On 2015-02-20 16:58, William Unruh wrote:
On 2015-02-20, Nuno Pereira <[email protected]> wrote:
In our infrastructure we had some ntp clients that don't have access to the
world and so they are configured to use only 2 servers (by the way, the other
have 2 more options). In reality both servers are the same, but with different
IPs.
So you only have one server. Why have two that are the same?
From time to time some clients configured in this way lose their reference for
some short period.
I know how NTP works
(http://www.ntp.org/ntpfaq/NTP-s-algo-real.htm#Q-NTP-ALGO), and so this seems
to be caused by both 2 servers or just 1 of them not have survived.
But both the clients and the servers are physically in the same place, and
even if they aren't in the same IP network, they are in the same LAN with just
a switch or two between them (delay is between 1 and 2 ms).
What is the switch? Smoke signals? Any switch should be a lot lot faster
than 1ms.
And the question is why this does happen in the local network?
Aren't they close enough in order to avoid a split?
Given that, I have changed the configuration, and now they only use 1 server,
but that is not a good solution.
But that is what you have!
Any alternative for the configuration? More servers, most likely virtual
servers?
I dislike the term servers here and prefer sources, as what you need are
3-5 independent sources of time. You can get that by setting up NTP on
some other Internet facing physical servers (Windows, Linux, BSD) whose
CPUs and network I/O are not overloaded, using pool and/or separate,
local, independent sources, and have all your internal clients configured
to sync from all of those internal sources.
You will have to roll patchings across your internal time sources with
delays to ensure that no more than one source is out of sync at any time.
--
Take care. Thanks, Brian Inglis
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