NTp sources that work in a datacenter (was Re: Is latency equivalent

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1

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

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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.

3

(replying to Peter on NTP have always struck me as a bad idea.... :wink: )

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 -