[ntp:hackers] smearing the leap second
Miroslav Lichvar
mlichvar at redhat.com
Mon Jun 22 08:09:54 UTC 2015
On Sun, Jun 21, 2015 at 11:23:29AM -0400, Brian Utterback wrote:
> What we do want is that if all software in the network were updated and leap
> smear aware, to do the right thing. Then, replacing all of the clients with
> old software, that again it would do the right thing. Then with a mix of
> servers.
> What happens if the clients have a leap second file?
They will probably make two unnecessary steps of the clock as if a
fake leap event was announced.
> Updated
> clients should be able to have a choice of actions. We can do all of this
> with an extension field.
If the clients could be updated to be leap-smear aware, they could be
updated to slew local clock on leap second and no leap smear would be
needed, right?
Leap smearing should be used only as a last resort when serving time
to clients that can't be updated. I hope this won't become a common
thing.
> Using only a refid field doesn't allow for this and
> breaks loop detection for the duration of the smear.
I think the loop detection will break only on the client side. If a
client is synchronized with a leap smearing server, the server will
still see that the client is synchronized to it and will not select
the client for its own synchronization. Is that correct?
--
Miroslav Lichvar
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