS based ntp servers I've looked at do). Is that not true of CDMA servers?
some GPS, some PPS, and an atomic source here and there give great diversity and only a few need roof access.
How have others solved this issue? (Short of owning their datacenters.)
Use NTP, run most systems as strat-2
Time2.Stupi.SE and Time4.Stupi.SE are both stratum-1 accessable through the Internet, tracable to UTC-SP (part of TAI) without use of GPS or slaving to CDMA (that slaves to GPS). -P
On Sat, 31 May 2003, Peter Lothberg wrote:
Time2.Stupi.SE and Time4.Stupi.SE are both stratum-1 accessable through the Internet, tracable to UTC-SP (part of TAI) without use of GPS or slaving to CDMA (that slaves to GPS).
I was wondering about everyone using GPS-derived timing sources last week. I looked at 23 different American backbone providers and I think 19 were traceable back to a GPS clock. 3 were traceable back to USNO/NIST NTP servers on the Internet synched to their respective master clocks. And one claimed to be using the ACTS dialup time service. I don't expect GPS to spin out of control soon, but I did wonder how hard it is to find a another reliable clock source of similar quality to GPS to double check GPS. US clocks account for 40% of the input to TAI.
(replying to Peter on NTP have always struck me as a bad idea.... ;-) )
Time2.Stupi.SE and Time4.Stupi.SE are both stratum-1 accessable through the Internet, tracable to UTC-SP (part of TAI) without use of GPS or slaving to CDMA (that slaves to GPS).
...but other free NTP servers are : ntp1.sth.netnod.se ntp2.sth.netnod.se ntp1.gbg.netnod.se ntp2.gbg.netnod.se ntp1.mmo.netnod.se ntp2.mmo.netnod.se Although not as good as STUPIs. - kurtis -
participants (3)
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Kurt Erik Lindqvist -
Peter Lothberg -
Sean Donelan