Re: [Ntp] Antw: Re: Antw: Re: Antw: [EXT] Re: New Version Notification for draft‑gruessing‑ntp‑ntpv5‑requirements‑03.txt

[Doug Arnold <[e-mail]>]

My understanding is that Google builds all of its own timing infrastructure, so they can start with smearing as a part of their architecture.

Now everyone wants to copy the Google Spanner approach to distributed data bases, but with timing from vendors and open source projects.  I wish them luck.

On 10/22/21, 8:19 AM, "Martin Burnicki" <[e-mail]> wrote:
Danny Mayer wrote:
> On 10/22/21 6:00 AM, Martin Burnicki wrote:
>> As I've tried to point out earlier, in any case it's the task of an
>> administrator to ensure a proper configuration:
>>
>> - If there are smearing and not-smearing servers, he has to configure
>> which clients should query the time from which servers.
>>
>> - If the clients should do the smearing, he had to configure each
>> individual client whether to smear, or not.
>>
>> - If a smearing server would only reply to authenticated requests, he
>> had to configure on each client which server(s) to use, and which
>> keys, and it wouldn't even be possible to hide the leap second from
>> dumb clients.
>>
> You also need to worry about the cascading effects of a server accepting
> smeared time turning around a sending out smeared timestamps in response
> to requests from downstream clients. Smearing cannot be considered in
> isolation.

Correct. Cascading servers, mixing smearing and non-smearing time
sources, providing smearing clients with a leap second file, etc. are
another stage of potential problems an admin has to keep in mind in all
of the cases I mentioned.

As I said, smearing is a hack, and I just wanted to point out that it's
not easier to let the clients do the smearing, as some folks here seem
to assume.

In fact, one of the original reasons why Google introduces server-side
smearing was that the only had to configure this on a few servers, and
the configuration of a huge number of clients that were anyway sync'ing
to those servers didn't need to be touched.

Martin
--
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