nanog mailing list archives
Re: NTP Sync Issue Across Tata (Europe)
From: John Gilmore <gnu () toad com>
Date: Sat, 12 Aug 2023 19:14:06 -0700
Forrest Christian (List Account) <lists () packetflux com> wrote:
At some point, using publicly available NTP sources is redundant unless one wants to mitigate away the risks behind failure of the GPS system itself.
On Fri, Aug 11, 2023, 3:33 AM Masataka Ohta wrote:
Your assumption that public NTP servers were not GPS-derived NTP servers is just wrong.
Subsequent conversation has shown that you are both right here. Yes, many public NTP servers ARE using GPS-derived time. Yes, some public NTP servers ARE NOT using GPS-derived time. Up to this point, popular public NTP pools have not made these distinctions readily configurable, though. For sites that need to run even during a war, or a similar situation that is likely to disrupt or distort GPS, they might like to have access to NTP servers that are completely independent from GPS. At one point I proposed that some big NTP server pools be segregated by names, to distinguish between GPS-derived time and national-standard derived time. For example, two domain names could be e.g.: fromnist.pool.tick.tock fromgps.pool.tick.tock If you wanted particular redundancy, say because you have a local GPS clock and you want a non-GPS check on that, you'd use fromnist.pool.tick.tock (or fromnict.pool.tick.tock for the Japanese timebase, etc). (If you were agnostic about where your times comes from, you would just use a generic domain name like vendorname.pool.tick.tock.) An automated tool could periodically trace that the stratum 0 source currently being used by each node in each of the pools is actually the same as advertised in its domain name. Alerting any difference to the relevant system administrators would allow those clocks to continue running with a backup timebase, while making it more likely that some human would work to restore their access to the correct stratum 0 source. So far this is just an idea. John PS: When we say "GPS", do we really mean any GNSS (global navigation satellite system)? There are now four such systems that have global coverage, plus regionals. While they attempt to coordinate their time-bases and reference-frames, they are using different hardware and systems, and are under different administration, so there are some differences in the clock values returned by each GNSS. These differences and discontinuties have ranged up to 100ns in normal operation, and higher amounts in the past. See: Nicolini, Luca; Caporali, Alessandro (9 January 2018). "Investigation on Reference Frames and Time Systems in Multi-GNSS". Remote Sensing. 10 (2): 80. doi:10.3390/rs10010080. https://www.mdpi.com/2072-4292/10/1/80
Current thread:
- Re: NTP Sync Issue Across Tata (Europe), (continued)
- Re: NTP Sync Issue Across Tata (Europe) Jay R. Ashworth (Aug 13)
- Re: NTP Sync Issue Across Tata (Europe) Forrest Christian (List Account) (Aug 13)
- Re: NTP Sync Issue Across Tata (Europe) Jay R. Ashworth (Aug 13)
- Re: NTP Sync Issue Across Tata (Europe) Forrest Christian (List Account) (Aug 09)
- Re: NTP Sync Issue Across Tata (Europe) Seth Mattinen via NANOG (Aug 09)
- Re: NTP Sync Issue Across Tata (Europe) Mel Beckman (Aug 09)
- Re: NTP Sync Issue Across Tata (Europe) Forrest Christian (List Account) (Aug 09)
- Re: NTP Sync Issue Across Tata (Europe) Masataka Ohta (Aug 11)
- Re: NTP Sync Issue Across Tata (Europe) Forrest Christian (List Account) (Aug 11)
- Re: NTP Sync Issue Across Tata (Europe) Masataka Ohta (Aug 11)
- Re: NTP Sync Issue Across Tata (Europe) John Gilmore (Aug 12)
- Re: NTP Sync Issue Across Tata (Europe) Masataka Ohta (Aug 13)
- Re: NTP Sync Issue Across Tata (Europe) Forrest Christian (List Account) (Aug 14)
- Re: NTP Sync Issue Across Tata (Europe) Mel Beckman (Aug 14)
- Re: NTP Sync Issue Across Tata (Europe) Forrest Christian (List Account) (Aug 14)
- Re: NTP Sync Issue Across Tata (Europe) sronan (Aug 16)
- Re: NTP Sync Issue Across Tata (Europe) James R Cutler (Aug 14)
- Re: NTP Sync Issue Across Tata (Europe) Mike Hammett (Aug 14)
- Re: NTP Sync Issue Across Tata (Europe) Mike Hammett (Aug 13)
- Re: NTP Sync Issue Across Tata (Europe) Masataka Ohta (Aug 14)
- Re: NTP Sync Issue Across Tata (Europe) Masataka Ohta (Aug 09)