Re: [chrony-users] Poor synchronization to local NTP server

[Bill Unruh <unruh@xxxxxxxxxxxxxx>]

On Tue, 16 Mar 2021, Hal Murray wrote:

> [CAUTION: Non-UBC Email]
>
> unruh@xxxxxxxxxxxxxx said:
> > The length of the hop is not the most important thing. You could have a
> > stable long hop, or an unstable short hop, and the long hop would deliver
> > better time.
>
> True, but it could also deliver much worse time if the routing is wildly
> asymmetrical.

In which case chrony will probably downgrade it. Of course if the assymetry is
constant, it will not notice.

If you want good close time, set up a gps -- they cost about $50 and you will
get millisecond accuracy to UTC. If you want to use your local server, not
matter how shitty it is, you can list it as the only server, or list it as
preferred.

> If you don't know the time, it's hard to figure out if the routing is
> symmetric.  I've seen some wildly asymmetric but reasonably stable times from
> NIST to Silicon Valley.

Agreed.
> Maybe we should add geographic coordinates to the NTP protocol so a client can
> sanity check the round trip times.

Uh, the round trip time is easily measureable. It is one of the things the ntp
>

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