[ntp:questions] Re: What will happen if the only stratum1 (reference clock) is lost.

John Cochran jdc at smof.fiawol.org
Wed Oct 6 14:33:54 UTC 2004

In article <3058f9b4.0410052358.32f8bf94 at posting.google.com>,
Ariel Burbaickij <ariel.burbaickij at gmail.com> wrote:
>Hello dear mailing list participants,
>I have following question:
>Under the condition that the only  announced stratum1 server (server
>with attached
>reference clock) is lost in the network (physically detached from the
>what will happen to all other machines: Will they go in autonomous
>mode (local clock) or will they nevertheless try to get their time
>feed from announced stratum2 servers even if it is known that they do
>not get their feed from stratum1 server?
It depends on how you have your NTP servers configured.

If you do not have a "local" clock set up, then the stratum 2 servers will
eventually encounter a reach of 0 against the missing stratum 1 server and
go unsyncronized and autonomous. This will propagate down to the higher
strata servers until all are autonomous and drifting independently.

However, if you have the following lines in one of your ntp.conf files (for
one of your strata 2 servers)

   fudge stratum 10

Then if the strata 1 server vanishes, the server with the above line will
go autonomous like it would have previously, but will claim to be a syncronized
strata 11 server. Eventually the other NTP servers will also notice the loss of
the strata 1 server and sync to the only available stratum 11 server.

The overall effect is that the network as a whole will drift from the "correct"
time based upon the stability of the server with the fudged clock, but the
entire network will have the "same" incorrect time. This may be good enough if
all you're interested in is the relative timestamps between different machines
in the same network.

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