Re: NTP Sync Issue Across Tata (Europe)

[Martin Hannigan <hannigan () gmail com>]

Same here. Latency and the algo work together. Time outs or un-reachable peers are network issues.

Paging Randy Bush.

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________________________________
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