Re: [Ntp] Antw: Re: Antw: [EXT] Re: CLOCK_TAI (was NTPv5: big picture)

[Martin Burnicki <[e-mail]>]

Magnus,

Magnus Danielson wrote:
> On 2021-01-11 08:22, Hal Murray wrote:
>> if you are using smearing servers you have to be careful to not use any 
>> non-smearing servers.
>>
>> If you are using real/correct (non-smearing) servers, you have to make sure 
>> you don't use any smearing servers.
> 
> Which is exactly the division of servers and problem to handle them at
> client side, as client operation needs to know which servers too choose
> from. As you create a wider range of server types, all of a sudden you
> create less servers that we can use for any type of operation.

Once more I disagree. If you want smearing at the client side, client
software could be modified to do this right now.

If the client receives a leap second warning from the server, it could
include apply a smear offset when adjusting the system time, and each
client had to be individually configured if and how to smear its own
system time.

The reason for letting the NTP server send smeared time to its clients
is that you *only* have to configure your server(s) accordingly, and
*all* NTP clients get the same, smeared time.

> This is
> why putting this on the server side is unhelpful for the community. If
> we have a common NTP core time and then map that out to whatever format
> the client need, we can have a common set of of servers, serving a wide
> range of clients need together.

Of course you can run into a mess if you use smearing and non-smearing
servers at the same time.

However, admins who have to take care how the clients behave just need
to select a few appropriate servers for their clients instead of having
to check that each client supports smearing at the client side in the
same way. If you have a huge number of different clients, the effort is
probably much higher and more error prone than just having to select a
few servers.


Martin
-- 
Martin Burnicki

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