Same here. Latency and the algo work together. Time outs or un-reachable peers are network issues. Paging Randy Bush. Get Outlook for iOS<https://aka.ms/o0ukef> ________________________________ From: NANOG <nanog-bounces+hannigan=gmail.com@nanog.org> on behalf of John Gilmore <gnu@toad.com> Sent: Tuesday, August 8, 2023 17:01 To: Mel Beckman <mel@beckman.org> Cc: nanog@nanog.org <nanog@nanog.org> Subject: Re: NTP Sync Issue Across Tata (Europe)
I was also speaking specifically about installing GPS antennas in viable places, not using a facility-provided GPS or NTP service.
Am I confused? Getting the time over a multi-gigabit Internet from a national time standard agency such as NIST (or your local country's equivalent) should produce far better accuracy and stability than relying on locally received GPS signals. GPS uses very weak radio signals which are regularly spoofed by all sorts of bad actors: https://www.gps.gov/spectrum/jamming/ for all sorts of reasons (like misleading drone navigation): https://en.wikipedia.org/wiki/Iran%E2%80%93U.S._RQ-170_incident Depending on satnav systems creates a large single point of failure for worldwide civilian infrastructure. Jamming GPS with subtly fake time data near big data centers seems like an easy move that would cause all sorts of distributed algorithms to start failing in unusual ways. And in a more serious wartime attack, many or most GPS satellites themselves would be destroyed or disabled. Yet digital radio modulations like FT8 or DMR rely on tight time synchronization among different transmitters. So do many modern cellphone modulations -- not to mention distributed database sync algorithms. Depending on any of these for emergency communications when their time comes from GPS, is a recipe for having no communications during wars or cyber-wars in which GPS satellites are attacked or jammed. See a longer explanation here: https://www.ardc.net/apply/grants/2020-grants/grant-ntpsec/ I suspect that even today, if you rely on civilian GPS time near the US White House, Pentagon, or other military targets like bases, you will discover "anomalies" in the local radio GPS data, compared to what you get from an authenticated time standard over NTP. How reliable is civilian GPS time in Ukraine these days? John